Electron Bernstein Wave Heating Scenarios for QPS
Abstract
Electron Bernstein Waves (EBW) are one option for heating the overdense plasmas in the proposed Quasi-Poloidal Stellarator (QPS). Two mode conversion processes generate EBW near the upper hybrid resonance layer. Direct-X involves the tunneling of an extra-ordinary wave between cutoff and the upper hybrid resonance layer. The direct-X process allows launch nearly normal to the plasma surface, but very steep density gradients are required to get efficient tunneling in QPS. The second process, O-X-B, uses an ordinary mode reflected as an extra-ordinary mode at cutoff, with the generation of EBW at the upper hybrid layer. The O-X-B process is not as sensitive to density gradient scale lengths as direct X, and can be nearly 100% efficient, but only within a very specific range of launch angles and polarizations. An impedance matching calculation can be used to model the mode conversion processes, but the subsequent propagation and absorption of the launched waves must then be determined using 3D ray tracing techniques. Launch angles, locations and polarizations for good EBW propagation and absorption in the QPS device will be discussed.
- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- October 2003
- Bibcode:
- 2003APS..DPPKP1045C