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Investigation of lower hybrid wave damping in the PBX-M tokamak
- Source :
- Physics of Plasmas. 4:125-133
- Publication Year :
- 1997
- Publisher :
- AIP Publishing, 1997.
-
Abstract
- Lower hybrid (LH) current drive experiments on the Princeton Beta Experiment-Modified (PBX-M) [Phys. Fluids B 2, 1271 (1990)] have shown that the current profile can be changed by varying the phase velocity of the waves. The radial profile of the current carrying electrons was deduced from two-dimensional hard x-ray tomography. For a certain range of phase velocities, there is a correlation between the peak of the fast electron profile and the launched wave spectrum, despite the presence of a wide spectral gap between the phase velocity and the thermal electron energy distribution. A new model is proposed to explain how first-pass wave damping is possible in such plasmas. The rf power can form a tail of energetic electrons, and subsequently waves with moderate phase velocity can damp on them. For waves with very fast phase velocity, there must be an upshift of the n∥ spectrum for any damping to occur. These hypotheses are supported by ray tracing results which are coupled to relativistic Fokker–Planck cal...
Details
- ISSN :
- 10897674 and 1070664X
- Volume :
- 4
- Database :
- OpenAIRE
- Journal :
- Physics of Plasmas
- Accession number :
- edsair.doi...........5bdb5a2d12b728758110c13529d933df