Central solenoid for spherical tokamak Globus-M

The central solenoid is a critical component of the spherical tokamak Globus-M (plasma major radius R = 0.36 m, plasma minor radius a = 0.24 m, aspect ratio R/a = 1.5 toroidal magnetic field B-T less than or equal to 0.62 T plasma current I-P less than or equal to 0.5 MA). The two-layer solenoid, 1312 mm long with a 200-mm outer diameter is located between the 112-mm-diam inner rod of the toroidal field coils and the 217-mm-diam inner cylinder of the vacuum vessel. Strong magnetic and thermal cyclic loads acting on the solenoid require that it be manufactured from a high-strength hollow conductor The conductor material selected for the solenoid winding is CuAg0,1(OF). Advanced manufacturing technology has made it possible to increase the continuous length of conductor (with an similar to 20 x 20 mm(2) cross section) up to the 66 m that is required for Globus-M. To verify the winding procedure, a one-sixth-length solenoid prototype has been constructed and tested with loads exceeding the design loads acting on the full-scale solenoid. The tests included magnetic and strain measurements. The results are in satisfactory agreement with structural analysis.