The energy source of the sun

Knowledge is power

carbon cycle

How is hydrogen converted to helium in the interior of stars? The first answer to this question was found independently by Hans Bethe in the USA and Karl-Friedrich von Weizsäcker in Germany. In 1938, they discovered the first reaction that converts hydrogen into helium and can provide the energy needed to keep stars alive. The time has come for this: on July 11, 1938, Weizsäcker's manuscript was received by the editors of the journal "Zeitschrift für Physik", and on September 7 of the same year, Bethe's manuscript was received by the editors of the journal "Physical Review". Both papers outlined the discovery of the carbon cycle. Bethe and Critchfield already sent a paper on June 23 containing the most important part of the proton-proton cycle.

This process is quite complex. For its occurrence, it is necessary that, in addition to hydrogen, atoms of other elements, such as carbon, be present in stars. The nuclei of carbon atoms play the role of catalysts. We know well about catalysts from chemistry. Protons attach to carbon nuclei, where helium atoms are formed. Then the carbon nucleus pushes out the helium nuclei formed from protons, and itself remains unchanged as a result of this process.

The figure shows the scheme of this reaction, which has the form of a closed cycle. Consider this reaction starting at the top of the figure. The process begins with the nucleus of a hydrogen atom colliding with a carbon nucleus with a mass number of 12. We designate it as C 12 . Due to the tunneling effect, the proton can overcome the electric repulsion forces of the carbon nucleus and unite with it.

The transformation of hydrogen into helium in the carbon cycle of Bethe reactions in the interior of stars. Red wavy arrows show that the atom emits a quantum of electromagnetic radiation.

The new core already consists of thirteen heavy elementary particles. Due to the positive charge of the proton, the charge of the original carbon nucleus increases. In this case, a nitrogen nucleus with a mass number of 13 arises. It is designated as N 13. This isotope of nitrogen is radioactive and after a while emits two light particles: a positron and a neutrino - an elementary particle, which we will hear about later. Thus, the nitrogen nucleus turns into a carbon nucleus with a mass number of 13, i.e. in C 13 . This nucleus again has the same charge as the carbon nucleus at the beginning of the cycle, but its mass number is already one more. Now we have a nucleus of another isotope of carbon. If another proton collides with this nucleus, then the nitrogen nucleus reappears. However, now it has a mass number of 14, which is N 14 . If a new nitrogen atom collides with another proton, then it goes into O 15, i.e. into an oxygen nucleus with a mass number of 15. This nucleus is also radioactive, it again emits a positron and a neutrino and goes into N 15 - nitrogen with a mass number of 15. We see that the process began with carbon with a mass number of 12 and led to the appearance of nitrogen with a mass number number 15. Thus, the successive addition of protons leads to the appearance of ever heavier nuclei. Let another proton join the nucleus N 15, then two protons and two neutrons fly out of the formed nucleus together, which form the helium nucleus. The heavy nucleus again turns into the original carbon nucleus. The circle is closed.

As a result, four protons combine and form a helium nucleus: hydrogen turns into helium. During this process, energy is released, which is enough for the stars to shine for billions of years.

The heating of stellar matter does not occur at all stages of the chain of reactions we have considered. The stellar matter is heated partly due to electromagnetic radiation quanta, which transfer their energy to the stellar gas, and partly due to positrons, which almost immediately annihilate with the free electrons of the stellar gas. During the annihilation of positrons and electrons, quanta of electromagnetic radiation are also formed. The energy of these quanta is transferred to stellar matter. A small part of the released energy is carried away from the star along with the outgoing neutrinos. We will consider some obscure questions related to neutrinos later.

In 1967, Bethe was awarded the Nobel Prize in Physics for the discovery of the carbon cycle, which he made in 1938 together with von Weizsäcker. In this case, the Nobel Committee apparently forgot that the honor of this discovery does not belong to Beta alone.

We know that cyclic transformation occurs in the presence of catalytic elements: carbon and nitrogen. But in the stellar interior, all three elements do not have to be present. One of them is enough. If at least one reaction of the cycle starts, then the elements-catalysts will appear as a result of subsequent stages of the reactions. Moreover, the course of a cyclic reaction leads to the fact that a well-defined quantitative ratio arises between reluctant isotopes. This quantitative ratio depends on the temperature at which the cycle takes place. Astrophysicists can now, with the help of their spectroscopic methods, carry out a fairly accurate quantitative analysis of cosmic matter. By the ratio between the number of isotopes C 12 , C 13 , N 14 and N 15 it is often possible not only to establish that in the stellar interior there is a transformation of matter according to the carbon cycle, but also at what temperature these reactions occur. However, hydrogen can be converted into helium not only through the carbon cycle. Along with the reactions of the carbon cycle, other, simpler transformations also occur. It is they who make the main contribution (at least on the Sun) to the release of energy. Next, we turn to the consideration of these reactions.

In order to understand the process of the birth and development of ideas about thermonuclear fusion on the Sun, it is necessary to know the history of human ideas about understanding this process. There are many unsolvable theoretical and technological problems in creating a controlled thermonuclear reactor in which the process of controlling thermonuclear fusion takes place. Many scientists, and even more so officials from science, are not familiar with the history of this issue.

It is precisely the ignorance of the history of understanding and representation of thermonuclear fusion on the Sun by humanity that led to the wrong actions of the creators of thermonuclear reactors. This is proved by the sixty-year failure of work on the creation of a controlled thermonuclear reactor, the waste of huge Money many developed countries. The most important and irrefutable proof is that a controlled thermonuclear reactor has not been created for 60 years. Moreover, well-known scientific authorities in the media promise the creation of a controlled thermonuclear reactor (UTNR) in 30...40 years.

2. Occam's Razor

Occam's Razor is a methodological principle named after the English Franciscan friar, nominalist philosopher William. In a simplified form, it reads: "One should not multiply the existing without the need" (or "One should not attract new entities without the most extreme necessity"). This principle forms the basis of methodological reductionism, also called the principle of thrift, or the law of economy. Sometimes the principle is expressed in the words: "That which can be explained in terms of less should not be expressed in terms of more."

IN modern science“Occam's Razor” is usually understood as a more general principle, stating that if there are several logically consistent definitions or explanations of a phenomenon, then the simplest of them should be considered correct.

The content of the principle can be simplified as follows: one does not need to introduce complex laws to explain a phenomenon if this phenomenon can be explained by simple laws. Now this principle is a powerful tool of scientific critical thought. Occam himself formulated this principle as a confirmation of the existence of God. They, in his opinion, can definitely explain everything without introducing anything new.

Reformulated in the language of information theory, the principle of "Occam's Razor" states that the most accurate message is the message of the minimum length.

Albert Einstein reformulated the principle of "Occam's Razor" as follows: "Everything should be simplified as long as possible, but no more."

3. About the beginning of understanding and representation by mankind of thermonuclear fusion on the Sun

All the inhabitants of the Earth for a long time understood the fact that the Sun warms the Earth, but the sources of solar energy remained incomprehensible to everyone. In 1848, Robert Meyer put forward the meteorite hypothesis, according to which the Sun is heated by the bombardment of meteorites. However, with such a necessary number of meteorites, the Earth would also be very hot; in addition, the terrestrial geological strata would consist mainly of meteorites; finally, the mass of the Sun had to increase, and this would affect the movement of the planets.

Therefore, in the second half of the 19th century, many researchers considered the most plausible theory developed by Helmholtz (1853) and Lord Kelvin, who suggested that the Sun heats up due to slow gravitational contraction (“Kelvin-Helmholtz mechanism”). Calculations based on this mechanism estimated the maximum age of the Sun at 20 million years, and the time after which the Sun will go out - no more than 15 million years. However, this hypothesis contradicted the geological data on the age of rocks, which indicated much larger numbers. For example, Charles Darwin noted that the erosion of the Vendian deposits lasted at least 300 million years. Nevertheless, the Brockhaus and Efron Encyclopedia considers the gravitational model the only acceptable one.

