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(EX/P3-08) Modification of Boundary Plasma Behavior by Ion Bernstein Wave Heating on HT-7 Tokamak

Guoshen Xu¹⁾, B.N. Wan¹⁾, M. Song¹⁾, B.L. Ling¹⁾, C.F. Li¹⁾, J. Li^1)
 
1) Institue of Plasma Physics, Chinese Academy of Sciences, Hefei, China

Abstract.  Cooperated with Fusion Research Center, the University of Texas at Austin, U.S.A. The boundary plasma behavior during Ion Bernstein Wave (IBW) heating was investigated using Langmuir probe arrays on HT-7 tokamak. The particle confinement improvement of over a factor of 2 was observed in 30 MHz IBW heated plasma with RF power > 120 kW. The strong de-correlation effect of fluctuations resulted in that the turbulent particle flux dropped more than an order of magnitude. In IBW heated plasma, an additional inward E_r and associated poloidal E×B flows were produced, which could account for the additional poloidal velocity in the electron diamagnetic direction in the scrape-off layer (SOL). Three-wave nonlinear phase coupling increased evidently and low frequency fluctuations (about 5 kHz) were generated, which dominated the boundary turbulence during IBW heating. The 5/2-D resonant layer was located in the plasma edge region, which is found to be the mechanism underlying these phenomena.

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