Two schemes for auxiliary ECR plasma heating for the GDMT project, operating at frequencies of 82.6 GHz and 170 GHz, are compared. The choice of frequencies is determined by the availability of domestic megawatt-power gyrotrons manufactured by JSC GYCOM. Both schemes use transverse launch of radiation relative to the trap axis with focusing near the X-point of the magnetic field, and operate with the same (within 3%) resonant magnetic field. The 82.6 GHz heating is based on the absorption of the ordinary wave at the fundamental cyclotron harmonic, while the 170 GHz heating is based on the absorption of the extraordinary wave at the second cyclotron harmonic. The feasibility of efficient plasma heating with both schemes is demonstrated by simulations of the microwave field interaction with the GDMT plasma using the QOOT quasi-optical code. However, the 170 GHz heating scheme has revealed a number of advantages that suggest it as the best option providing the greatest reliability and flexibility for physical experiments at GDMT.
Gospodchikov et al. (Wed,) studied this question.