Thermonuclear fusion. Cold fusion: experiments create energy that shouldn't exist

Controlled thermonuclear fusion is an interesting physical process that (still in theory) can save the world from energy dependence on fossil fuel sources. The process is based on the synthesis of atomic nuclei from lighter ones to heavier ones with the release of energy. Unlike another use of the atom - releasing energy from it in nuclear reactors through the process of decay - fusion on paper will leave virtually no radioactive byproducts. Particular hopes are placed on the ITER reactor, the creation of which was spent on an insane amount of money. Skeptics, however, rely on the developments of private corporations.

In 2018, scientists reported the stark news that despite concerns about global warming, coal generated 38% of the world's electricity in 2017—the same amount as when climate warnings first began 20 years ago. Worse yet Greenhouse gas emissions rose 2.7% last year, the largest increase in seven years. This stagnation has led even politicians and environmentalists to start thinking that we need more nuclear energy.

• Translation

This field is now called low-energy nuclear reactions, and it may be where real results are achieved - or it may turn out to be stubborn junk science

Dr. Martin Fleischman (right), an electrochemist, and Stanley Pons, chairman of the chemistry department at the University of Utah, answer questions from the Science and Technology Committee about their controversial work in cold fusion, April 26, 1989.

Howard J. Wilk - chemist, specialist in synthetic organics, already for a long time does not work in his specialty and lives in Philadelphia. Like many other pharmaceutical researchers, he fell victim to the drug industry's R&D cuts in recent years and now takes part-time jobs unrelated to science. With time on his hands, Wilk tracks the progress of New Jersey company Brilliant Light Power (BLP).

This is one of those companies that is developing processes that can be generally referred to as new energy extraction technologies. The movement is largely a resurrection of cold fusion, a short-lived 1980s phenomenon involving producing nuclear fusion in a simple benchtop electrolytic device that scientists quickly dismissed.

In 1991, BLP founder, Randall L. Mills, announced at a press conference in Lancaster, Pennsylvania, the development of a theory in which an electron in hydrogen could transition from a normal, ground energy state to previously unknown, more stable, lower energy states. , with the release of huge amounts of energy. Mills called this strange new type compressed hydrogen, " ", and has since been working on developing a commercial device that harvests this energy.

Wilk studied Mills' theory, read papers and patents, and did his own calculations for hydrinos. Wilk even attended a demonstration at BLP grounds in Cranbury, New Jersey, where he discussed hydrino with Mills. After this, Wilk still can't decide whether Mills is a unrealistic genius, a raving scientist, or something in between.

The story begins in 1989, when electrochemists Martin Fleischmann and Stanley Pons made the astonishing announcement at a University of Utah press conference that they had tamed the energy of nuclear fusion in an electrolytic cell.

When the researchers applied an electric current to the cell, they believed the deuterium atoms from heavy water, which penetrated the palladium cathode, entered into a fusion reaction and generated helium atoms. The excess energy of the process was converted into heat. Fleischmann and Pons argued that this process could not be the result of any known chemical reaction, and added the term " cold fusion».

After many months of investigation into their mysterious observations, however, the scientific community agreed that the effect was unstable or non-existent and that errors were made in the experiment. The research was scrapped, and cold fusion became synonymous with junk science.

Cold fusion and hydrino production are the holy grail for producing endless, cheap, and clean energy. Cold fusion has disappointed scientists. They wanted to believe in him, but their collective mind decided that it was a mistake. Part of the problem was the lack of a generally accepted theory to explain the proposed phenomenon - as physicists say, you cannot trust an experiment until it is confirmed by a theory.

Mills has his own theory, but many scientists don't believe it and consider hydrinos unlikely. The community rejected cold fusion and ignored Mills and his work. Mills did the same, trying not to fall into the shadow of cold fusion.

Meanwhile, the field of cold fusion changed its name to low-energy nuclear reactions (LENR) and continues to exist. Some scientists continue to try to explain the Fleischmann-Pons effect. Others have rejected nuclear fusion but are exploring other possible processes that could explain the excess heat. Like Mills, they were attracted by the potential for commercial applications. They are mainly interested in energy production for industrial needs, households and transport.

The small number of companies created to try to bring new energy technologies to market have business models similar to those of any technology startup: identify new technology, try to patent the idea, generate investor interest, obtain funding, build prototypes, conduct demonstrations, announce dates for workers devices for sale. But in the new energy world, missing deadlines is the norm. No one has yet taken the final step of demonstrating a working device.

New theory

Mills grew up on a farm in Pennsylvania, received a degree in chemistry from Franklin and Marshall College, a medical degree from Harvard University, and studied electrical engineering at the Massachusetts Institute of Technology. As a student, he began developing a theory he called the "Grand Unified Theory of Classical Physics", which he said was based on classical physics and proposed a new model of atoms and molecules that departed from the foundations of quantum physics.

It is generally accepted that a single electron of hydrogen darts around its nucleus, located in the most suitable orbit of the ground state. It is simply impossible to move a hydrogen electron closer to the nucleus. But Mills says it's possible.

Now a researcher at Airbus Defense & Space, he says he has not monitored Mills' activities since 2007 because the experiments did not show clear signs of excess energy. "I doubt that any of the later experiments were scientifically selected," Rathke said.

“I think it is generally accepted that Dr. Mills's theory as the basis for his claims is controversial and not predictive,” Rathke continues. – One might ask, “Could we have so fortunately stumbled upon an energy source that simply works by following the wrong theoretical approach?" ».

