The ZEPHYR poloidal field coils

The magnetic field of the poloidal coils creates plasma equilibrium conditions, plasma breakdown and heating and may be formed by two separate coil systems (OH; V). All coils without the central OH coil (OH 1) are normally stressed; less than 100 MPa. The extremely stressed OH central coil (350 MPa)must be specially designed for keeping stress and temperature rise low. The start temperature of OH 1 has to be less than 80 K for keeping the temperature rise < 130 K. The coil characteristics are: B = 27 T; ; t pulse = 4.5 s. All coils are designed for direct cooling. Cool medium can be Li N2 or supercritical He at high pressure.