Parametric Studies of a Globus-3 Spherical Tokamak with Various Options of Electromagnetic Systems Based on Copper Alloys Using the GLOBSYS Code

• Published in: Physics of atomic nuclei Vol. 85; no. Suppl 1; pp. S17 - S33
• Main Authors: Mineev, A. B., Minaev, V. B., Sakharov, N. V., Bakharev, N. N., Bondarchuk, E. N., Voronova, A. A., Glushaev, A. M., Grigoriev, S. A., Gusev, V.K., Zhiltsov, N. S., Zapretilina, E. R., Kavin, A. A., Kiselev, E. O., Konin, A. Yu, Kudriavtseva, A. M., Kurskiev, G. S., Labusov, A. N., Petrov, Yu. V., Rodin, I. Yu, Tanchuk, V. N., Tel’nova, A. Yu, Trofimov, V. A., Filatov, O. G.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-12-2022; Springer; Springer Nature B.V
• Subjects: Analysis; Copper; Copper alloys; Copper base alloys; Electromagnetism; Liquid nitrogen; Magnetic fields; Overheating; Parameters; Parametric statistics; Particle and Nuclear Physics; Physics; Physics and Astronomy; Plasma; Plasma currents; Solenoids; Tokamak devices; Tokamaks; spherical tokamak; copper electromagnetic system; GLOBSYS system code; Globus-3; parametric studies
• ISSN: 1063-7788; 1562-692X
• DOI: 10.1134/S1063778822130099

The engineering part of the GLOBSYS code is presented, and the parameters of the Globus-3 facility, which is a development of the Globus program, are analyzed. The facility is primarily designed to provide a long pulse, a large toroidal magnetic field and strong heating. The concepts of searching for Globus-3 parameters under physical and engineering limitations are described. Obviously that reliable confinement and a large part of noninductive current are necessary to ensure existence of a plasma for a long time. Engineering constraints are involved in the choice of parameters in a more complex way: in some cases, it is overheating of the coils, in other cases, it is the total power supply, or the limit on the flux provided by the ohmic solenoid, or the strength of the constructions. The parameters of the Globus-3 spherical tokamak were preliminarily selected for the cases of a “warm” copper EMS (Electromagnetic system) and the EMS precooled to liquid nitrogen temperature. The exceeding of the duration of the plasma current plateau Δ
t
plateau
over the characteristic settling time of the plasma profiles τ
L
/
R
was chosen as the key condition. At values of the toroidal magnetic field
B
t
0
= 3 T, the condition Δ
t
plateau
> τ
L
/
R
cannot be attained even for precooled EMS. At
B
t
0
 = 2 T, only options with precooled EMS can be considered acceptable, but the facility dimensions are fairly large. For the field
B
t
0
= 1.5 T, the options with “warm” EMS correspond to the duration of the plasma current plateau ~3 s (Δ
t
plateau
/τ
L
/
R
~ 1–1.5). In the case of precooled EMS, the duration of the plateau can increase to 12–13 s (Δ
t
plateau
/τ
L
/
R
~ 5). In the latter case, as a basis for further development of the Globus-3 facility, options with the following geometric dimensions are reasonable:
R
0
~ 0.6–0.7 m,
a
 ~ 0.35–0.4 m,
А
 ≤ 1.7–1.8,
k
95
~ 1.7–1.8. The minimum allowable value of the plasma current
under the condition of effective absorption of the input power of neutral injection has been calculated. In the Globus-3 facility,
I
p
≈ 0.8 MA was chosen as the base value.