Explore chapters and articles related to this topic
Magnetic Nuclear Fusion in Tokamaks
Published in Sergei Sharapov, Energetic Particles in Tokamak Plasmas, 2021
In magnetic fusion, scientists explore the key property of plasmas to conduct electricity, so that plasma can be affected by electric and magnetic fields. Confinement of plasma by external magnetic fields is the focus of magnetic fusion. It is well-known that charged particles in magnetic field move on helical orbits, that is, they circle with Larmor radius perpendicularly to the field and move freely along the field. By bending the initially straight solenoid so that the two ends of the solenoid’s cylinder come together, one obtains a toroidal solenoid, as shown in Figure 1.3. Because this magnetic field toroidal topology has no open ends, charged particles flowing freely along the toroidal magnetic field move in circle Larmor orbits across the field and can remain inside the trap for a long time determined by transport processes across the magnetic field. If the toroidal loop with plasma is used as a secondary wing of a transformer, an electric inductive current IP starts flowing in the toroidal direction as plasma is a perfect conductor. This plasma current generates a so-called “poloidal” magnetic field BP in addition to the toroidal magnetic field BT induced by the solenoid coils. Schematically, this concept of a toroidal magnetic field machine with toroidal plasma current represents a tokamak [1.3]. Tokamaks were initially conceptualised in the 1950s by Soviet physicists I.E. Tamm and A.D. Sakharov and have become popular since 1970s [1.4].
MEPhIST-0 Tokamak for Education and Research
Published in Fusion Science and Technology, 2023
S. Krat, A. Prishvitsyn, A. Alieva, N. Efimov, E. Vinitskiy, D. Ulasevich, A. Izarova, F. Podolyako, A. Belov, A. Meshcheryakov, J. Ongena, N. Kharchev, A. Chernenko, R. Khayrutdinov, V. Lukash, D. Sinelnikov, D. Bulgadaryan, I. Sorokin, K. Gubskiy, A. Kaziev, D. Kolodko, V. Tumarkin, A. Isakova, A. Grunin, L. Begrambekov, R. Voskoboinikov, A. Melnikov
To simplify and lower the production costs of the toroidal magnetic system, it was decided to fashion it as a single continuous toroidal solenoid instead of as a number of separate toroidal coils. This decision allowed us to bypass the need for a complicated and expensive coil current synchronization system and to use only a single current supply line, rather than multiple lines for individual coils, thus minimizing the stray magnetic fields from them and the maintenance requirements. The downside of this type of design is that a preferential current direction exists in a toroidal solenoid. This can be compensated for in two ways. One can add a reverse current turn to the system, which severely complicates its construction. Alternatively, the shape of the toroidal solenoid can be optimized, specifically the distribution of the angle of inclination of the toroidal solenoid loops in the toroidal direction along the length of the loops. The second option was the one selected for the MEPhIST-0 toroidal field system.