The COMPASS magnetic coils are made of water-cooled copper and their main parameters are shown in Table 1 below.
The poloidal field (PF) coil system comprises the magnetizing (MF), equilibrium (EF), shaping (SF) windings and two windings for fast plasma positional feedback stabilization (FF). The design of the PF coils makes feedback control of the plasma current, position and shape relatively simple and independent. The reconfiguration of the circuit is possible using the linkboard to cope with different types of experimental requirements.
The 16 equi-spaced toroidal field (TF) coils are located outside the PF coils (Fig. 1). The maximum toroidal magnetic field is 2.1 T what corresponds to the current in TF coils of approximately 92 kA. Concerning The COMPASS TF field consumes more then 50 % of the total tokamak energy requirements.
Fig. 1: Model of the COMPASS toroidal and poloidal field coil system.
|
Toroidal field (TF) |
|
|
TF on axis |
0.8 – 2.1 T |
|
rise time |
~ 1 s |
|
flat top current duration |
1 s at 1.2 T; 0.5 s at 2.1 T |
|
decay time |
~ 1 s |
|
Total inductance |
2.5 mH |
|
Total Resistance (20 °C) |
2.7 mΩ |
|
Poloidal fields (PF)
|
|
|
Max. plasma current |
350 kA |
|
Flat top time without NBI or RF current drive |
100-400 ms |
|
Flat top time with RF current drive |
≤ 1 s |
|
Flux swing |
0.82 Vs |
|
Current rise time |
~ 30-100 ms |
|
Triangularity |
~ 0.5 |
|
Elongation |
~ 1.6 |
|
Fast feedback fields (FF)
|
|
|
Max. vertical FF on axis |
200 mT |
|
Feedback response time |
≤ 300 µs |
|
Max. radial FF on axis |
10 mT |
|
Feedback response time |
≤ 100 µs |
Table 1: Characteristics of magnetic field coil system
