Fundamental studies of fusion plasmas. Final report, May 1, 1993--December 14, 1997

In the course of this grant, Lodestar has collaborated with the TFTR ICRF team to carry out an extensive investigation of rf-edge physics relevant to the understanding and operation of the TFTR fast wave (FW) and ion Bernstein wave (IBW) antennas. Their FW work covered four main areas: rf sheath geometry on TFTR, ICRF convective cells and edge profile modifications, impurity production, and plasma glow and Fermi acceleration. Their IBW work, carried out over the last two years, was in support of the IBW transport barrier and poloidal flow generation experiments. A theoretical survey of rf-edge physics expected to be critical for these antennas was carried out. While the physics that was known to be important for FW systems was considered (especially sheath power dissipation, edge density modifications, and impurities), additional physics enters for IBW waves because of the shorter wavelength, slower group velocity, larger electric fields and the different polarization. In particular, ponderomotive forces, while normally negligible in the FW context, can be substantial for the IBW, but the jitter excursion distance of an electron is too large for validity of the usual theory. A new model for the resulting electron heating and density expulsion was developed. A new model of antenna coupling to the electron plasma wave, mode transformation to the IBW, and the effect of reflected waves at the lower hybrid layer was also developed