A school on applied superconductivity held near the Russian proton accelerator at the Protvino Institute for High Energy Physics (IHEP), near Moscow, provided a valuable snapshot of this important field and highlighted a long tradition of Russian expertise in this area.
Ever since the pioneering work by P L Kapitza in 1924 (for which he shared the 1978 Nobel Prize), there has been a continual interest in Russia in producing high magnetic fields and putting them to work. Much of this effort has been focused at Moscow’s Kurchatov Institute which also organizes an annual school on applied superconductivity for young engineers and scientists. At this year’s event, Evgeny Krasnoperov reviewed the devices for generating high magnetic fields developed at the Kurchatov Institute.
In 1939 F Bitter built high-field solenoid-type magnets which could generate stationary fields of 10 T. As early as 1972 the Kurchatov Institute exceeded 25 T by nesting a resistive magnet inside a large superconducting solenoid. Currently under construction is a new hybrid magnet to attain up to 30 T with superconducting coils based on niobiumtitanium and niobiumtin superconductor.
Russia is involved in the International Laboratory for High Magnetic Fields and Low Temperatures in Wroclaw, Poland. Lev Luganskij (Kapitza Institute) described the 30-year history of this laboratory, established by an agreement of the Academies of Sciences of the Soviet Union, German Democratic Republic, Bulgaria, and Poland.
Wroclaw
The Wroclaw laboratory is open to guests for experimental investigations of extreme magnetic fields and low temperatures. At present there are several magnets for stationary fields and one for pulsed fields up to 47 T. Several Bitter-type magnets and superconducting magnets produce a range of stationary fields. The largest Bitter-type magnet generates magnetic fields up to 20 T, its total power exceeding 6 MW. Bitter-type magnets are cooled by a two-circuit water cooling system.
Another important Russian magnetic contribution is tokamaks. In 1950, A D Sakharov and I E Tamm put forward the idea of magnetic confinement of high-temperature plasma and proposed the thermonuclear reactor tokamak concept. Sergey Egorov of the Efremov Institute (St Petersburg) covered the history and progress of these devices. The ultimate outcome is the International Thermonuclear Experimental Reactor (ITER), a fusion device to demonstrate ignition.
The ITER tokamak is currently being developed jointly by Euroatom, Russia, the USA, and Japan. The superconducting components are toroidal and poloidal field coils and a central solenoid, the latter producing a magnetic field up to 13 T at its inner radius. The superconducting coils for the system will require more than 1600 tons of niobiumtin.
In the Bochvar All-Russia Scientific Research Institute of Inorganic Materials (Moscow), niobiumtin wires for ITER have been developed and studied. Production of the first ton of ITER wire was completed in April 1998. Critical current density (non-copper cross-section) exceeds 550 A per sq. mm at 12 T.
A review of fabrication methods of niobiumtitanium and niobiumtin wire was presented by Victor Pantsirnyi. Victor Sytnikov (Cable Institute, Moscow) reported on ITER conductor development. The conductor is of cable-in conduit niobiumtin type with an incoloy alloy 908 external jacket, carrying 46 kA up to 13 T magnetic field. This international collaboration comprises 12 companies in Europe, Russia, Japan and the USA.
Subrata Pradhan (IPR, India) reported on the superconducting magnets for Tokamak SST-1. The superconducting cable for this project was produced in Japan and part of the cable was transported to Moscow in May. Superconducting model coils for the conductor testing will be fabricated and tested by the Kurchatov Institute.
Alexey Dudarev of the Kurchatov Institute reported on a 6 T superconducting wiggler. This three-pole wiggler was built at the Kurchatov Institute and successfully tested in the Chinese National Synchrotron Radiation Laboratory (800 MeV Hefei storage ring) in March. Its magnetic field is generated by three pairs of racetrack niobiumtitanium windings. The wiggler, with a short magnetic field period of 187 mm, enables an electron storage ring to provide a wider spectrum of synchrotron radiation.
Nikolai Chernoplekov, the Director of the Institute for Solid State Physics and Superconductivity, concluded the school with a review of several problems vital to the future of this field. The advent of warm superconductors has inspired new interest, with the promise of new (and as yet unknown) applications, or even a revolution in the traditional applications of superconductors.
