Two numerical ray tracing codes with focusing are used to compute lower hybrid daughter wave amplification by quasi-mode parametric decay. The first code, LHPUMP provides a numerical pump model on a grid. This model is used by a second code, LHFQM which computes daughter wave amplification inside the pump extent and follows the rays until their energy is absorbed by the plasma. An analytic model is then used to estimate pump depletion based on the numerical results. Results for PLT indicate strong pump depletion at the plasma edge at high density operation for the 800 Mhz wave frequency, but weak depletion for the 2.45 Ghz experiment. This is proposed to be the mechanism responsible for the high density limit for current drive as well as for the difficulty to heat ions.
Radiofrequency Plasma Heating: 6th Topical Conference
- Pub Date:
- July 1985
- Plasma heating by particle beams;
- Nonlinear phenomena: waves wave propagation and other interactions;
- Electrostatic waves and oscillations;
- Tokamaks spherical tokamaks