High-Harmonic Fast Wave Driven H-mode Plasmas on NSTX
Authors: B.P. LeBlanc, R.E. Bell, S.I. Bernabei, K. Indireshkumar, S.M. Kaye, R. Maingi, T.K. Mau, D.W. Swain, G. Taylor, P.M. Ryan, J.B Wilgen, and J.R. Wilson
Date of PPPL Report: May 2003
Presented at: the 15th Topical Conference on Radio Frequency Power in Plasmas, Grand Teton National Park, Moran, Wyoming, May 19-21, 2003
The launch of High-Harmonic Fast Waves (HHFW) routinely provides auxiliary power to NSTX plasmas, where it is used to heat electrons and pursue drive current. H-mode transitions have been observed in deuterium discharges, where only HHFW and ohmic heating, and no neutral beam injection (NBI), were applied to the plasma. The usual H-mode signatures are observed. A drop of the Da light marks the start of a stored energy increase, which can double the energy content. These H-mode plasmas also have the expected kinetic profile signatures with steep edge density and electron temperature pedestal. Similar to its NBI driven counterpart - also observed on NSTX - the HHFW H mode have density profiles that features "ears" in the peripheral region. These plasmas are likely candidates for long pulse operation because of the combination of bootstrap current, associated with H-mode kinetic profiles, and active current drive, which can be generated with HHFW power.