In the 1990s, several researchers, including a team from Research Center Lewis, independently reported replicating Mills' approach and generating excess heat. The NASA team wrote in the report that “the results are far from convincing” and did not say anything about hydrino.

Researchers have proposed possible electrochemical processes to explain the heat, including irregularities in the electrochemical cell, unknown exothermic chemical reactions, and recombination of separated hydrogen and oxygen atoms in water. The same arguments were made by critics of the Fleischmann-Pons experiments. But the NASA team clarified that researchers shouldn't discount the phenomenon, just in case Mills was onto something.

Mills speaks very quickly and can go on and on about technical details. In addition to predicting hydrinos, Mills claims that his theory can perfectly predict the location of any electron in a molecule using special molecular modeling software, and even in complex molecules such as DNA. Using standard quantum theory Scientists have a hard time predicting the exact behavior of anything more complex than a hydrogen atom. Mills also claims that his theory explains the phenomenon of the expansion of the Universe with acceleration, which cosmologists have not yet fully understood.

In addition, Mills says that hydrinos are created by the combustion of hydrogen in stars such as our Sun, and that they can be detected in the spectrum of starlight. Hydrogen is considered the most abundant element in the universe, but Mills argues that hydrino is dark matter, which cannot be found in the universe. Astrophysicists are surprised by such suggestions: "I've never heard of hydrinos," says Edward W. (Rocky) Kolb of the University of Chicago, an expert on the dark universe.

Mills reported successful isolation and characterization of hydrinos using standard spectroscopic techniques such as infrared, Raman, and nuclear magnetic resonance spectroscopy. In addition, he said, hydrinos can enter into reactions that lead to the emergence of new types of materials with “ amazing properties" This includes conductors, which Mills says will revolutionize the world of electronic devices and batteries.

And although his statements contradict public opinion, Mills' ideas do not seem so exotic compared to other unusual components of the Universe. For example, muonium is a known short-lived exotic entity consisting of an antimuon (a positively charged particle similar to an electron) and an electron. Chemically, muonium behaves like an isotope of hydrogen, but is nine times lighter.

SunCell, hydrin fuel cell

Regardless of where hydrinos fall on the credibility scale, Mills said a decade ago that BLP had moved beyond scientific confirmation and was only interested in the commercial side of things. Over the years, BLP has raised more than $110 million in investments.

BLP's approach to creating hydrinos has manifested itself in a variety of ways. In early prototypes, Mills and his team used tungsten or nickel electrodes with an electrolytic solution of lithium or potassium. The supplied current split the water into hydrogen and oxygen, and when the right conditions lithium or potassium played the role of a catalyst to absorb energy and collapse the electron orbit of hydrogen. The energy created by the transition from the ground atomic state to a lower energy state was released in the form of bright, high-temperature plasma. The associated heat was then used to create steam and power an electric generator.

BLP is currently testing a device called SunCell, which feeds hydrogen (from water) and an oxide catalyst into a spherical carbon reactor with two streams of molten silver. An electrical current applied to the silver triggers a plasma reaction to form hydrinos. The reactor's energy is captured by carbon, which acts as a "black body radiator." When it heats up to thousands of degrees, it emits energy in the form of visible light, which is captured by photovoltaic cells that convert the light into electricity.

Regarding commercial developments Mills sometimes comes across as paranoid and at other times like a practical businessman. He registered trademark"Hydrino". And because its patents claim the invention of hydrino, BLP claims intellectual property for hydrino research. Because of this, the BLP prohibits other experimenters from conducting even basic research on hydrinos that could confirm or disprove their existence without first signing an intellectual property agreement. "We invite researchers, we want others to do this," Mills says. “But we need to protect our technology.”

Instead, Mills appointed authorized validators who claim to be able to confirm the functionality of BLP inventions. One of them is Bucknell University electrical engineer Professor Peter M. Jansson, who is being paid to evaluate BLP technology through his consulting company, Integrated Systems. Jenson claims that compensation for his time “does not in any way affect my conclusions as independent researcher scientific discoveries" He adds that he has "disproved most of the findings" he has studied.

“BLP scientists are doing real science, and so far I have not found any errors in their methods and approaches,” says Jenson. – Over the years, I have seen many devices in BLP that are clearly capable of producing excess energy in meaningful quantities. I think it will take some time for the scientific community to accept and digest the possibility of the existence of low-energy states of hydrogen. In my opinion, Dr. Mills' work is undeniable." Jenson adds that BLP faces challenges in commercializing the technology, but the obstacles are business rather than scientific.

In the meantime, BLP has held several demonstrations of its new prototypes for investors since 2014, and published videos on its website. But these events do not provide clear evidence that SunCell actually works.

In July, following one of its demonstrations, the company announced that the estimated cost of energy from SunCell is so low—1% to 10% of any other known form of energy—that the company is “going to provide self-contained, customized power supplies for virtually all stationary and mobile applications, not tied to the power grid or fuel energy sources." In other words, the company plans to build and lease SunCells or other devices to consumers, charging a daily fee, allowing them to go off the grid and stop buying gasoline or solar power while spending a fraction of the money.

"This is the end of the era of fire, engine internal combustion And centralized systems energy supply,” says Mills. “Our technology will make all other forms of energy technology obsolete. Climate change problems will be solved." He adds that it appears BLP could begin production, to begin with MW plants, by the end of 2017.

What's in a name?

