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P: Plasmaphysik
P 8: Magnetic Confinement and Plasma Technology (Poster Session)
P 8.18: Poster
Monday, April 2, 2001, 12:30–15:00, AT2
An antenna for Electron Bernstein heating of the Pegasus spherical tokamak — •Anja Mück1, Hartmut Zohm1, Walter Kasparek2, and Cary Forest3 — 1Max-Planck-Institut für Plasmaphysik, EURATOM Assoziation, Boltzmannstr. 2, 85748 Garching — 2Institut für Plasmaforschung, Universität Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart — 3University of Wisconsin - Madison, 1150 University Ave, Madison, WI 53706, USA
In a spherical tokamak, due to the low cut-off density ne= 1017 1/m3, direct electron cyclotron heating is not possible. However, the conversion from ordinary to extraordinary mode at the plasma cut off layer and from extraordinary to Bernstein mode at the upper hybrid frequency is supposed to make the access of electron cyclotron waves to the plasma center possible. The antenna system is a combination of a rotatable elliptical reflector and a feed antenna. To optimize the conversion process quasi circular polarization is needed which determines the helical shape of the feed antenna. The antenna design for the spherical tokamak Pegasus, Madison, WI, is presented. The construction offers the possibility to verify experimentally the occurrence of the O-X-B mode conversion process and its angular dependence at a frequency of f=2.9 GHz.