Non-resonant microwave discharge start-up in heliotron j

The non-resonant microwave discharge in strong magnetic fields was investigated in Heliotron J under the condition, omega(ce) /omega(MW)>1 (omega(ce) and omega(MW) are the angular electron cyclotron frequency and the angular microwave frequency, respectively). Following the production of a non-resonant microwave discharge plasma, it undergoes several phases in sequence: breakdown and formation of pre -ionized plasma, increase in linear and nonlinear phases of plasma density, and quasi -stationary stage. Several modes of non-resonant microwave discharge were investigated. In the power-scanning mode in non-resonant microwave discharge, a higher plasma density than that in the constant-power mode is achieved. The maximum average density achieved in the experiments is substantially greater than the critical density for 0 -wave (ordinary waves) 7.45.10(16) m(-3) and can reach the value of 2.5.10(18) m(-3).