Despite the uncertainty surrounding Mills and the BLP, their story is only part of the larger new energy saga. As the dust settled from Fleischmann-Pons's initial announcement, two researchers began studying what was right and what was wrong. They were joined by dozens of co-authors and independent researchers.

Many of these scientists and engineers, often self-funded, were interested less in commercial opportunities than in science: electrochemistry, metallurgy, calorimetry, mass spectrometry, and nuclear diagnostics. They continued to run experiments that produced excess heat, defined as the amount of energy produced by a system relative to the energy required to operate it. In some cases, nuclear anomalies were reported, such as the appearance of neutrinos, alpha particles (helium nuclei), isotopes of atoms and transmutations of some elements to others.

But ultimately, most researchers are looking for an explanation for what's happening, and would be happy if even a modest amount of heat were useful.

"LENRs are in an experimental phase and are not yet understood theoretically," says David J. Nagel, professor of electrical engineering and computer science at the University. George Washington, and former manager on research at the Marine Research Laboratory. “Some results are simply inexplicable. Call it cold fusion, low-energy nuclear reactions, or whatever - there are plenty of names - we still don't know anything about it. But there is no doubt that nuclear reactions can be started using chemical energy.”

Nagel prefers to call the LENR phenomenon “lattice nuclear reactions,” since the phenomenon occurs in the crystal lattices of the electrode. An initial offshoot of this field focuses on introducing deuterium into a palladium electrode by applying high energy, Nagel explains. Researchers have reported that such electrochemical systems can produce up to 25 times more energy than they consume.

The other main offshoot of the field uses combinations of nickel and hydrogen, which produces up to 400 times more energy than it consumes. Nagel likes to compare these LENR technologies to the experimental international fusion reactor, based on well-known physics - the fusion of deuterium and tritium - which is being built in the south of France. The 20-year project costs $20 billion and aims to produce 10 times the energy consumed.

Nagel says the field of LENR is growing everywhere, and the main obstacles are a lack of funding and inconsistent results. For example, some researchers report that a certain threshold must be reached to trigger the reaction. She may demand minimum quantity deuterium or hydrogen to trigger, or the electrodes need to be prepared with crystallographic orientation and surface morphology. The last requirement is common for heterogeneous catalysts used in gasoline purification and petrochemical production.

Nagel acknowledges that the commercial side of LENR also has problems. The prototypes being developed are, he says, “pretty crude,” and there has yet to be a company that has demonstrated a working prototype or made money from it.

E-Cat from Russia

One of the most striking attempts to put LENR on a commercial basis was made by an engineer from Leonardo Corp, located in Miami. In 2011, Rossi and his colleagues announced at a press conference in Italy the construction of a benchtop "Energy Catalyst" reactor, or E-Cat, that produces excess energy in a process using nickel as a catalyst. To substantiate the invention, Rossi demonstrated the E-Cat to potential investors and the media, and commissioned independent tests.

Rossi claims that his E-Cat undergoes a self-sustaining process in which an incoming electrical current triggers the synthesis of hydrogen and lithium in the presence of a powder mixture of nickel, lithium and lithium aluminum hydride, resulting in an isotope of beryllium. Short-lived beryllium decays into two alpha particles, and the excess energy is released as heat. Some of the nickel turns into copper. Rossi talks about the absence of both waste and radiation outside the device.

Rossi's announcement gave scientists the same unpleasant feeling as cold fusion. Rossi is mistrusted by many people due to his controversial past. In Italy he was accused of fraud due to his previous business dealings. Rossi says the allegations are in the past and doesn't want to discuss them. He also once had a contract to create thermal systems for the US military, but the devices he supplied did not work to specifications.

In 2012, Rossi announced the creation of a 1 MW system suitable for heating large buildings. He also assumed that by 2013 he would already have a factory producing a million 10 kW, laptop-sized units annually, designed for home use. But neither the factory nor these devices ever happened.

In 2014, Rossi licensed the technology to Industrial Heat, Cherokee's public investment firm that buys real estate and clears old industrial sites for new development. In 2015 CEO Cherokee, Tom Darden, a lawyer and environmental scientist by training, called Industrial Heat "a source of funding for the inventors of LENR."

Darden says Cherokee launched Industrial Heat because the investment firm believes the LENR technology is worthy of research. “We were willing to be wrong, we were willing to invest time and resources to see if this area could be useful in our mission to prevent pollution [ environment],” he says.

Meanwhile, Industrial Heat and Leonardo had a fight and are now suing each other over violations of the agreement. Rossi would receive $100 million if a one-year test of his 1 MW system was successful. Rossi says the test is complete, but Industrial Heat doesn't think so and fears the device isn't working.

Nagel says E-Cat has brought enthusiasm and hope to the NLNR field. He argued in 2012 that he believed Rossi was not a fraud, "but I don't like some of his approaches to testing." Nagel believed that Rossi should have acted more carefully and transparently. But at that time, Nagel himself believed that devices based on the LENR principle would appear on sale by 2013.

Rossi continues his research and has announced the development of other prototypes. But he doesn't say much about his work. He says 1 MW units are already in production and he has received the “necessary certifications” to sell them. Home devices, he said, are still awaiting certification.

Nagel says that after the elation surrounding Rossi's announcements subsided, the status quo has returned to NLNR. The availability of commercial LENR generators has been delayed by several years. And even if the device survives reproducibility issues and proves useful, its developers face an uphill battle with regulators and user acceptance.

But he remains optimistic. “LENR may become commercially available before it is fully understood, just like X-rays were,” he says. He has already equipped a laboratory at the University. George Washington for new experiments with nickel and hydrogen.

