HOME PROGRAM REGISTRATION HOTEL TRANSPORTATION SUBMIT ABSTRACT ABSTRACT LIST PROGRAM COMMITTEE MORE ON MADISON	Evidence for Fast-Electron Driven GAE Modes in Quasi-Helically Symmetric HSX Plasmas Author: Deng Chuanbao Coauthor: D.L. Brower,D.A. Spong,A. Abdou, A.F. Almagri, D.T. Anderson, F.S.B. Anderson, A.S.P. Gerhardt, K. L Institution : UCLA / UW-Madison Abstract text: Investigation of fast oscillations evident on interferometer, ECE radiometer and external magnetic probe time-series traces reveals the existence of high-frequency fluctuations in the range of 20-120 kHz. These fluctuations are observed in ECRH produced plasmas in the quasi-helically symmetric HSX device and are noted to have an m=1 nature. The fluctuations are coherent and global, peaking in the plasma core. The frequency range as well as the frequency scaling with electron density and ion mass are strongly suggestive of a global Alfven eigenmode (GAE). The Alfven continua for the n = 1 mode family for HSX was calculated and shows there exists gap for typical plasma parameters, an n=1, m=1 GAE mode may be excited within this gap. Fast electrons associated with ECRH are thought to be driving the instability. When the quasi-helical symmetry is broken, the mode is not observed. *Work supported by USDOE.