Only in the 20th century was the “correct” solution to this problem found. Initially, Rutherford put forward the hypothesis that the source of the internal energy of the Sun is radioactive decay. In 1920, Arthur Eddington suggested that the pressure and temperature in the interior of the Sun are so high that thermonuclear reactions can take place there, in which hydrogen nuclei (protons) merge into a helium-4 nucleus. Since the mass of the latter is less than the sum of the masses of four free protons, then part of the mass in this reaction, according to Einstein's formula E = mc 2 is converted into energy. The fact that hydrogen predominates in the composition of the Sun was confirmed in 1925 by Cecilly Payne.

The theory of nuclear fusion was developed in the 1930s by astrophysicists Chandrasekhar and Hans Bethe. Bethe calculated in detail the two main thermonuclear reactions that are the sources of the Sun's energy. Finally, in 1957, Margaret Burbridge's work "Synthesis of Elements in Stars" appeared, in which it was shown, it was suggested that most of the elements in the Universe arose as a result of nucleosynthesis going on in stars.

4. Space exploration of the Sun

The first works of Eddington as an astronomer are connected with the study of the movements of stars and the structure of stellar systems. But, his main merit is that he created the theory of the internal structure of stars. Deep insight into the physical essence of phenomena and mastery of the methods of the most complex mathematical calculations allowed Eddington to obtain a number of fundamental results in such areas of astrophysics as the internal structure of stars, the state of interstellar matter, the motion and distribution of stars in the Galaxy.

Eddington calculated the diameters of some red giant stars, determined the density of the dwarf satellite of the star Sirius - it turned out to be unusually high. Eddington's work on determining the density of a star served as an impetus for the development of the physics of superdense (degenerate) gas. Eddington was a good interpreter general theory Einstein's relativity. He made the first experimental test of one of the effects predicted by this theory: the deflection of light rays in the gravitational field of a massive star. He managed to do this during a total eclipse of the Sun in 1919. Together with other scientists, Eddington laid the foundations of modern knowledge about the structure of stars.

5. Thermonuclear fusion - combustion!?

What is, visually, thermonuclear fusion? Basically, it's combustion. But it is clear that this is combustion of a very high power per unit volume of space. And it is clear that this is not an oxidation process. Here, in the combustion process, other elements are involved, which also burn, but under special physical conditions.

Consider combustion.

Chemical combustion is a complex physical and chemical process of converting the components of a combustible mixture into combustion products with the release of thermal radiation, light and radiant energy.

Chemical combustion is divided into several types of combustion.

Subsonic combustion (deflagration), unlike explosion and detonation, proceeds at low speeds and is not associated with the formation of a shock wave. Subsonic combustion includes normal laminar and turbulent flame propagation, and supersonic combustion refers to detonation.

Combustion is divided into thermal and chain. Thermal combustion is based on a chemical reaction capable of proceeding with progressive self-acceleration due to the accumulation of released heat. Chain combustion occurs in some gas-phase reactions at low pressures.

Thermal self-acceleration conditions can be provided for all reactions with sufficiently large thermal effects and activation energies.

Combustion can start spontaneously as a result of self-ignition or be initiated by ignition. Under fixed external conditions, continuous combustion can proceed in a stationary mode, when the main characteristics of the process - the reaction rate, heat release rate, temperature and product composition - do not change over time, or in a periodic mode, when these characteristics fluctuate around their average values. Due to the strong nonlinear dependence of the reaction rate on temperature, combustion is highly sensitive to external conditions. The same property of combustion determines the existence of several stationary regimes under the same conditions (hysteresis effect).

There is volumetric combustion, it is well known and often used in everyday life.

diffusion combustion. It is characterized by separate supply of fuel and oxidizer to the combustion zone. Mixing of components takes place in the combustion zone. Example: combustion of hydrogen and oxygen in a rocket engine.

Combustion of a premixed medium. As the name implies, combustion occurs in a mixture in which both fuel and oxidizer are present. Example: combustion in the cylinder of an internal combustion engine of a gasoline-air mixture after the initialization of the process with a spark plug.

Flameless combustion. In contrast to conventional combustion, when zones of oxidizing flame and reducing flame are observed, it is possible to create conditions for flameless combustion. An example is the catalytic oxidation of organic substances on the surface of a suitable catalyst, for example, the oxidation of ethanol on platinum black.

Smoldering. A type of combustion in which no flame is formed, and the combustion zone slowly spreads through the material. Smoldering is commonly seen with porous or fibrous materials with a high air content or impregnated with oxidizing agents.

autogenous combustion. Self-sustaining combustion. The term is used in waste incineration technologies. The possibility of autogenous (self-sustaining) combustion of waste is determined by the maximum content of ballasting components: moisture and ash.

Flame is a region of space in which combustion occurs in the gas phase, accompanied by visible and (or) infrared radiation.

The usual flame that we observe when burning a candle, the flame of a lighter or a match, is a stream of hot gases, stretched vertically due to the Earth's gravity (hot gases tend to rise up).

6. Modern physical and chemical ideas about the Sun

Main characteristics:

The composition of the photosphere:

The Sun is the central and only star of our solar system, around which other objects of this system revolve: planets and their satellites, dwarf planets and their satellites, asteroids, meteoroids, comets and cosmic dust. The mass of the Sun (theoretically) is 99.8% of the total mass of the entire solar system. Solar radiation supports life on Earth (photons are necessary for the initial stages of the photosynthesis process), determines the climate.

According to the spectral classification, the Sun belongs to the type G2V (“yellow dwarf”). The surface temperature of the Sun reaches 6000 K, so the Sun shines with almost white light, but due to stronger scattering and absorption of the short-wavelength part of the spectrum by the Earth's atmosphere, the direct light of the Sun near the surface of our planet acquires a certain yellow tint.

The solar spectrum contains lines of ionized and neutral metals, as well as ionized hydrogen. There are approximately 100 million G2 stars in our Milky Way galaxy. At the same time, 85% of the stars in our galaxy are stars that are less bright than the Sun (most of them are red dwarfs at the end of their evolution cycle). Like all main-sequence stars, the Sun generates energy through nuclear fusion.

Solar radiation is the main source of energy on Earth. Its power is characterized by the solar constant - the amount of energy passing through the area of ​​​​a unit area, perpendicular to the sun's rays. At a distance of one astronomical unit (that is, in the orbit of the Earth), this constant is approximately 1370 W/m 2 .

Passing through the Earth's atmosphere, solar radiation loses approximately 370 W / m 2 in energy, and only 1000 W / m 2 reaches the earth's surface (in clear weather and when the Sun is at its zenith). This energy can be used in various natural and artificial processes. So, plants with the help of photosynthesis process it into a chemical form (oxygen and organic compounds). Direct heating from the sun's rays or energy conversion using photovoltaic cells can be used to generate electricity (solar power plants) or perform other useful work. In the distant past, the energy stored in oil and other fossil fuels was also obtained through photosynthesis.

The sun is a magnetically active star. It has a strong magnetic field that changes over time and changes direction approximately every 11 years, during solar maximum. Variations in the magnetic field of the Sun cause a variety of effects, the totality of which is called solar activity and includes such phenomena as sunspots, solar flares, solar wind variations, etc., and on Earth it causes auroras in high and middle latitudes and geomagnetic storms, which adversely affect the operation of communication facilities, means of transmitting electricity, and also negatively affects living organisms, causing headaches and poor health in people (for people who are sensitive to magnetic storms). The Sun is a young star of the third generation (population I) with a high content of metals, that is, it was formed from the remains of stars of the first and second generations (populations III and II, respectively).

The current age of the Sun (more precisely, the time of its existence on the main sequence), estimated using computer models of stellar evolution, is approximately 4.57 billion years.

Life cycle of the sun. The Sun is believed to have formed about 4.59 billion years ago when a cloud of molecular hydrogen rapidly compressed under the action of gravity forces to form a star of the first type of stellar population of the T Taurus type in our region of the Galaxy.

A star of the same mass as the Sun should exist on the main sequence for a total of about 10 billion years. Thus, now the Sun is approximately in the middle of its life cycle. On present stage Thermonuclear reactions are taking place in the solar core, converting hydrogen into helium. Every second in the core of the Sun, about 4 million tons of matter is converted into radiant energy, resulting in the generation of solar radiation and a stream of solar neutrinos.