Scientific heritage

Many researchers who continue to work on LENR are already accomplished retired scientists. This is not easy for them, because for years their work has been returned unreviewed from mainstream journals, and their proposals to present at scientific conferences have been rejected. They are increasingly worried about the status of this area of ​​research as their time runs out. They either want to record their heritage in scientific history NEYAR, or at least take comfort in the fact that their instincts did not let them down.

“It was very unfortunate when cold fusion was first published in 1989 as new source fusion energy, not just some new scientific curiosity,” says electrochemist Melvin Miles. “Perhaps the research could proceed as usual, with more careful and precise study.”

A former researcher at the China Lake Air and Maritime Research Center, Miles sometimes worked with Fleischman, who died in 2012. Miles believes Fleischman and Pons were right. But to this day he does not know how to make a commercial energy source for a system of palladium and deuterium, despite many experiments in which excess heat was obtained that correlated with the production of helium.

“Why would anyone continue to research or be interested in a topic that was declared a mistake 27 years ago? – asks Miles. – I am convinced that cold fusion will someday be recognized as another important discovery, which has been accepted for a long time, and a theoretical platform will appear that explains the results of the experiments.”

Nuclear physicist Ludwik Kowalski, professor emeritus from Montclair state university agrees that cold fusion was the victim of a bad start. "I'm old enough to remember the effect the first announcement had on the scientific community and the public," Kowalski says. At times he collaborated with NLNR researchers, “but my three attempts to confirm the sensational claims were unsuccessful.”

Kowalski believes that the initial disgrace earned by the research resulted in bigger problem unsuitable for the scientific method. Whether the LENR researchers are fair or not, Kowalski still believes it is worth getting to the bottom of a clear yes or no verdict. But it won't be found as long as cold fusion researchers are considered "eccentric pseudoscientists," Kowalski says. “Progress is impossible and no one benefits when the results of honest research are not published and independently verified by other laboratories.”

Time will show

Even if Kowalski gets a definite answer to his question and the statements of the LENR researchers are confirmed, the road to commercialization of the technology will be full of obstacles. Many startups, even with reliable technology, fail for reasons unrelated to science: capitalization, liquidity flow, cost, production, insurance, uncompetitive prices, etc.

Take Sun Catalytix for example. The company emerged from MIT with the backing of solid science, but fell victim to commercial attacks before it hit the market. It was created to commercialize artificial photosynthesis, developed by chemist Daniel G. Nocera, now at Harvard, to efficiently convert water into hydrogen fuel using sunlight and an inexpensive catalyst.

Nocera dreamed that the hydrogen produced in this way could power simple fuel cells and power homes and villages in underserved regions of the world without access to the grid, allowing them to enjoy modern conveniences that improve their standard of living. But the development took much more money and time than it seemed at first. After four years, Sun Catalytix gave up trying to commercialize the technology, started making flow batteries, and then in 2014 it was bought by Lockheed Martin.

It is unknown whether the same obstacles hinder the development of companies involved in LENR. For example, Wilk, an organic chemist who has been following Mills' progress, is concerned about whether attempts to commercialize BLP are based on something real. He just needs to know if hydrino exists.

In 2014, Wilk asked Mills if he had isolated hydrino, and although Mills had already written in papers and patents that he had succeeded, he replied that such a thing had not yet been done and that it would be “a very big task.” But Wilk thinks differently. If the process creates liters of hydrine gas, it should be obvious. “Show us the hydrino!” Wilk demands.

Wilk says that Mills' world, and with it the world of other people involved in LENR, reminds him of one of Zeno's paradoxes, which speaks of the illusory nature of movement. “Every year they get halfway to commercialization, but will they ever get there?” Wilk came up with four explanations for the BLP: Mills' calculations are correct; This is a fraud; This is bad science; it is a pathological science, as Nobel laureate in physics Irving Langmuir called it.

Langmuir invented the term more than 50 years ago to describe the psychological process in which a scientist subconsciously withdraws from scientific method and becomes so immersed in his occupation that he develops the inability to look at things objectively and see what is real and what is not. Pathological science is “the science of things not being what they seem,” said Langmuir. In some cases, it develops in areas such as cold fusion/LENR, and does not give up, despite the fact that it is recognized as false by the majority of scientists.

"I hope they're right," Wilk says of Mills and the BLP. "Indeed. I don’t want to refute them, I’m just looking for the truth.” But if "pigs could fly," as Wilkes says, he would accept their data, theory, and other predictions that follow from it. But he was never a believer. “I think if hydrinos existed, they would have been discovered in other laboratories or in nature many years ago.”

All discussions of cold fusion and LENR end exactly like this: they always come to the conclusion that no one has brought a working device to the market, and none of the prototypes can be commercialized in the near future. So time will be the final judge.

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thermonuclear fusion, the reaction of the fusion of light atomic nuclei into heavier nuclei, occurring at ultra-high temperatures and accompanied by the release of huge amounts of energy. Nuclear fusion is a reaction inverse to atomic fission: in the latter, energy is released due to the splitting of heavy nuclei into lighter ones. see also NUCLEUS FISSION; NUCLEAR POWER.

