ITERatsiya superconductivity

In 2011, physicists around the world celebrated the 100th anniversary of the grand event — the opening of the Dutch scientist Heike Kamerlingh Onnes phenomenon of superconductivity. On the history, the present and the prospects for the development of applied superconductivity us the deputy director of the Kurchatov NBIKS center, head of scientific-technological complex of superconductivity Alexander K. Shikov

Of what, what does … 

— I do superconductivity for more than 40 years. Upon cooling, a variety of materials to a very low boiling temperature of liquid helium. ie minus 269 ° C — electric resistance becomes zero. This is the superconductivity. In 1913, Mr. X. Kamerlingh Onnes discovered superconductivity destruction of the magnetic fields and currents. It was only in the mid-1960s .. when Soviet scientists Lev Landau. Alexei Abrikosov and Vitaly Ginzburg developed the theory of superconductivity, there was hope that the superconducting materials will be used in the technique, as they are able to maintain the current-carrying capability in high magnetic nolyah. They were called type II superconductors. Scientists for it was awarded the Nobel Prize, but only in 2003, in all, for his work on superconductivity are now six Nobel Prizes, one of the last — for the discovery of high-temperature superconductors.

Studies on Applied Superconductivity actively began to develop in the Soviet Union in the mid-1960s. The initiator and organizer was Kurchatov Institute. Together with the Kurchatov Institute of Inorganic Materials. Academician AA Bochvar first to develop a low-temperature composite superconductors based alloys and compounds. When in the late 1980s. were discovered high-temperature superconductors that lose resistance even at the temperature of liquid nitrogen-minus 196 ° C. — we quickly got composites based on them.

— What materials are used in superconductors and whether technological "tricks" of their production?

— The first technical materials created by the Kurchatov Institute and VNIINM were superconductors based on zirconium and niobium (Nb-Zr). Unfortunately, this alloy was not very technologically advanced. of it was difficult to produce the desired temperature superconductors design. A design of the superconductor is also amazing: imagine provodnichok diameter of 0.5-1 mm. up to 20 km, the matrix consisting of copper, and this copper ultrapure and distributed in the matrix of several thousand fibers with a diameter up to 10 microns of a superconducting material. Soon superconductors have been developed on the basis of niobium-titanium alloys (Nb-Ti). They have been widely used since the resistance due to the zero root can pass through huge currents inch — about several millions of amperes, while a traditional electrical equipment can only pass current to one thousand A. If the superconductor is wound into a coil and to solenoid through which pass high current, it can create a strong magnetic field. Thus in 1979. for the first time in the world, at the Kurchatov Institute appeared installing fusion "Tokamak-7" (toroidal chamber with magnetic coils) on niobium-titanium superconductor.

Soon, the Kurchatov Institute, a new idea was born to create a setup-fusion using superconductors based on niobium-tin (Nb Sn). This compound was much better than its predecessors in all properties, including the critical current (which is not "kill" the superconductivity), the critical temperature (cooling to which the compound loses its resistance) and the upper critical field (in excess of this field is also "kills" superconductivity). In 1988, for the first time in the world, at the Kurchatov Institute developed the "Tokamak-15" on the niobium-tin superconductors. It was the first and very important step towards the realization of the idea of a fusion power plants, laid the foundations for an international project 1TER. From about the middle of the 1980s. Kurchatov participate in this global international project.

In 1988, for the first time in the world, at the Kurchatov Institute developed the "Tokamak-15" on the niobium-tin superconductors. It was a very important step towards the realization of the idea of a fusion power plants, laid the foundation for the international ITER project

— The advantages of the new material are obvious. At least in theory. What we have in practice?