7. Theoretical ideas of mankind about the internal and external structure of the Sun

At the center of the Sun is the solar core. The photosphere is the visible surface of the Sun, which is the main source of radiation. The sun is surrounded by a solar corona, which has a very high temperature, but it is extremely rarefied, therefore it is visible to the naked eye only during periods of complete solar eclipse.

The central part of the Sun with a radius of about 150,000 kilometers, in which thermonuclear reactions take place, is called the solar core. The density of matter in the core is about 150,000 kg/m A theoretical analysis of the data, carried out by the SOHO mission, showed that in the core the speed of rotation of the Sun around its axis is much higher than on the surface. A proton-proton thermonuclear reaction takes place in the nucleus, as a result of which helium-4 is formed from four protons. At the same time, 4.26 million tons of matter are converted into energy every second, but this value is negligible compared to the mass of the Sun - 2·10 27 tons.

Above the core, at distances of about 0.2 ... 0.7 of the Sun's radius from its center, there is a radiative transfer zone in which there are no macroscopic movements, energy is transferred with the help of "re-emission" of photons.

convective zone of the sun. Closer to the surface of the Sun, vortex mixing of the plasma occurs, and the transfer of energy to the surface occurs mainly by the motions of the matter itself. This method of energy transfer is called convection, and the subsurface layer of the Sun, approximately 200,000 km thick, where it occurs, is called the convective zone. According to modern data, its role in the physics of solar processes is exceptionally great, since it is in it that various motions of solar matter and magnetic fields originate.

Atmosphere of the Sun The photosphere (a layer that emits light) reaches a thickness of ≈320 km and forms the visible surface of the Sun. The main part of the optical (visible) radiation of the Sun comes from the photosphere, while the radiation from deeper layers no longer reaches it. The temperature in the photosphere reaches an average of 5800 K. Here, the average density of the gas is less than 1/1000 of the density of terrestrial air, and the temperature decreases to 4800 K as it approaches the outer edge of the photosphere. Under such conditions, hydrogen remains almost completely in a neutral state. The photosphere forms the visible surface of the Sun, from which the dimensions of the Sun, the distance from the surface of the Sun, etc. are determined. The chromosphere is the outer shell of the Sun, about 10,000 km thick, surrounding the photosphere. The origin of the name of this part of the solar atmosphere is associated with its reddish color, caused by the fact that its visible spectrum is dominated by the red H-alpha emission line of hydrogen. The upper boundary of the chromosphere does not have a pronounced smooth surface; hot ejections, called spicules, constantly occur from it (because of this, at the end of the 19th century, the Italian astronomer Secchi, observing the chromosphere through a telescope, compared it with burning prairies). The temperature of the chromosphere increases with altitude from 4,000 to 15,000 degrees.

The density of the chromosphere is low, so its brightness is insufficient to observe it under normal conditions. But during a total solar eclipse, when the Moon covers the bright photosphere, the chromosphere located above it becomes visible and glows red. It can also be observed at any time using special narrow-band optical filters.

The corona is the last outer shell of the sun. Despite its very high temperature, from 600,000 to 2,000,000 degrees, it is visible to the naked eye only during a total solar eclipse, since the density of matter in the corona is low, and therefore its brightness is also low. The unusually intense heating of this layer is apparently caused by the magnetic effect and the action of shock waves. The shape of the corona changes depending on the phase of the solar activity cycle: during periods of maximum activity, it has a rounded shape, and at minimum, it is elongated along the solar equator. Since the temperature of the corona is very high, it radiates intensely in the ultraviolet and X-ray ranges. These radiations do not pass through the earth's atmosphere, but in Lately it became possible to study them with the help of spacecraft. Radiation in different regions of the corona occurs unevenly. There are hot active and quiet regions, as well as coronal holes with a relatively low temperature of 600,000 degrees, from which magnetic field lines emerge into space. This ("open") magnetic configuration allows particles to leave the Sun unhindered, so the solar wind is emitted "primarily" from coronal holes.

From the outer part of the solar corona, the solar wind flows out - a stream of ionized particles (mainly protons, electrons and α-particles), having a speed of 300 ... 1200 km / s and propagating, with a gradual decrease in its density, to the boundaries of the heliosphere.

Since the solar plasma has a sufficiently high electrical conductivity, electric currents and, as a result, magnetic fields can arise in it.

8. Theoretical problems of thermonuclear fusion on the Sun

The problem of solar neutrinos. Nuclear reactions occurring in the core of the Sun lead to the formation of a large number of electron neutrinos. At the same time, measurements of the neutrino flux on Earth, which have been constantly made since the late 1960s, showed that the number of solar electron neutrinos recorded there is approximately two to three times less than predicted by the standard solar model describing processes in the Sun. This discrepancy between experiment and theory has been called the "solar neutrino problem" and has been one of the mysteries of solar physics for more than 30 years. The situation was complicated by the fact that neutrinos interact extremely weakly with matter, and the creation of a neutrino detector that can accurately measure the neutrino flux even of such a power as coming from the Sun is a rather difficult scientific task.

Two main ways of solving the problem of solar neutrinos have been proposed. First, it was possible to modify the model of the Sun in such a way as to reduce the assumed temperature in its core and, consequently, the flux of neutrinos emitted by the Sun. Secondly, it could be assumed that some of the electron neutrinos emitted by the core of the Sun, when moving towards the Earth, turn into neutrinos of other generations (muon and tau neutrinos) that are not detected by conventional detectors. Today, scientists are inclined to believe that the second way is most likely the correct one. In order for the transition of one type of neutrino to another - the so-called "neutrino oscillations" - to take place, the neutrino must have a non-zero mass. It has now been established that this seems to be true. In 2001, all three types of solar neutrinos were directly detected at the Sudbury Neutrino Observatory and their total flux was shown to be consistent with the Standard Solar Model. In this case, only about a third of the neutrinos reaching the Earth turn out to be electronic. This number is consistent with the theory that predicts the transition of electron neutrinos into neutrinos of another generation both in vacuum (actually "neutrino oscillations") and in solar matter ("Mikheev-Smirnov-Wolfenstein effect"). Thus, at present, the problem of solar neutrinos seems to have been solved.

Corona heating problem. Above the visible surface of the Sun (photosphere), which has a temperature of about 6,000 K, is the solar corona with a temperature of more than 1,000,000 K. It can be shown that the direct flow of heat from the photosphere is not enough to lead to such a high temperature of the corona.

It is assumed that the energy for heating the corona is supplied by turbulent motions of the subphotospheric convective zone. In this case, two mechanisms have been proposed for energy transfer to the corona. Firstly, this is wave heating - sound and magnetohydrodynamic waves generated in the turbulent convective zone propagate into the corona and dissipate there, while their energy is converted into thermal energy of the coronal plasma. An alternative mechanism is magnetic heating, in which the magnetic energy continuously generated by photospheric motions is released by reconnecting the magnetic field in the form of large solar flares or a large number of small flares.

At present, it is not clear what type of waves provides an efficient mechanism for heating the corona. It can be shown that all waves, except for magnetohydrodynamic Alfven ones, are scattered or reflected before they reach the corona, while the dissipation of Alfvén waves in the corona is difficult. Therefore, modern researchers have focused on the mechanism of heating with the help of solar flares. One of the possible candidates for sources of coronal heating is continuously occurring small-scale flares, although final clarity on this issue has not yet been achieved.

P.S. After reading about "Theoretical Problems of Thermonuclear Fusion in the Sun" it is necessary to remember "Occam's Razor". Here, far-fetched illogical theoretical explanations are clearly used in explanations of theoretical problems.

