Plasma formation and sustainment by a multijunction grill on the CASTOR tokamak

Radiofrequency power up to 40 kW, injected into the vacuum chamber of the CASTOR tokamak by a multijunction grill, was used for plasma production during the ramp-up phase of a toroidal magnetic field. When electron cyclotron resonance (ECR) appears inside the tokamak chamber for the given pumping frequency (f=1.25 GHz) plasma with a density greater than 2x1018 m-3 and a temperature of Te=10 to 40 eV is produced. The plasma is sustained at some lower value of density during the whole RF pulse. Simultaneously, a toroidal current of up to ≅ 0.2 kA is generated. The energy confinement time is estimated to be about 30 μs during the ECR breakdown. (author)