Enhancement of Mode-converted Electron Bernstein Wave Emission during NSTX H-mode Plasmas
Authors: G. Taylor, P.C. Efthimion, B. Jones, B.P. LeBlanc, and R. Maingi
Date of PPPL Report: August 2001
Published in: Physics of Plasmas 9 Issue 1, 167-170
A sudden, threefold increase in emission from fundamental electrostatic electron Bernstein waves (EBW) which mode convert and tunnel to the electromagnetic X-mode has been observed during H-mode transitions on the NSTX spherical torus plasma. The mode-converted EBW emission viewed normal to the magnetic field on the plasma midplane increases when the density profile steepens in the vicinity of the mode conversion layer, which is located in the plasma scrape off. The measured conversion efficiency during the H-mode is consistent with the calculated EBW to X-mode conversion efficiency derived using edge density data. Calculations indicate that there may also be a small residual contribution to the measured X-mode electromagnetic radiation from polarization-scrambled, 0-mode emission, converted from EBWs.