9. Types of thermonuclear fuel. thermonuclear fuel

Controlled thermonuclear fusion (CTF) is the synthesis of heavier atomic nuclei from lighter ones in order to obtain energy, which, unlike explosive thermonuclear fusion (used in thermonuclear weapons), is controlled. Controlled thermonuclear fusion is different from traditional nuclear power the fact that the latter uses a decay reaction, during which lighter nuclei are obtained from heavy nuclei. The main nuclear reactions planned to be used for controlled fusion will use deuterium (2 H) and tritium (3 H), and in the longer term helium-3 (3 He) and boron-11 (11 B)

Types of reactions. The fusion reaction is as follows: two or more atomic nuclei are taken and, with the application of a certain force, they approach so much that the forces acting at such distances prevail over the Coulomb repulsion forces between equally charged nuclei, as a result of which a new nucleus is formed. It will have a slightly smaller mass than the sum of the masses of the original nuclei, and the difference becomes the energy that is released during the reaction. The amount of energy released is described by the well-known formula E = mc 2. Lighter atomic nuclei are easier to bring to the right distance, so hydrogen - the most abundant element in the universe - is the best fuel for a fusion reaction.

It has been established that a mixture of two isotopes of hydrogen, deuterium and tritium, requires the least amount of energy for the fusion reaction compared to the energy released during the reaction. However, although a mixture of deuterium and tritium (D-T) is the subject of most fusion research, it is by no means the only potential fuel. Other mixtures may be easier to manufacture; their reaction can be better controlled, or more importantly, produce fewer neutrons. Of particular interest are the so-called "neutronless" reactions, since the successful industrial use of such fuel will mean the absence of long-term radioactive contamination of materials and reactor design, which, in turn, could positively affect public opinion and the overall cost of operating the reactor, significantly reducing the cost of decommissioning it. The problem remains that the fusion reaction using alternative fuels is much more difficult to maintain, so the D-T reaction is considered only a necessary first step.

Scheme of the deuterium-tritium reaction. Controlled thermonuclear fusion can use different kinds thermonuclear reactions depending on the type of fuel used.

The most easily implemented reaction is deuterium + tritium:

2 H + 3 H = 4 He + n with an energy output of 17.6 MeV.

Such a reaction is most easily implemented from the point of view of modern technologies, gives a significant yield of energy, and fuel components are cheap. Its disadvantage is the release of unwanted neutron radiation.

Two nuclei: deuterium and tritium fuse to form a helium nucleus (alpha particle) and a high-energy neutron.

The reaction - deuterium + helium-3 is much more difficult, at the limit of what is possible, to carry out the reaction deuterium + helium-3:

2 H + 3 He = 4 He + p with an energy output of 18.3 MeV.

The conditions for achieving it are much more complicated. Helium-3 is also a rare and extremely expensive isotope. It is currently not produced on an industrial scale.

Reaction between deuterium nuclei (D-D, monopropellant).

Reactions between deuterium nuclei are also possible, they are a little more difficult than reactions involving helium-3.

These reactions slowly proceed in parallel with the reaction of deuterium + helium-3, and the tritium and helium-3 formed during them are very likely to immediately react with deuterium.

Other types of reactions. Several other types of reactions are also possible. The choice of fuel depends on many factors - its availability and low cost, energy yield, ease of achieving the conditions required for the fusion reaction (primarily temperature), the necessary design characteristics of the reactor, and so on.

"Neutronless" reactions. The most promising so-called. "neutronless" reactions, since the neutron flux generated by thermonuclear fusion (for example, in the deuterium-tritium reaction) carries away a significant part of the power and generates induced radioactivity in the reactor design. The deuterium-helium-3 reaction is promising, also due to the lack of a neutron yield.

10. Classical ideas about the conditions of implementation. thermonuclear fusion and controlled thermonuclear reactors

TOKAMAK (TOROIDAL CAMERA WITH MAGNETIC COILS) is a toroidal facility for magnetic plasma confinement. The plasma is held not by the walls of the chamber, which are not able to withstand its temperature, but by a specially created magnetic field. A feature of TOKAMAK is the use electric current, flowing through the plasma to create the poloidal field necessary for plasma equilibrium.

CTS is possible with the simultaneous fulfillment of two criteria:

• the plasma temperature must be greater than 100,000,000 K;
• compliance with the Lawson criterion: n · t> 5 10 19 cm -3 s (for the D-T reaction),
  Where n is the high-temperature plasma density, t is the plasma confinement time in the system.

It is believed, theoretically, that it is the value of these two criteria that mainly determines the rate of a particular thermonuclear reaction.

At present, controlled thermonuclear fusion has not yet been carried out on an industrial scale. Although developed countries have built, in general, several dozen controlled thermonuclear reactors, they cannot provide controlled thermonuclear fusion. The construction of the international research reactor ITER is in its initial stages.

Two principal schemes for the implementation of controlled thermonuclear fusion are considered.

Quasi-stationary systems. The plasma is heated and held by a magnetic field at a relatively low pressure and high temperature. For this, reactors in the form of TOKAMAKS, stellarators, mirror traps and torsatrons are used, which differ in the configuration of the magnetic field. The ITER reactor has a TOKAMAK configuration.

impulse systems. In such systems, CTS is carried out by short-term heating of small targets containing deuterium and tritium by ultra-high-power laser or ion pulses. Such irradiation causes a sequence of thermonuclear microexplosions.

Studies of the first type of thermonuclear reactors are much more developed than those of the second. In nuclear physics, in the study of thermonuclear fusion, a magnetic trap is used to hold plasma in a certain volume. The magnetic trap is designed to keep the plasma from contact with the elements of a thermonuclear reactor, i.e. used primarily as a heat insulator. The confinement principle is based on the interaction of charged particles with a magnetic field, namely, on the rotation of charged particles around the magnetic field lines. Unfortunately, the magnetized plasma is very unstable and tends to leave the magnetic field. Therefore, to create an effective magnetic trap, the most powerful electromagnets are used, which consume a huge amount of energy.

It is possible to reduce the size of a thermonuclear reactor if three methods of creating a thermonuclear reaction are used simultaneously in it.

inertial synthesis. Irradiate tiny capsules of deuterium-tritium fuel with a laser with a power of 500 trillion (5 10 14) watts. This giant, very short-term 10–8 s laser pulse causes the fuel capsules to explode, resulting in the birth of a mini-star for a fraction of a second. But a thermonuclear reaction cannot be achieved on it.

Simultaneously use Z-machine with TOKAMAK. A Z-machine works differently than a laser. It passes through a web of the thinnest wires surrounding the fuel capsule, a charge with a power of half a trillion watts 5 10 11 watts.

The first generation reactors will most likely run on a mixture of deuterium and tritium. The neutrons that appear during the reaction will be absorbed by the reactor shield, and the heat released will be used to heat the coolant in the heat exchanger, and this energy, in turn, will be used to rotate the generator.

There are, in theory, alternative types of fuel that are devoid of these disadvantages. But their use is hindered by a fundamental physical limitation. To get enough energy from the fusion reaction, it is necessary to keep a sufficiently dense plasma at the fusion temperature (10 8 K) for a certain time.

This fundamental aspect of synthesis is described by the product of the plasma density n for the time of maintenance of the heated plasma τ, which is required to reach the equilibrium point. Work nτ depends on the type of fuel and is a function of the plasma temperature. Of all types of fuel, the deuterium-tritium mixture requires the lowest value nτ by at least an order of magnitude, and the lowest reaction temperature by at least 5 times. Thus, D-T reaction is a necessary first step, but the use of other fuels remains an important research goal.

11. Fusion reaction as an industrial source of electricity

Fusion energy is considered by many researchers as a "natural" source of energy in the long term. Proponents of the commercial use of fusion reactors for power generation make the following arguments in their favor:

• practically inexhaustible reserves of fuel (hydrogen);
• fuel can be obtained from sea ​​water on any coast of the world, which makes it impossible for one or a group of countries to monopolize fuel;
• the impossibility of an uncontrolled synthesis reaction;
• absence of combustion products;
• there is no need to use materials that can be used to produce nuclear weapons, thus eliminating cases of sabotage and terrorism;
• compared to nuclear reactors, a small amount of radioactive waste is produced with a short half-life.

It is estimated that a thimble filled with deuterium produces the energy equivalent of 20 tons of coal. A medium-sized lake is able to provide any country with energy for hundreds of years. However, it should be noted that existing research reactors are designed to achieve a direct deuterium-tritium (DT) reaction, whose fuel cycle requires the use of lithium to produce tritium, while claims of inexhaustible energy refer to the use of a deuterium-deuterium (DD) reaction in the second generation of reactors.