— In practice, Nb3Sn there is one problem. Nb-Ti — an alloy of it by the joint deformation of the composite components can be manufactured stranded conductor, and the compound Nb3Sn-is brittle like glass, intermetallic, and from this it was necessary to make the wire can be wound from which a magnetic system. However, this problem was solved Kurchatov Institute and VNIINM by the so-called "bronze technology." We have the same method of co-produced composite deformation, but instead of copper matrix consisted of tin bronze — an alloy of copper and tin, and the fibers were not made of an alloy of niobium-titanium, and from ultra-pure niobium. Then, a composite was subjected to heat treatment. whereby tin diffused into iiobievye core to form brittle intermetallic compounds Nb3Sn at the edges of these veins. Eventually been developed the superconductor comprising a diameter of 1.5 mm 7225 fibers. When the diameter of each strand 5mk., Which is ten times smaller than the diameter of a human hair, the length of the conductors then was about 5 km away. With the use of such material and was made the world’s first superconducting magnet system for the "Tokamak".

— Consequently, the hope for a speedy establishment of such materials was not enough?

— We also thought that it would take a very long time. before you will be able to achieve such performance. In 1992, the International Organization for ITER was a competition for the development of superconductors, which was attended by 17 world manufacturers, including VNIINM, Kurchatov Institute and the Research Institute of the cable industry and the Research Institute of Electro equipment — is four, which has successfully created a magnetic system, the basics "Tokamak-7" and "Tokamak-15."

Particularly difficult was the task of developing a metallurgical technologies of superconductors. We needed not just a tin bronze or niobium, and high-purity metals and alloys to provide them with an extraordinary plasticity. It was necessary to obtain in the metal matrix hyperfine "veins" without breaks over a length of 20 km. But few get these "veins" whole, it is necessary to provide them with a special nanostructure, which would allow to achieve high current-carrying capacity. Today, all the talk about nanotechnology, but we already knew: without the creation of a superconductor nanostructures to achieve this goal would be impossible, and we have successfully coped with the development of such technologies. Of the 17 firms, only four developed superconductors with the required level of properties, i
ncluding Russian specialists.

Was not easy, and the process of participation in the tender. We had to get a 100-meter long pieces of wire, cut them into ten parts, and send in ten laboratories in the world to avoid the "evil" of the results, that all was confirmed. Setting ambitious, and properties must be guaranteed. Of the ten laboratories came the reply that the Russian-temperature superconductors based alloy niobium-titanium and niobium-based compounds tin fully meet the highest international standards.

Then it was necessary to make the so-called current-carrying elements. Fact. that such a wire at the temperature of liquid helium can carry currents of the order of hundreds of amperes in a magnetic field strength up to 5 T (for Nb-Ti) and 12 T (for Nb3Sn). However, the need thousands of amperes that the winding could contain the plasma. To increase the current carrying capacity of superconductors weave in tow. In one bundle of wires over one million, with a wiring has a structure defined porosity. It is placed in a tube through which circulates the liquid helium and helium can penetrate the pores and each wash wire, thereby converting it into a superconducting state. And a current-carrying element with a diameter of 40 mm in a magnetic field of 12 T can hold a 120-thousand A., and without the field, which is bad for the superconductivity. — Several million amperes. The length of this section shall be 765 m

Initially, it was necessary to make a sample length of 4 m sending it to Switzerland, in the Paul Scherrer Institute, and measuring the properties of the laboratory was to confirm that with the resulting current-carrying element of all is in order: it is not broke in the redistribution of cable, the pores are not trapped, helium is much penetrate and that cool. We are looking forward to the result, and he was also successful. So again we have satisfied all the requirements and to this guide.

Next, it was necessary to make a prototype of the magnetic system — the so-called coil-insert. It is a magnet diameter of 2 m height of 5 meters weighing 7 tons, for it required a ton of superconductor. Commonwealth VIIINM, the Kurchatov Institute, and VNIIKP NIIEFA successfully solved and the task: a ton of superconductor was made out of it — the current-carrying element of the current-carrying element-Coil insert. Her transported from St. Petersburg by plane to Japan, where tests were carried out, which also were successful: the Russian-coil insert at liquid helium temperature has reached operating current of 43.1 kA. Thus, we have the right to make a significant contribution to the international project.