According to modern astrophysical concepts, the main source of energy of the Sun and other stars is thermonuclear fusion occurring in their depths. Under terrestrial conditions, it is carried out during an explosion hydrogen bomb. Thermonuclear fusion is accompanied by a colossal energy release per unit mass of reacting substances (about 10 million times greater than in chemical reactions). Therefore, it is of great interest to master this process and, based on it, create a cheap and environmentally friendly pure source energy. However, despite the fact that research-driven thermonuclear fusion(TCF) is occupied by large scientific and technical teams in many developed countries, many complex problems still need to be solved before the industrial production of thermonuclear energy becomes a reality.

Modern nuclear power plants using the fission process only partially satisfy the world's electricity needs. The fuel for them is the natural radioactive elements uranium and thorium, the abundance and reserves of which in nature are very limited; therefore, many countries face the problem of importing them. The main component of thermonuclear fuel is the hydrogen isotope deuterium, which is found in sea water. Its reserves are publicly available and very large (the world's oceans cover ~ 71% of the Earth's surface area, and deuterium accounts for about 0.016% total number hydrogen atoms that make up water). In addition to the availability of fuel, thermonuclear energy sources have the following important advantages over nuclear power plants: 1) the UTS reactor contains much less radioactive materials than atomic reactor fission, and therefore the consequences of an accidental release of radioactive products are less dangerous; 2) at thermo nuclear reactions less long-lived radioactive waste is generated; 3) TCB allows direct receipt electricity.

Artsimovich L.A. Controlled thermonuclear reactions. M., 1963
Thermal and nuclear power stations (book 1, section 6; book 3, section 8). M., 1989

Find "NUCLEAR fusion" on

Shikanov A.S. // Soros educational journal, No. 8, 1997, pp: 86-91

We will look at the physical principles of laser thermonuclear fusion - a rapidly developing scientific field, which is based on two outstanding discoveries of the 20th century: thermonuclear reactions and lasers.

Thermonuclear reactions occur during the fusion (fusion) of nuclei of light elements. In this case, along with the formation of heavier elements, excess energy is released in the form of kinetic energy of the final reaction products and gamma radiation. The large energy release during thermonuclear reactions attracts the attention of scientists because of the possibility of their practical application in terrestrial conditions. Thus, thermonuclear reactions on a large scale were carried out in a hydrogen (or thermonuclear) bomb.

The possibility of utilizing the energy released during thermonuclear reactions to solve the energy problem seems extremely attractive. The fact is that the fuel for this method of generating energy is the hydrogen isotope deuterium (D), the reserves of which in the World Ocean are practically inexhaustible.

THERMONUCLEAR REACTIONS AND CONTROLLED fusion

A thermonuclear reaction is the process of fusion (or fusion) of light nuclei into heavier ones. Since this involves the formation of strongly bound nuclei from looser ones, the process is accompanied by the release of binding energy. The easiest way to merge is the isotopes of hydrogen - deuterium D and tritium T. The deuterium nucleus - the deuteron contains one proton and one neutron. Deuterium is contained in water in a ratio of one part to 6500 parts hydrogen. The tritium nucleus, the triton, consists of a proton and two neutrons. Tritium is unstable (half-life 12.4 years), but can be produced from nuclear reactions.

The fusion of deuterium and tritium nuclei produces helium He with an atomic mass of four and a neutron n. As a result of the reaction, an energy of 17.6 MeV is released.

The fusion of deuterium nuclei occurs through two channels with approximately the same probability: in the first, tritium and proton p are formed and energy equal to 4 MeV is released; in the second channel there is helium with atomic mass 3 and a neutron, and the released energy is 3.25 MeV. These reactions are represented as formulas

D + T = 4He + n + 17.6 MeV,

D + D = T + p + 4.0 MeV,

D + D = 3He + n + 3.25 MeV.

Before the fusion process, the nuclei of deuterium and tritium have an energy of about 10 keV; the energy of the reaction products reaches values ​​on the order of units and tens of megaelectronvolts. It should also be noted that the cross section of the D + T reaction and its rate of occurrence are much higher (hundreds of times) than for the D + D reaction. Consequently, for the D + T reaction it is much easier to achieve conditions when the released thermonuclear energy exceeds the costs of organizing the processes mergers.

Synthesis reactions involving other nuclei of elements (for example, lithium, boron, etc.) are also possible. However, the reaction cross sections and their rates for these elements are significantly smaller than for hydrogen isotopes, and reach noticeable values ​​only for temperatures of the order of 100 keV. Achieving such temperatures in thermonuclear installations is currently completely unrealistic, therefore only fusion reactions of hydrogen isotopes can have practical use soon.

How can a thermonuclear reaction be carried out? The problem is that the fusion of nuclei is prevented by electrical repulsion forces. In accordance with Coulomb's law, the electric repulsion force grows in inverse proportion to the square of the distance between interacting nuclei F ~ 1/ r 2. Therefore, for the synthesis of nuclei, the formation of new elements and the release of excess energy, it is necessary to overcome the Coulomb barrier, that is, to do work against the repulsion forces, imparting energy to the nuclei the necessary energy.

There are two possibilities. One of them involves the collision of two beams of light atoms accelerated towards each other. It turned out, however, that this way is ineffective. The fact is that the probability of fusion of nuclei in accelerated beams is extremely low due to the low density of nuclei and the negligible time of their interaction, although creating beams of the required energy in existing accelerators is not a problem.

Another way, which modern researchers have settled on, is heating the substance to high temperatures (about 100 million degrees). The higher the temperature, the higher the average kinetic energy of particles and the greater their number can overcome the Coulomb barrier.

To quantify the efficiency of thermonuclear reactions, an energy gain factor Q is introduced equal to

where Eout is the energy released as a result of fusion reactions, Eust is the energy used to heat the plasma to thermonuclear temperatures.