Just like the fission reaction, the fusion reaction produces no atmospheric emissions of carbon dioxide, a major contributor to global warming. This is a significant advantage, since the use of fossil fuels for electricity generation has the effect that, for example, the US produces 29 kg of CO 2 (one of the main gases that can be considered a cause of global warming) per US inhabitant per day.

12. Already have doubts

The countries of the European Community spend about 200 million euros annually on research, and it is predicted that it will take several more decades before the industrial use of nuclear fusion becomes possible. Supporters of alternative sources of electricity believe that it would be more appropriate to use these funds for the introduction of renewable sources of electricity.

Unfortunately, despite the widespread optimism (common since the 1950s, when the first research began), significant obstacles between today's understanding of nuclear fusion processes, technological possibilities and the practical use of nuclear fusion have not yet been overcome, it is unclear even how much can be economically profitable production of electricity using thermonuclear fusion. Although progress in research is constant, researchers are constantly faced with new challenges. For example, the challenge is to develop a material that can withstand neutron bombardment, which is estimated to be 100 times more intense than conventional nuclear reactors.

13. The classic idea of ​​the upcoming stages in the creation of a controlled thermonuclear reactor

There are the following stages in research.

Equilibrium or "pass" mode: when the total energy that is released during the fusion process is equal to the total energy spent on starting and supporting the reaction. This ratio is marked with the symbol Q. The equilibrium of the reaction was demonstrated at the JET in the UK in 1997. Having spent 52 MW of electricity to heat it up, the scientists received a power output that was 0.2 MW higher than that spent. (You need to double-check this data!)

Blazing Plasma: an intermediate stage in which the reaction will be supported mainly by alpha particles that are produced during the reaction, and not by external heating.

Q≈ 5. So far, the intermediate stage has not been reached.

Ignition: a stable response that sustains itself. Should be achieved with large values Q. So far not achieved.

The next step in research should be ITER, the International Thermonuclear Experimental Reactor. At this reactor, it is planned to study the behavior of high-temperature plasma (flaming plasma with Q≈ 30) and structural materials for an industrial reactor.

The final phase of the research will be DEMO: a prototype industrial reactor that will achieve ignition and demonstrate the practical suitability of new materials. The most optimistic forecasts for the completion of the DEMO phase: 30 years. Taking into account the approximate time for the construction and commissioning of an industrial reactor, we are separated by ≈40 years from the industrial use of thermonuclear energy.

14. All this needs to be considered

Dozens, and maybe hundreds of experimental thermonuclear reactors of various sizes have been built in the world. Scientists come to work, turn on the reactor, the reaction takes place quickly, it seems, they turn it off, and they sit and think. What is the reason? What to do next? And so for decades, to no avail.

So, the history of human understanding about thermonuclear fusion on the Sun and the history of mankind's achievements in creating a controlled thermonuclear reactor were outlined above.

A long way has been passed and a lot has been done to achieve the final goal. But, unfortunately, the result is negative. A controlled thermonuclear reactor has not been created. Another 30 ... 40 years and the promises of scientists will be fulfilled. Will they? 60 years no result. Why should it happen in 30...40 years, and not in three years?

There is another idea of ​​thermonuclear fusion in the Sun. It is logical, simple and really leads to a positive result. This discovery by V.F. Vlasov. Thanks to this discovery, even TOKAMAKS can start operating in the near future.

15. A new look at the nature of thermonuclear fusion in the Sun and the invention "Method of controlled thermonuclear fusion and controlled thermonuclear reactor for controlled thermonuclear fusion"

From the author. This discovery and invention is almost 20 years old. For a long time I doubted that I had found a new way to carry out thermonuclear fusion and for its implementation a new thermonuclear reactor. I have researched and studied hundreds of papers in the field of thermonuclear fusion. Time and processed information convinced me that I was on the right track.

At first glance, the invention is very simple and does not at all look like an experimental thermonuclear reactor of the TOKAMAK type. In modern ideas of authorities from the science of TOKAMAK, this is the only correct decision and is not subject to discussion. 60 years of the idea of ​​a thermonuclear reactor. But a positive result - a working thermonuclear reactor with controlled thermonuclear fusion TOKAMAK - is promised only in 30...40 years. Probably, if there is no real positive result for 60 years, then the chosen method of technical solution of the idea - the creation of a controlled thermonuclear reactor - is, to put it mildly, incorrect, or not realistic enough. Let's try to show that there is another solution to this idea based on the discovery of thermonuclear fusion in the Sun, and it differs from the generally accepted ideas.

Opening. The main idea of ​​the opening is very simple and logical, and lies in the fact that thermonuclear reactions occur in the region of the solar corona. It is here that the necessary physical conditions exist for the implementation of a thermonuclear reaction. From the solar corona, where the plasma temperature is approximately 1,500,000 K, the surface of the Sun heats up to 6,000 K, from here the fuel mixture evaporates into the solar corona from the boiling surface of the Sun. Temperatures of 6,000 K are enough for the fuel mixture in the form of evaporating vapors to overcome the gravitational force of the sun. This protects the surface of the Sun from overheating and maintains the temperature of its surface.

Near the burning zone - the solar corona, there are physical conditions under which the sizes of atoms should change and, at the same time, the Coulomb forces should significantly decrease. Upon contact, the atoms of the fuel mixture merge and synthesize new elements with a large release of heat. This combustion zone creates the solar corona, from which energy in the form of radiation and matter enters outer space. The fusion of deuterium and tritium is helped by the magnetic field of the rotating Sun, where they are mixed and accelerated. Also from the thermonuclear reaction zone in the solar corona, fast electrically charged particles appear and move with great energy towards the evaporating fuel, as well as photons - electromagnetic field quanta, all this creates the necessary physical conditions for thermonuclear fusion.

In the classical concepts of physicists, thermonuclear fusion, for some reason, is not attributed to the combustion process (this does not mean the oxidative process). Authorities from physics came up with the idea that thermonuclear fusion on the Sun repeats the volcanic process on a planet, for example, Earth. Hence all the reasoning, the method of similarity is used. There is no evidence that the core of the planet Earth has a molten liquid state. Even geophysics cannot reach such depths. The existence of volcanoes cannot be taken as proof of the liquid core of the Earth. In the bowels of the Earth, especially at shallow depths, there are physical processes that are still unknown to authoritative physicists. In physics, there is not a single proof that thermonuclear fusion occurs in the depths of any star. And in a thermonuclear bomb, thermonuclear fusion does not at all repeat the model in the bowels of the Sun.

Upon careful visual study, the Sun looks like a spherical volumetric burner and very much resembles burning on a large surface of the earth, where there is a gap between the surface boundary and the burning zone (a prototype of the solar corona) through which thermal radiation is transmitted to the earth's surface, which evaporates, for example, spilled fuel and these prepared vapors enter the combustion zone.

It is clear that on the surface of the Sun, such a process occurs under other, other physical conditions. Similar physical conditions, quite close in terms of parameters, were included in the development of the design of a controlled thermonuclear reactor, Short description and the schematic diagram of which is set out in the patent application set forth below.

Abstract of the patent application No. 2005123095/06(026016).

"Method of controlled thermonuclear fusion and controlled thermonuclear reactor for the implementation of controlled thermonuclear fusion".

I explain the method and principle of operation of the declared controlled thermonuclear reactor for the implementation of controlled thermonuclear fusion.

Rice. 1. Simplified circuit diagram UTYAR

On fig. 1 shows a schematic diagram of the UTYAR. Fuel mixture, in a mass ratio of 1:10, compressed to 3000 kg / cm 2 and heated to 3000 ° C, in the zone 1 mixes and enters through the critical section of the nozzle into the expansion zone 2 . In the zone 3 fuel mixture is ignited.

The temperature of the ignition spark can be any temperature necessary to start the thermal process - from 109...108 K and below, it depends on the necessary physical conditions created.

