Turbulence Scattering of High Harmonic Fast Waves
Authors: M. Ono, J. Hosea, B. LeBlanc, J. Menard, C.K. Phillips, R. Wilson, P. Ryan, D. Swain, J. Wilgen, S. Kubota, and T.K. Mau
Date of PPPL Report: May 2001
Presented at: the 14th Topical Conference on Applications of Radio Frequency Powers in Plasmas in Oxnard, CA, May 7-9, 2001. Proceedings to be published by the American Institute of Physics (AIP).
Effect of scattering of high-harmonic fast-magnetosonic waves (HHFW) by low-frequency plasma turbulence is investigated. Due to the similarity of the wavelength of HHFW to that of the expected low-frequency turbulence in the plasma edge region, the scattering of HHFW can become significant under some conditions. The scattering probability increases with the launched wave parallel-phase-velocity as the location of the wave cut-off layer shifts toward the lower density edge. The scattering probability can be reduced significantly with higher edge plasma temperature, steeper edge density gradient, and magnetic field. The theoretical model could explain some of the HHFW heating observations on the National Spherical Torus Experiment (NSTX).