Emergency resuscitation

— But the capacity at that time was not. How to come out of this situation?

— Russia won the bid to manufacture 220 tons of the superconductor, about a third of the total. This major order was impossible to perform in institutions. This supertehnologichnogo production was to create a commercial scale at the plant where there is a culture of production and highly skilled professionals. At the time, I was Deputy Director General VNIINM and was responsible for the reconstruction of the zirconium production Chepetz mechanical plant in the city of Glazov in Udmurtia, and, together with colleagues from the Kurchatov Institute and the "Rosatom" We chose this plant for production of superconductors. In 2002, the head of Minatom A. Rumyantsev signed a decree on the establishment of such proceedings. I was appointed supervisor of the development of technology and organization of production. The work was no end, because it was also necessary to establish the production of source materials: pure copper, tin bronze vysokogomogennoy, vysokogomogennogo alloy Nb-Ti, ultra-pure niobium composites themselves and their semi-finished products.

In the short time at Chepetz mechanical plant fuel company TVEL SC "Rosatom" were prepared five large halls. To purchase from leading foreign and domestic firms VNIINM equipment specialists, the technology, and scientists of the Kurchatov Institute developed the methods of diagnosis of these materials-determination of the critical currents, the critical temperature, the quality of the copper, the homogeneity of properties along the length — more than 40 certified methods were applied in order to certify materials on international standards.

By that time, decided that ITER will be built in France, near Marseille, in the town of Cadarache. All participating countries, to which China, Korea and India signed a decision to build. In April 2009 we launched the production. Began large-scale production of superconducting material. Were put into production in the Podolsk cable compartment VNIIKP dzheketirovaniya line and in the Institute of High Energy Physics (IHEP), which is now part of the Research Center "Kurchatov Institute".

By the end of 2012 has already produced more than half of the superconductor. Manufactured seven niobium-tin current-carrying elements that fully comply with the highest international standards: two of them in October 2012 sent to Italy, where they have to put insulation, heat-treated and then sent to France for the creation of the magnetic system of the reactor. In total we have over 2.5 years to make and check about 30 such current-carrying elements. They are a reel diameter of 4 m and a height of more than 5m. weighing about 10 tons. within which the conductor — a current-carrying element — and distributed. The material has to drive at night from Protvino in the Kurchatov Institute, accompanied by the traffic police. because this oversized cargo.

We also need to put on a construction site 39 pieces of niobium-titanium superconductor in the form of a cable. Thus, in Russia there was a unique large-scale production of superconductors. Experts from the central command ITER, which is located in Cadarache, traveled around the world, visited the production — 12 plants — and recognize the Russian production of one of the most modern and sophisticated.

— Large-scale use of superconductors in industrial physics-not a new phenomenon. But for the average person is like a parallel reality. Is there a "national economic" use of superconductivity in?

— Certainly. This, for example, medical scanners, which allow to investigate the level of the cell processes, including those leading to the formation of malignant tumors at a very early stage, allowing them to timely detect and take action to eliminate it. The magnetic system of the MRI is also made of Nb-Ti-superconductor. At present, such a superconductor has put Russia on a number of companies which have confirmed its suitability for MR applications, and expressed their willingness to consume it in a volume of up to 100 tonnes a year. The question and the establishment of joint production of MR scanners with one of the foreign companies using Russian-temperature superconductors.

Increasing degrees

— Now a few words about the high-temperature superconductors.

— In 1986 high-temperature superconductors were discovered that, unlike the low temperature, resistance to losing at the boiling temperature of liquid helium, lose resistance to boiling temperature of liquid nitrogen. Swiss scientists Johannes Bednorz and Karl Muller discovered these chemicals, but they were ceramics — LaSrCuO. then YB
aCuO and more complex — BiSrCaCuO. The transition itself from liquid helium to liquid nitrogen promised a revolutionary change in the entire electrical engineering, electricity, and medicine. ie in areas where the superconducting material. For example, the power of the electric motor can be increased without changing the overall size is four to five times, or, conversely, for the same power to reduce the weight and dimensions, too, at times. It was possible to carry current without losses over long distances. For the power it offers tremendous prospects.