In order for the energy released as a result of the reaction to be equal to the energy costs for heating the plasma to temperatures of the order of 10 keV, it is necessary to fulfill the so-called Lawson criterion:

(Nt) $ 1014 s/cm3 for D-T reaction,

(Nt) $ 1015 s/cm3 for D-D reaction.

Here N is the density of the deuterium-tritium mixture (the number of particles per cubic centimeter), t is the time for the fusion reactions to occur effectively.

To date, two largely independent approaches to solving the problem of controlled thermonuclear fusion have emerged. The first of them is based on the possibility of confining and thermally insulating high-temperature plasma of relatively low density (N © 1014-1015 cm-3) by a magnetic field of a special configuration for a relatively long time (t © 1-10 s). Such systems include Tokamak (short for “toroidal chamber with magnetic coils”), proposed in the 50s in the USSR.

The other way is impulse. With the pulsed approach, it is necessary to quickly heat and compress small portions of matter to such temperatures and densities at which thermonuclear reactions would have time to proceed effectively during the existence of an unconfined or, as they say, inertially confined plasma. Estimates show that in order to compress a substance to densities of 100-1000 g/cm3 and heat it to a temperature T © 5-10 keV, it is necessary to create a pressure on the surface of a spherical target P © 5 » 109 atm, that is, a source is needed that would allow energy with a power density of q © 1015 W/cm2 to be supplied to the target surface.

PHYSICAL PRINCIPLES OF LASER THERMONUCLEAR FUSION

For the first time the idea of ​​using powerful laser radiation for heating dense plasma to thermonuclear temperatures was proposed by N.G. Basov and O.N. Krokhin in the early 60s. To date, an independent direction of thermonuclear research has formed - laser thermonuclear fusion (LTF).

Let us dwell briefly on what basic physical principles are embedded in the concept of achieving high degrees compression of substances and obtaining large energy gains using laser microexplosions. We will base our discussion on the example of the so-called direct compression mode. In this mode, a microsphere (Fig. 1), filled with thermonuclear fuel, is “uniformly” irradiated from all sides by a multichannel laser. As a result of the interaction of heating radiation with the target surface, a hot plasma with a temperature of several kiloelectronvolts (the so-called plasma corona) is formed, flying towards the laser beam with characteristic speeds of 107-108 cm/s.

Without being able to dwell in more detail on the absorption processes in the plasma corona, we note that in modern model experiments at laser radiation energies of 10-100 kJ for targets comparable in size to targets for large gains, it is possible to achieve high (© 90%) absorption coefficients of heating radiation.

As we have already seen, light radiation cannot penetrate dense layers of the target (the density of a solid is © 1023 cm-3). Due to thermal conductivity, the energy absorbed in a plasma with an electron density less than ncr is transferred to denser layers, where ablation of the target substance occurs. The remaining unevaporated layers of the target, under the influence of thermal and reactive pressure, are accelerated towards the center, compressing and heating the fuel contained in it (Fig. 2). As a result, the energy of laser radiation is converted at the stage under consideration into the kinetic energy of matter flying towards the center and into the energy of the expanding corona. It's obvious that useful energy concentrated in movement towards the center. The efficiency of the contribution of light energy to the target is characterized by the ratio of the specified energy to the total radiation energy - the so-called hydrodynamic efficiency (efficiency). Achieving a sufficiently high hydrodynamic efficiency (10-20%) is one of important issues laser thermonuclear fusion.

Rice. 2. Radial distribution of temperature and density of matter in the target at the stage of acceleration of the shell towards the center

What processes can prevent the achievement of high compression ratios? One of them is that at thermonuclear radiation densities q > 1014 W/cm2, a significant fraction of the absorbed energy is transformed not into a classical electron thermal conductivity wave, but into streams of fast electrons, the energy of which is high more temperature plasma corona (so-called suprathermal electrons). This can occur both due to resonant absorption and due to parametric effects in the plasma corona. In this case, the path length of suprathermal electrons may turn out to be comparable to the size of the target, which will lead to preheating of the compressible fuel and the impossibility of achieving maximum compression. High-energy X-ray quanta (hard X-rays) accompanying suprathermal electrons also have great penetrating ability.

