Electron cyclotron wave propagation and absorption in the Compact Ignition Tokamak

The possibility of heating the Compact Ignition Tokamak (CIT) with electron cyclotron power at 280 GHz (fundamental cyclotron resonance) is examined by simple analytic estimates and by detailed computational means. Efficient single-pass absorption of the ordinary polarization is accomplished by scanning the angle of injection of the microwave power from 60° to 90° relative to the toroidal magnetic field direction as the field intensity is ramped from 7 or 8 T to 10 T and the volume average beta increases from 0.4% to 2.8%. Efficient absorption occurs for the ranges of central density of (2-8) × 1020 m−3 and central temperatures of 5-20 keV. Thus, electron cyclotron resonance heating, using either gyrotrons or free-electron lasers, offers a reasonable heating scenario from the Ohmic phase to the ignition phase, even with a single-frequency radiofrequency source.