We all my life dealing with superconducting materials. understand that this is a task for the long term. In Nb3Sn only two elements — niobium and tin are bismuth, strontium, calcium, copper, oxygen — is ceramic. Nevertheless, enthusiasm throughout the scientific world has been enormous, endless seminars were held, collecting a huge number of people. But over time, wanting to do such a difficult job had less, but we continued to strengthen the work in this direction, despite difficult for Russian science 1990s. We have made ribbon conductors based on bismuth and ceramics — the first generation of high-temperature superconductors. Imagine a ribbon width of 3-4 mm and a thickness of 0.1-0.2 mm. which contained 1539 living diameter of 15-20 microns of ceramic. And such a ribbon could be bent with a certain radius, which is called the critical current capability without breaking.

As a result, the technology was developed for preparing such superconductors up to 1 km. but the matrix should be made of silver. We experienced about 20 metals, and all of them were oxidized, and hence were taken from a combination of oxygen, leading him to an inadequate structure, which no longer had the superconducting properties. Silver not only incorporate oxygen: moreover, this compound could saturate oxygen through the silver and attain high critical properties, such that the material loses its resistance to liquid nitrogen temperature. Unfortunately, so far based superconductors such ceramics can not achieve a structure that would maintain the current-carrying capacity at high magnetic nolyah. As yttrium ceramics has better properties at high fields and more promising. But it is difficult to make out any stray strands, so technicians have gone through the creation of strip conductors.

In the mid-2000s .. when the director of the Kurchatov Institute was Mikhail V. Kovalchuk, we discussed with him the need to adopt comprehensive measures for the development of such a material, especially for the electric power industry. MV Kovalchuk collected at the Kurchatov Institute, all interested parties have discussed all the details, and then he initiated together with the GC "Rostatom" and the Ministry of Energy launched a large-scale government project for the creation and use of high-temperature superconductors. which consisted of two parts. The first — the development of high-temperature superconductors with an acceptable level for technical use characteristics. The second is devoted to the creation of devices that operate using superconducting material. In this project, the Kurchatov Institute commissioned the hardest part, the development of technologies and increase the current-carrying capacity of conductors.

— What is the structure of the superconductor tape?

— It is very difficult: the substrate comprises stainless steel or nickel alloy with tungsten. These alloys have a crystal lattice, and ceramics — the other. To achieve the coupling and to avoid peeling, you need to create several intermediate layers of certain oxides-so "layer cake" allows you to have a superconductor with the set of physical and mechanical properties. At the Kurchatov Institute will be established production line but hundred-meter pieces of such superconductors, and in parallel, we will explore the relation of composition and structure of superconducting ceramics with properties for the purpose of promotion. At the Kurchatov Institute has established a powerful, not only in Russia but also in the world of complex materials research, including synchrotron and neutron sources, and is a unique combination. The theory and experiments suggest. that the current-carrying capacity compared to today you can pick up another four to five times. This multi-year painstaking dirty work that needs to succeed.

— What devices can use such tape superconductors?

— First of all, current limiters, devices that allow ten times faster to disable the network if it has undergone some kind of trouble, such as a short circuit. This allows you to extend the shelf life of various equipment and keep it off. Current limiters are also widely used in the railway, power networks. The second type of device — this current leads that provide large magnetic energy of the system, such as the Large Hadron Collider, in the long term — for fusion reactors. Finally, the third application — this is the power lines. High-temperature superconductivity will enter into the daily life on a much larger scale than it has entered into an industrial physics. Of course, it will bring revolutionary changes in these areas, because the energy input into the city now hampered by the high cost of land, and it will be able to enter through smaller channels more energy. Our colleagues from the Research Institute of the cable industry. we are working on ITER, created Europe’s largest segment of current-carrying elements of length 220 m — it is installed and successfully tested in the SEC power. Federal Grid Company with the participation of the Kurchatov Institute launched a project transmission line has a length of 2.5 km to Saint-Petersburg. But this is not the limit. For example, today we calculate the lining of the electricity cable from Russia to Japan on the ocean floor, not to trade in oil and gas, and a product with a high added value — electricity.