The trend of experimental research recent years is the transition to the use of short-wave laser radiation (l< 0,5 мкм) при умеренных плотностях потока (q < 1015 Вт/см2). Практическая возможность перехода к нагреву плазмы коротковолновым излучением связана с тем, что коэффициенты конверсии излучения твердотельного неодимого лазера (основного кандидата в драйверы для лазерного термоядерного синтеза) с длиной волны l = 1,06 мкм в излучения второй, третьей и четвертой гармоник с помощью нелинейных кристаллов достигает 70-80%. В настоящее время фактически все крупные лазерные установки на неодимовом стекле снабжены системами умножения частоты. Физической причиной преимущества использования коротковолнового излучения для нагрева и сжатия микросфер является то, что с уменьшением длины волны увеличивается поглощение в плазменной короне и возрастают абляционное давление и гидродинамический коэффициент передачи. На несколько порядков уменьшается доля надтепловых электронов, генерируемых в плазменной короне, что является чрезвычайно выгодным для режимов как прямого, так и непрямого сжатия. Для непрямого сжатия принципиально и то, что с уменьшением длины волны увеличивается конверсия поглощенной плазмой энергии в мягкое рентгеновское излучение. Остановимся теперь на режиме непрямого сжатия. Физический анализ показывает, что осуществление режима сжатия до высоких плотностей топлива оптимально для простых и сложных оболочечных мишеней с аспектным отношением R / DR в несколько десятков. Здесь R — радиус оболочки, DR — ее толщина. Однако сильное сжатие может быть ограничено развитием гидродинамических неустойчивостей, которые проявляются в отклонении движения оболочки на стадиях ее ускорения и торможения в центре от сферической симметрии и зависят от отклонений начальной формы мишени от идеально сферической, неоднородного распределения падающих лазерных лучей по ее поверхности. Развитие неустойчивости при движении оболочки к центру приводит сначала к отклонению движения от сферически-симметричного, затем к турбулизации течения и в конце концов к перемешиванию слоев мишени и дейтериево-тритиевого горючего. В результате в конечном состоянии может возникнуть образование, форма которого резко отличается от сферического ядра, а средние плотность и температура значительно ниже величин, соответствующих одномерному сжатию. При этом начальная структура мишени (например, определенный набор слоев) может быть полностью нарушена. Физическая природа такого типа неустойчивости эквивалентна неустойчивости слоя ртути, находящегося на поверхности воды в поле тяжести. При этом, как известно, происходит полное перемешивание ртути и воды, то есть в конечном состоянии ртуть окажется внизу. Аналогичная ситуация и может происходить при ускоренном движении к центру вещества мишени, имеющей сложную структуру, или в общем случае при наличии градиентов плотности и давления. Требования к качеству мишеней достаточно жестки. Так, неоднородность толщины стенки микросферы не должна превышать 1%, однородность распределения поглощения энергии по поверхности мишени 0,5%. Предложение использовать схему непрямого сжатия как раз и связано с возможностью решить проблему устойчивости сжатия мишени. Schematic diagram experiment in the indirect compression mode is shown in Fig. 3. Laser radiation is directed into the cavity (hohlraum), focusing on inner surface an outer shell consisting of a substance with a high atomic number, such as gold. As already noted, up to 80% of the absorbed energy is transformed into soft X-ray radiation, which heats and compresses the inner shell. The advantages of such a scheme include the possibility of achieving a higher uniformity of the distribution of absorbed energy over the target surface, simplification of the laser design and focusing conditions, etc. However, there are also disadvantages associated with the loss of energy for conversion into X-ray radiation and the complexity of introducing radiation into the cavity. What is the current state of research on laser fusion? Experiments to achieve high densities of compressible fuel in direct compression mode began in the mid-70s at the Physical Institute. P.N. Lebedev, where the density of compressible deuterium © 10 g/cm3 was achieved using the Kalmar installation with energy E = 200 J. Subsequently, work programs on LTS actively developed in the USA (the Shiva, Nova installations at the Livermore National Laboratory, Omega at the University of Rochester), Japan (Gekko-12), Russia (Dolphin at the Lebedev Physical Institute, Iskra-4", "Iskra-5" in Arzamas-16) at a laser energy level of 1-100 kJ. All aspects of heating and compression of targets of various configurations in direct and indirect compression modes are studied in detail. Ablation pressures of ~100 Mbar and microsphere collapse velocities V > 200 km/s are achieved with hydrodynamic efficiency values ​​of the order of 10%. Progress in the development of laser systems and target designs has made it possible to ensure a degree of uniformity of irradiation of a compressible shell of 1-2% under both direct and indirect compression. In both modes, densities were achieved compressed gas 20-40 g/cm3, and at the Gekko-12 installation a compressed shell density of 600 g/cm3 was recorded. Maximum neutron yield N = 1014 neutrons per flash.

CONCLUSION

Thus, the entire set of experimental results obtained and their analysis indicate the practical feasibility of the next stage in the development of laser thermonuclear fusion - achieving deuterium-tritium gas densities of 200-300 g/cm3, achieving target compression and achieving noticeable gain factors k at the energy level E = 1 MJ (see Fig. 4 and ).

Currently, the element base is being intensively developed and projects of megajoule-level laser installations are being created. The Livermore Laboratory began the creation of a neodymium glass installation with energy E = 1.8 MJ. The cost of the project is $2 billion. The creation of an installation of a similar level is planned in France. With this installation it is planned to achieve an energy gain of Q ~ 100. It must be said that the launch of installations of this scale will not only bring closer the possibility of creating a thermonuclear reactor based on laser thermonuclear fusion, but will also provide researchers with a unique physical object - a microexplosion with an energy release of 107-109 J, powerful source neutron, neutrino, x-ray and g-radiation. This will not only have great general physical significance (the ability to study substances in extreme states, combustion physics, equations of state, laser effects, etc.), but will also make it possible to solve special problems of an applied, including military, nature.

For a reactor based on laser fusion, however, it is necessary to create a megajoule-level laser operating at a repetition rate of several hertz. A number of laboratories are studying the possibilities of creating such systems based on new crystals. The launch of the experimental reactor under the American program is planned for 2025.

“We said we would put the Sun in a box. The idea is great. But the problem is that we don’t know how to create this box” - Pierre Gilles de Gennes, laureate Nobel Prize in Physics 1991.

While heavy elements There are quite a few elements required for nuclear reactions on Earth and in space in general; there are a lot of light elements for thermonuclear reactions both on Earth and in space. Therefore, the idea of ​​using thermonuclear energy for the benefit of humanity came almost immediately with an understanding of the processes underlying it - this promised truly limitless possibilities, since the reserves of thermonuclear fuel on Earth should have been enough for tens of thousands of years to come.