In the high temperature zone 4 the combustion process takes place. Combustion products transfer heat in the form of radiation and convection to the heat exchange system 5 and towards the incoming fuel mixture. Device 6 in the active part of the reactor from the critical section of the nozzle to the end of the combustion zone helps to change the magnitude of the Coulomb forces and increases the effective cross section of the fuel mixture nuclei (creates the necessary physical conditions).

The diagram shows that the reactor is similar to gas burner. But a thermonuclear reactor should be like that, and of course, the physical parameters will differ by hundreds of times from, for example, the physical parameters of a gas burner.

Repetition of the physical conditions of thermonuclear fusion on the Sun in terrestrial conditions - this is the essence of the invention.

Any heat generating device that uses combustion must create the following conditions - cycles: fuel preparation, mixing, supply to the working zone (combustion zone), ignition, combustion (chemical or nuclear transformation), heat removal from hot gases in the form of radiation and convection, and removal of combustion products. In case of hazardous waste - their disposal. All of this is covered in the pending patent.

The main argument of physicists about the fulfillment of the Lawsen criterion is fulfilled - during ignition by an electric spark or a laser beam, as well as fast electric charged particles reflected from the combustion zone to evaporating fuel, as well as photons - electromagnetic field quanta with high-density energies, a temperature of 109 .. .108 K for a certain minimum area of ​​the fuel, in addition, the density of the fuel will be 10 14 cm -3 . Isn't this a way and method to fulfill the Lawsen criterion. But all these physical parameters can change under the influence of external factors on some other physical parameters. This is still know-how.

Let us consider the reasons for the impossibility of implementing thermonuclear fusion in known thermonuclear reactors.

16. Disadvantages and problems of generally accepted ideas in physics about thermonuclear reaction on the Sun

1. Known. The temperature of the visible surface of the Sun - the photosphere - is 5800 K. The density of gas in the photosphere is thousands of times less than the density of air near the Earth's surface. It is generally accepted that inside the Sun temperature, density and pressure increase with depth, reaching 16 million K in the center (some say 100 million K), 160 g/cm 3 and 3.5 10 11 bar. Under the influence of high temperature in the core of the Sun, hydrogen turns into helium with the release of a large amount of heat. So, it is believed that the temperature inside the Sun is from 16 to 100 million degrees, on the surface 5800 degrees, and in the solar corona from 1 to 2 million degrees? Why such nonsense? No one can explain this in a clear and understandable way. The well-known generally accepted explanations are flawed and do not give a clear and sufficient idea of ​​the reasons for the violation of the laws of thermodynamics on the Sun.

2. A thermonuclear bomb and a thermonuclear reactor operate on different technological principles, i.e. similarly similar. It is impossible to create a thermonuclear reactor in the likeness of a thermonuclear bomb, which is missed in the development of modern experimental thermonuclear reactors.

3. In 1920, the authoritative physicist Eddington cautiously suggested the nature of a thermonuclear reaction in the Sun, that the pressure and temperature in the bowels of the Sun are so high that thermonuclear reactions can take place there, in which hydrogen nuclei (protons) merge into a helium-4 nucleus. This is currently the generally accepted view. But since then, there is no evidence that thermonuclear reactions occur in the core of the Sun at 16 million K (some physicists believe 100 million K), a density of 160 g / cm3 and a pressure of 3.5 x 1011 bar, there are only theoretical assumptions . Thermonuclear reactions in the solar corona are evident. It is easy to detect and measure.

4. The problem of solar neutrinos. Nuclear reactions occurring in the core of the Sun lead to the formation of a large number of electron neutrinos. The formation, transformations and number of solar neutrinos, according to the old ideas, are not explained clearly and several decades are enough. There are no such theoretical difficulties in the new concepts of thermonuclear fusion on the Sun.

5. Corona heating problem. Above the visible surface of the Sun (photosphere), which has a temperature of about 6000 K, is the solar corona with a temperature of more than 1,500,000 K. It can be shown that the direct flow of heat from the photosphere is not enough to lead to such a high temperature of the corona. A new understanding of thermonuclear fusion in the Sun explains the nature of such a temperature of the solar corona. This is where thermonuclear reactions take place.

6. Physicists forget that TOKAMAKS are mainly needed to contain high-temperature plasma and nothing more. The existing and being created TOKAMAKS do not provide for the creation of the necessary, special, physical conditions for conducting thermonuclear fusion. For some reason no one understands this. Everyone stubbornly believes that deuterium and tritium should burn well at temperatures of many millions. Why would suddenly? A nuclear target just quickly explodes, not burns. Look closely at how nuclear combustion occurs in TOKAMAK. Such a nuclear explosion can only hold the strong magnetic field of the reactor very large sizes(easily calculated), but then the efficiency such a reactor would be unacceptable for technical application. In the pending patent, the problem of confining fusion plasma is easily solved.

Explanations of scientists about the processes that occur in the bowels of the Sun are insufficient for understanding thermonuclear fusion in depth. No one has considered the processes of fuel preparation, the processes of heat and mass transfer, at depth, in very difficult critical conditions, well enough. For example, how, under what conditions, is plasma formed at a depth in which thermonuclear fusion occurs? How she behaves, etc. After all, TOKAMAKS are technically arranged in this way.

So, a new idea of ​​thermonuclear fusion solves all the existing technical and theoretical problems in this area.

P.S. Difficult to offer simple truths people who for decades believed in the opinions (assumptions) of scientific authorities. To understand what the new discovery is about, it is enough to independently review what has been a dogma for many years. If a new proposition about the nature of a physical effect raises doubts about the truth of the old assumptions, prove the truth to yourself first. This is what every true scientist should do. The discovery of thermonuclear fusion in the solar corona is proved primarily visually. Thermonuclear combustion occurs not in the bowels of the Sun, but on its surface. This is a special fire. In many photographs and images of the Sun, you can see how the combustion process is going on, how the process of plasma formation is going on.

1. Controlled thermonuclear fusion. Wikipedia.

2. Velikhov E.P., Mirnov S.V. Controlled thermonuclear fusion is entering the finish line. Troitsk Institute for Innovation and Thermonuclear Research. Russian science Center"Kurchatov Institute", 2006.

3. Llewellyn-Smith K. On the way to thermonuclear power engineering. Materials of the lecture given on May 17, 2009 at FIAN.

4. Encyclopedia of the Sun. Tesis, 2006.

5. Sun. Astronet.

6. The sun and the life of the Earth. Radio communication and radio waves.

7. Sun and Earth. Uniform fluctuations.

8. Sun. solar system. General astronomy. Project "Astrogalaxy".

9. Journey from the center of the Sun. Popular Mechanics, 2008.

10. Sun. Physical encyclopedia.

11. Astronomy Picture of the Day.

12. Combustion. Wikipedia.

"Science and Technology"

>What is the Sun made of?

Find out, what is the sun made of: a description of the structure and composition of the star, a list of chemical elements, the number and characteristics of layers with a photo, a diagram.

From Earth, the Sun looks like a smooth ball of fire, and before the discovery of sunspots by the comic ship Galileo, many astronomers thought it was perfectly shaped with no imperfections. Now we know that The sun is made up from several layers, like the Earth, each of which performs its own function. This structure of the Sun, like a massive oven, is the supplier of all the energy on Earth that is necessary for earthly life.

What elements does the sun consist of?

If you could take a star apart and compare the constituent elements, you would understand that the composition is 74% hydrogen and 24% helium. Also, the Sun consists of 1% oxygen, and the remaining 1% is such chemical elements of the periodic table as chromium, calcium, neon, carbon, magnesium, sulfur, silicon, nickel, iron. Astronomers believe that an element heavier than helium is a metal.

How did all these elements of the Sun come about? The Big Bang produced hydrogen and helium. At the beginning of the formation of the Universe, the first element, hydrogen, appeared from elementary particles. Due to the high temperature and pressure, the conditions in the Universe were like in the core of a star. Later, hydrogen was fused into helium as long as there was a high temperature in the universe necessary for the fusion reaction to take place. The existing proportions of hydrogen and helium, which are in the Universe now, were formed after the Big Bang and did not change.

