Investigation of lower hybrid wave damping in the PBX-M tokamak

S. Bernabei, A. Cardinali, G. Giruzzi, G.T. Hoang, D. Ignat, R. Kaita, M. Okabayashi, F. Paoletti, S. Von Goeler

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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 profileand 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 calculations of the electron distribution function. © 1997 American Institute of Physics.
Original languageEnglish
Pages (from-to)125 - 133
Number of pages9
JournalPhysics of Plasmas
Volume4
Issue number1
DOIs
Publication statusPublished - 1997
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics

Cite this

Bernabei, S., Cardinali, A., Giruzzi, G., Hoang, G. T., Ignat, D., Kaita, R., ... Von Goeler, S. (1997). Investigation of lower hybrid wave damping in the PBX-M tokamak. Physics of Plasmas, 4(1), 125 - 133. https://doi.org/10.1063/1.872122