Already in 1951, two main directions for the development of thermonuclear reactors appeared: Andrei Sakharov and Igor Tamm developed a tokamak architecture in which the working chamber was a torus, while Lyman Spitzer proposed an architecture of a more intricate design in shape most reminiscent of an inverted Mobius strip not once, but several times.

The simplicity of the fundamental design of the tokamak allowed long time to develop this direction by improving the characteristics of conventional and superconducting magnets, as well as by gradually increasing the size of the reactor. But with an increase in plasma parameters, problems with its unstable behavior gradually began to appear, which slowed down the process.

The complexity of the stellator design completely led to the fact that after the first experiments in the 50s, the development of this direction stopped for a long time. It received a new lease of life quite recently with the advent of modern systems computer-aided design, which made it possible to design the Wendelstein 7-X stellator with the parameters and design accuracy necessary for its operation.

Physics of the process and problems in its implementation

Iron atoms have a maximum binding energy per nucleon - that is, a measure of the energy that must be expended to split an atom into its constituent neutrons and protons, divided by their total number. All atoms with lower and higher mass have this indicator below iron:

At the same time, in thermonuclear reactions of the fusion of light atoms up to iron, energy is released, and the mass of the resulting atom becomes slightly less than the amount masses of the original atoms by an amount that correlates with the released energy according to the formula E=mc² (the so-called mass defect). In the same way, energy is released during nuclear fission reactions of atoms heavier than iron.

During reactions of fusion of atoms, enormous energy is released, but in order to extract this energy, we first need to make a certain effort to overcome the repulsive forces between atomic nuclei which are positively charged (overcome the Coulomb barrier). After we have managed to bring a pair of atoms closer to the required distance, a strong force comes into play. nuclear interaction, which binds neutrons and protons. For each type of fuel, the Coulomb barrier for the start of a reaction is different, just as the optimal reaction temperature is different:

In this case, the first thermonuclear reactions of atoms begin to be recorded long before reaching average temperature substances of this barrier due to the fact that the kinetic energy of atoms is subject to the Maxwell distribution:

But the reaction at a relatively low temperature (on the order of several million °C) proceeds extremely slowly. So let’s say in the center the temperature reaches 14 million °C, but the specific power of the thermonuclear reaction in such conditions is only 276.5 W/m³, and it takes the Sun several billion years to completely consume its fuel. Such conditions are unacceptable for a thermonuclear reactor, since at such a low level of energy release we will inevitably spend more on heating and compressing thermonuclear fuel than we will receive from the reaction in return.

As the temperature of the fuel increases, an increasing proportion of atoms begin to have energy exceeding the Coulomb barrier and the efficiency of the reaction increases, reaching its peak. With a further increase in temperature, the reaction rate begins to fall again due to the fact that the kinetic energy of the atoms becomes too high and they “overshoot” each other, unable to be held together by the strong nuclear interaction.

Thus, the solution to how to obtain energy from a controlled thermonuclear reaction was obtained quite quickly, but the implementation of this task dragged on for half a century and has not yet been completed. The reason for this lies in the truly insane conditions in which it turned out to be necessary to place thermonuclear fuel– for a positive yield from the reaction, its temperature should have been several tens of millions of °C.

No walls physically could withstand such a temperature, but this problem almost immediately led to its solution: since a substance heated to such temperatures is a hot plasma (fully ionized gas) which is positively charged, the solution turned out to be on the surface - we just had to place such a heated plasma in a strong magnetic field, which will hold the thermonuclear fuel at safe distance from the walls.

Progress towards its implementation

Research on this topic is going in several directions at once:

1. By using superconducting magnets, scientists are trying to reduce the energy spent on igniting and maintaining the reaction;
2. with the help of new generations of superconductors, the magnetic field induction inside the reactor increases, which makes it possible to contain plasma with higher densities and temperatures, which increases power density reactors per unit of their volume;
3. research in the field of hot plasma and advances in the field computer technology allow better control of plasma flows, thereby bringing fusion reactors closer to their theoretical efficiency limits;
4. Progress in the previous area also allows us to keep the plasma in a stable state longer, which increases the efficiency of the reactor due to the fact that we do not need to reheat the plasma as often.

Despite all the difficulties and problems that lay on the way to a controlled thermonuclear reaction, this story is already approaching its ending. In the energy industry, it is customary to use the EROEI indicator - energy return on energy investment (the ratio of the energy expended in the production of fuel to the amount of energy that we ultimately obtain from it) to calculate fuel efficiency. And while the EROEI of coal continues to grow, this indicator for oil and gas reached its peak in the middle of the last century and is now steadily falling due to the fact that new deposits of these fuels are located in increasingly hard to reach places and at ever greater depths:

At the same time, we also cannot increase coal production for the reason that obtaining energy from it is a very dirty process and is literally taking the lives of people right now from various diseases lungs. One way or another, we are now standing on the threshold of the end of the era of fossil fuels - and this is not the machinations of environmentalists, but banal economic calculations when looking into the future. At the same time, the EROI of experimental thermonuclear reactors, which also appeared in the middle of the last century, grew steadily and in 2007 reached the psychological barrier of one - that is, this year for the first time humanity managed to obtain more energy through a thermonuclear reaction than it spent on its implementation. And despite the fact that the implementation of the reactor, experiments with it and the production of the first demonstration thermonuclear power plant DEMO based on the experience gained during the implementation of ITER will still take a lot of time. There is no longer any doubt that our future lies in such reactors.