The remaining elements of the Sun are created in other stars. The fusion of hydrogen into helium is constantly going on in the cores of stars. After producing all the oxygen in the core, they switch to nuclear fusion of heavier elements such as lithium, oxygen, helium. Many heavy metals, which are in the Sun, were formed in other stars at the end of their lives.

The formation of the heaviest elements, gold and uranium, occurred when stars many times the size of our Sun detonated. In a fraction of a second of the formation of a black hole, the elements collided at high speed and the heaviest elements were formed. The explosion scattered these elements throughout the universe, where they helped form new stars.

Our Sun has collected elements created by the Big Bang, elements from dying stars, and particles from new detonations of stars.

What are the layers of the Sun?

At first glance, the Sun is just a ball of helium and hydrogen, but a closer look reveals that it is made up of different layers. When moving towards the core, the temperature and pressure increase, as a result of which layers were created, since hydrogen and helium have different characteristics under different conditions.

solar core

Let's start our movement through the layers from the core to the outer layer of the composition of the Sun. In the inner layer of the Sun - the core, the temperature and pressure are very high, contributing to the flow of nuclear fusion. The sun creates helium atoms from hydrogen, as a result of this reaction, light and heat are formed, which reach up to. It is generally accepted that the temperature on the Sun is about 13,600,000 degrees Kelvin, and the density of the core is 150 times higher than the density of water.

Scientists and astronomers believe that the core of the Sun reaches about 20% of the length of the solar radius. And inside the nucleus, high temperature and pressure help break hydrogen atoms into protons, neutrons, and electrons. The sun converts them into helium atoms, despite their free-floating state.

Such a reaction is called exothermic. During the course of this reaction, a large amount of heat is released, equal to 389 x 10 31 J. per second.

Radiation zone of the Sun

This zone originates at the boundary of the core (20% of the solar radius), and reaches a length of up to 70% of the solar radius. Inside this zone is the solar matter, which is quite dense and hot in composition, so thermal radiation passes through it without losing heat.

Inside the solar core, a nuclear fusion reaction takes place - the creation of helium atoms as a result of the fusion of protons. As a result of this reaction, a large amount of gamma radiation occurs. In this process, photons of energy are emitted, then absorbed in the radiation zone and re-emitted by various particles.

The trajectory of a photon is called a "random walk". Instead of moving in a straight path to the surface of the Sun, the photon moves in a zigzag pattern. As a result, each photon needs approximately 200,000 years to overcome the radiation zone of the Sun. When passing from one particle to another particle, the photon loses energy. For the Earth, this is good, because we could only receive gamma radiation coming from the Sun. A photon that has fallen into space needs 8 minutes to travel to Earth.

A large number of stars have radiation zones, and their size directly depends on the scale of the star. The smaller the star, the smaller the zones will be, most of which will be occupied by the convective zone. The smallest stars may lack radiation zones, and the convective zone will reach the distance to the core. For the largest stars, the situation is the opposite, the radiation zone extends to the surface.

convective zone

The convective zone is outside the radiative zone, where the Sun's internal heat flows through columns of hot gas.

Almost all stars have such a zone. At our Sun, it extends from 70% of the radius of the Sun to the surface (photosphere). The gas in the depths of the star, at the very core, heats up and rises to the surface, like bubbles of wax in a lamp. Upon reaching the surface of the star, there is a loss of heat; when cooled, the gas sinks back to the center, for the renewal of thermal energy. As an example, you can bring a pot of boiling water over a fire.

The surface of the Sun is like loose soil. These irregularities are the columns of hot gas that carry heat to the surface of the Sun. Their width reaches 1000 km, and the dissipation time reaches 8-20 minutes.

Astronomers believe that stars of low mass, such as red dwarfs, have only a convective zone that extends to the core. They do not have a radiation zone, which cannot be said about the Sun.

Photosphere

The only layer of the Sun visible from the Earth is . Below this layer, the Sun becomes opaque, and astronomers use other methods to study the interior of our star. Surface temperatures as high as 6000 Kelvin glow yellow-white visible from Earth.

The Sun's atmosphere is located behind the photosphere. That part of the Sun that is visible during a solar eclipse is called.

The structure of the Sun in the diagram

NASA has specially developed for educational purposes a schematic representation of the structure and composition of the Sun, indicating the temperature for each layer:

• (Visible, IR and UV radiation) is visible radiation, infrared radiation and ultraviolet radiation. Visible radiation is the light that we see coming from the sun. Infrared radiation is the heat that we feel. Ultraviolet radiation is the radiation that gives us a tan. The sun produces these radiations simultaneously.
• (Photosphere 6000 K) - The photosphere is the upper layer of the Sun, its surface. A temperature of 6000 Kelvin is equal to 5700 degrees Celsius.
• Radio emissions - In addition to visible radiation, infrared radiation and ultraviolet radiation, the Sun sends out radio emissions, which astronomers have detected with a radio telescope. Depending on the number of sunspots, this emission increases and decreases.
• Coronal Hole (trans. Coronal hole) - These are places on the Sun where the corona has no greater density plasma, as a result it is darker and colder.
• 2100000 K (2100000 Kelvin) - The radiation zone of the Sun has this temperature.
• Convective zone/Turbulent convection (trans. Convective zone/Turbulent convection) - These are places on the Sun where the thermal energy of the core is transferred by convection. Plasma columns reach the surface, give off their heat, and rush down again to heat up again.
• Coronal loops (trans. Coronal loops) - loops consisting of plasma in the atmosphere of the Sun, moving along magnetic lines. They look like huge arches extending from the surface for tens of thousands of kilometers.
• Core (per. Core) is the solar heart, in which nuclear fusion takes place, using high temperature and pressure. All solar energy comes from the core.
• 14,500,000 K (per. 14,500,000 Kelvin) - The temperature of the solar core.
• Radiative Zone (trans. Radiation zone) - The layer of the Sun where energy is transferred using radiation. The photon overcomes the radiation zone beyond 200,000 and goes into outer space.
• Neutrinos (trans. Neutrino) are negligible mass particles emanating from the Sun as a result of a nuclear fusion reaction. Hundreds of thousands of neutrinos pass through the human body every second, but they do not bring us any harm, we do not feel them.
• Chromospheric Flare (trans. Chromospheric Flare) - The magnetic field of our star can twist, and then abruptly break in various forms. As a result of breaks in magnetic fields, powerful X-ray flares appear, emanating from the surface of the Sun.
• Magnetic Field Loop - The Sun's magnetic field is above the photosphere, and is visible as hot plasma moves along magnetic lines in the Sun's atmosphere.
• Spot - A sunspot (trans. Sunspots) - These are places on the surface of the Sun where magnetic fields pass through the surface of the Sun and the temperature is lower, often in a loop.
• Energetic particles (trans. Energetic particles) - They come from the surface of the Sun, as a result, the solar wind is created. In solar storms, their speed reaches the speed of light.
• X-rays (trans. X-rays) - rays invisible to the human eye, formed during flares on the Sun.
• Bright spots and short-lived magnetic regions (trans. Bright spots and short-lived magnetic regions) - Due to temperature differences, bright and dim spots appear on the surface of the Sun.

Since the 1930s, astrophysicists have had no doubt that of the nuclear reactions in light elements, the only one capable of sustaining the radiation of stars in the main sequence of the spectrum-luminosity diagram for a sufficiently long and energetic time is the formation of helium from hydrogen. Other reactions either last too short a time (of course, on a cosmic scale!), Or give too little energy output.

However, the path of direct union of four hydrogen nuclei into a helium nucleus turned out to be impossible: the reaction of the transformation of hydrogen into helium in the interiors of stars must go "roundabout ways".

The first way consists in the sequential connection of first two hydrogen atoms, then the addition of a third to them, and so on.

The second way is to convert hydrogen into helium with the "help" of nitrogen and especially carbon atoms.

Although the first way, it would seem, is simpler, for quite a long time he did not enjoy "due respect", and astrophysicists believed that the main reaction that feeds energy to stars is the second way - the "carbon cycle".

Four protons go to build a helium nucleus, which by themselves would never want to form an α-particle if carbon did not help them.

