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Author(s):
S. Morimoto, M. Sato, H. Yamada, H. Ji, S. Okamura, S. Kubo, O. Motojima, M. Murakami, T. C. Jernigan, T. S. Bigelow, A. C. England, R. S. Isler, J. F. Lyon, C. H. Ma, D. A. Rasmussen, C. R. Schaich, J. B. Wilgen and J. L. Yarber
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Title:
Long Pulse Discharges Sustained by Second Harmonic Electron Cyclotron Heating Using a 35GHZ Gyrotron in the Advanced Toroidal Facility
Date of publication:
Sep. 1992
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Key words:
helical device, ATF device, steady-state plasma, ECH plasma, gyrotron
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Abstract:
A second hanmonic electron ccyclotron heating ( ECH ) discherge was sustained for ~ 20 s in the Advanced Toraidal Facility ( AT F ) at relatively weak magnetic field of B = 0.63 T. The high electron temperature ( T_eo ~ 700 eV ), helium plasmas were produced with ECH power of P = 100-200 kW from a 35 GHz gyrotron. The line-averaged electron density, bar{n}_e', and stored plasma energy, W_dia', were 2.3 x l0^18 m^-3 and 300-500 J, respectively. The stored energy follows closely the gyro-reduced Bohm confinement scaling law. The maximum discharge duration was limited by ECH pulse duration but not by plasma collapse. Diagnostic signals showed attainment of a quasi-stationary plasma and no impurity build-up was indicated by soft x-ray and VUV spectroscopic signals.
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