— But cooling costs while still be felt. This raises the question: can theoretically superconductivity at room temperature?

— When high-temperature superconductivity was not open yet, we discussed this matter with VL Ginsburg, and he pointed out that the theory does not prohibit this. Moreover, Ginzburg’s once published a book dedicated to the superconductivity, which refers to room temperature. I think that the superconductivity, is an area of physics that even today there are substances, and possibly a liquid or a gas, or even organic compounds that possess superconductivity at room temperature. Sorry. we still have not found them yet, but I’m sure they are, and work experience in superconductivity says that the theory of knowledge, experimentation with lots of supplies will get those superconductors that have better properties. The theory gives a direction, and the search must still be experimental.

From the beginnings to world record

— How do you interact with the rest of the Kurchatov Institute?

— In the USSR, the work has proceeded as follows: Kurchatov Institute was the center from which came primarily physical ideas. Once the idea was born a physical, necessary materials to carry it out. Nuclear Project — the most striking example, because there was no uranium or plutonium, or construction materials, all of this had to be developed to create the country’s nuclear shield. For this was organized VNIINM. Product designs created Arzamas and Snezhinsk. One of the main features of the Kurchatov Institute, the alignment of the entire chain, from concept to manufacturing. I am a specialist in materials created by a whole range of new materials can not trace it. Today, our Research Center "Kurchatov Institute" generates ideas, designs and materials technology makes the pilot samples. It is very true that is concentrated in one place the whole complex — from the idea to the car. Ac
tually, superconductivity — is also the clearest example: if physicists, technologists, materials scientists, engineers every day did not interact with each other on the same site of the Kurchatov Institute, then to achieve such success would be very difficult.

— And what about the young staff?

— In 2011 at the initiative of M. Kovalchuk and MN Strikhanov was created Department of Applied Superconductivity at the Moscow Engineering Physics Institute, and I was asked to head it. At present, our experts give lectures at Moscow Engineering Physics Institute and the Kurchatov Institute. Practice basic research and technology of new materials is very fond of them, because they see the final result. Impressive and modern facilities in which we operate. For the past two years, we accept popyat young graduate students, and they pass a comprehensive interview. and we only get mc guys who are willing to devote themselves to the cause of interesting — the development of superconductors and their use.

— Has your work "side effects" when from the mainstream there are "branches"?

— For example, multi-core technology of superconductors at the Kurchatov Institute for more than 20 years ago, it was proposed to create a material for pulsed magnetic fields — about 50-100 Tesla. But. Unfortunately, ordinary electrical equipment, copper, aluminum, could not withstand those loads that have evolved in this magnet with a pulse. Then the idea to use magnets to create a pulse Nb-Ti-temperature superconductors, but to use them in ultra-pure copper wire and Nb-Ti of the reinforcement to the copper matrix. Kurchatov "tokamak" superconductors have set a world record was achieved 50Tl field. Then we started to increase the amount of reinforcing cores, improving mechanical properties. In various laboratories around the world that manufacture magnets made of composites, developed by the Kurchatov Institute and VNIINM, this material has become extremely popular. In March 2012, the United States, the Los Alamos National Laboratory of High Magnetic Fields on the solenoid made of a unique Russian composite material comprising at section 4×6 mm (rectangular conductor) 450 000 000 Nb filaments of 10 nm each, failed to reach 100.1 Tesla. The material has the strength of steel, electrical conductivity of about 70% of the conductivity of copper, and most importantly, we managed to keep it plasticity. This is an example of how a knowledge-based technology creates another. Therefore, we have in front of a lot of very interesting and important work. and I’m grateful for that. she tied me up with superconductivity. |

Interview by Victor Friedman

In the world of science 01.2013

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