In the chain of these reactions, carbon plays the role of a necessary accomplice and, as it were, an organizer. IN chemical reactions also there are such accomplices, called catalysts.

During the construction of helium, energy is not only not spent, but, on the contrary, is released. Indeed, the chain of transformations was accompanied by the emission of three γ-quanta and two positrons, which also turned into γ-radiation. The balance is: 10 -5 (4·1.00758-4.00390) = 0.02642·10 -5 atomic mass units.

The energy associated with this mass is released in the bowels of the star, seeping slowly to the surface and then radiating into the world space. The helium factory works continuously in the stars until the raw materials, i.e., hydrogen, run out. What happens next, we will tell further.

Carbon as a catalyst will last indefinitely.

At temperatures of the order of 20 million degrees, the action of the reactions of the carbon cycle is proportional to the 17th degree of temperature! At some distance from the center of the star, where the temperature is only 10% lower, energy production drops by a factor of 5, and where it is one and a half times lower, it drops by 800 times! Therefore, already not far from the central, most incandescent region, the formation of helium due to hydrogen does not occur. The rest of the hydrogen will turn into helium after the mixing of gases will bring it into the territory of the "factory" - to the center of the star.

In the early fifties, it became clear that at a temperature of 20 million degrees, and even more so at lower temperatures, the proton-proton reaction is even more effective, also leading to the loss of hydrogen and the formation of helium. Most likely, it proceeds in such a chain of transformations.

Two protons, colliding, emit a positron and a quantum of light, turning into a heavy hydrogen isotope with a relative atomic mass of 2. The latter, after merging with another proton, turns into an atom of a light hydrogen isotope with a relative atomic mass of 2. The latter, after merging with another proton, turns into a light atom isotope of helium with a relative atomic mass of 3, while emitting an excess of mass in the form of radiation. If enough such light helium atoms have accumulated, their nuclei collide to form a normal helium atom with a relative atomic mass of 4 and two protons with an energy quantum in addition. So, in this process, three protons were lost, and two appeared - one proton decreased, but energy was emitted three times.

Apparently, the Sun and cooler main-sequence stars of the luminosity-spectrum diagram draw their energy from this source.

When all the hydrogen has been converted to helium, the star can still exist by converting helium into heavier elements. For example, the processes are:

4 2 He + 4 2 He → 8 4 Be + radiation,

4 2 He + 8 4 Be → 12 6 C + radiation.

In this case, one helium particle gives an energy output that is 8 times less than it gives the same particle in the carbon cycle described above.

Recently, physicists have found that in some stars the physical conditions allow the occurrence of even heavier elements, such as iron, and they calculate the proportion of the resulting elements in accordance with the abundance of elements that we find in nature.

Giant stars have an average energy output per unit mass much greater than that of the Sun. However, there is still no generally accepted point of view on the sources of energy in red giant stars. The sources of energy in them and their structure are not yet clear to us, but, apparently, they will soon become known. According to V.V. Sobolev, red giants can have the same structure as hot giants and have the same energy sources. But they are surrounded by vast rarefied and cold atmospheres, which give them the appearance of "cold giants".

The nuclei of some heavy atoms can be formed in the interiors of stars due to the combination of lighter atoms, and under certain conditions, even in their atmospheres.

What is the source of solar energy? What is the nature of the processes during which a huge amount of energy is produced? How long will the sun continue to shine?

The first attempts to answer these questions were made by astronomers in the middle of the 19th century, after the physicists formulated the law of conservation of energy.

Robert Mayer suggested that the Sun shines due to the constant bombardment of the surface by meteorites and meteor particles. This hypothesis was rejected, since a simple calculation shows that in order to maintain the luminosity of the Sun at the current level, it is necessary that 2 * 1015 kg of meteoric matter fall on it every second. For a year it will be 6 * 1022 kg, and during the existence of the Sun, for 5 billion years - 3 * 1032 kg. The mass of the Sun is M = 2 * 1030 kg, therefore, in five billion years, matter 150 times more than the mass of the Sun should have fallen on the Sun.

The second hypothesis was also put forward by Helmholtz and Kelvin in the middle of the 19th century. They suggested that the Sun radiates by contracting 60–70 meters annually. The reason for the contraction is the mutual attraction of the particles of the Sun, which is why this hypothesis is called contraction. If we make a calculation according to this hypothesis, then the age of the Sun will be no more than 20 million years, which contradicts modern data obtained from the analysis of the radioactive decay of elements in geological samples of the earth's soil and the Moon's soil.

The third hypothesis about the possible sources of solar energy was put forward by James Jeans at the beginning of the 20th century. He suggested that the depths of the Sun contain heavy radioactive elements that spontaneously decay, while energy is emitted. For example, the transformation of uranium into thorium and then into lead is accompanied by the release of energy. Subsequent analysis of this hypothesis also showed its failure; a star composed of only uranium would not release enough energy to provide the observed luminosity of the Sun. In addition, there are stars that are many times more luminous than our star. It is unlikely that those stars would also contain more radioactive material.

The most probable hypothesis turned out to be the hypothesis of the synthesis of elements as a result of nuclear reactions in the interiors of stars.

In 1935, Hans Bethe hypothesized that the thermonuclear reaction of converting hydrogen into helium could be the source of solar energy. It is for this that Bethe received Nobel Prize in 1967.

The chemical composition of the Sun is about the same as that of most other stars. Approximately 75% is hydrogen, 25% is helium, and less than 1% is all other chemical elements (mainly carbon, oxygen, nitrogen, etc.). Immediately after the birth of the Universe, there were no "heavy" elements at all. All of them, i.e. elements heavier than helium, and even many alpha particles, were formed during the "burning" of hydrogen in stars during thermonuclear fusion. The characteristic lifetime of a star like the Sun is ten billion years.

The main source of energy - the proton-proton cycle - is a very slow reaction (characteristic time 7.9 * 109 years), as it is due to weak interaction. Its essence lies in the fact that from four protons a helium nucleus is obtained. In this case, a pair of positrons and a pair of neutrinos are released, as well as 26.7 MeV of energy. The number of neutrinos emitted by the Sun per second is determined only by the luminosity of the Sun. Since when 26.7 MeV is released, 2 neutrinos are born, the neutrino emission rate is: 1.8 * 1038 neutrinos / s.

A direct test of this theory is the observation of solar neutrinos. High-energy neutrinos (boron) are recorded in chlorine-argon experiments (Davis experiments) and consistently show a lack of neutrinos compared to the theoretical value for the standard solar model. Low-energy neutrinos that arise directly in the pp reaction are recorded in gallium-germanium experiments (GALLEX at Gran Sasso (Italy-Germany) and SAGE at Baksan (Russia-USA)); they are also "missing".

According to some assumptions, if neutrinos have a non-zero rest mass, oscillations (transformations) of various types of neutrinos are possible (the Mikheev-Smirnov-Wolfenstein effect) (there are three types of neutrinos: electron, muon and tauon neutrinos). Because other neutrinos have much smaller interaction cross sections with matter than electrons, the observed deficit can be explained without changing the standard model of the Sun, built on the basis of the entire set of astronomical data.

Every second, the Sun recycles about 600 million tons of hydrogen. Stocks of nuclear fuel will last another five billion years, after which it will gradually turn into a white dwarf.

The central parts of the Sun will shrink, heating up, and the heat transferred to the outer shell will lead to its expansion to sizes monstrous compared to modern ones: the Sun will expand so much that it will absorb Mercury, Venus and will spend "fuel" a hundred times faster, than at present. This will increase the size of the Sun; our star will become a red giant, the size of which is comparable to the distance from the Earth to the Sun! Life on Earth will disappear or find a home on the outer planets.

Of course, we will be notified in advance of such an event, since the transition to a new stage will take approximately 100-200 million years. When the temperature of the central part of the Sun reaches 100,000,000 K, helium will also begin to burn, turning into heavy elements, and the Sun will enter a stage of complex cycles of contraction and expansion. At the last stage, our star will lose its outer shell, the central core will have an incredibly large density and size, like that of the Earth. A few more billion years will pass, and the Sun will cool down, turning into a white dwarf.