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Electron heating and superthermal electron enhancement due to electron cyclotron heating in ISX-B at 28 GHz

Technical Report ·
DOI:https://doi.org/10.2172/6296208· OSTI ID:6296208

A series of electron cyclotron heating (ECH) experiments was performed with a 28-GHz gyrotron on the Impurity Study Experiment (ISX-B) tokamak at Oak Ridge National Laboratory. Up to 70 kW of microwave power was injected into ISX-B from the high field side. Bulk heating was observed with a central temperature rise of approx. 370 eV from an original temperature of approx. 600 eV, as measured by Thomson scattering. With ECH and under low density conditions, large nonthermal signals were observed on electron cyclotron emission diagnostics at the first, second, and third harmonics. These signals sometimes became quite large after the end of the ECH pulse. The effects observed can be attributed to relatively small changes in the electron distribution function. The temporal behavior of the enhanced emission is tentatively attributed to the pitch angle scattering of superthermal electrons.

Research Organization:
Oak Ridge National Lab., TN (USA)
DOE Contract Number:
W-7405-ENG-26
OSTI ID:
6296208
Report Number(s):
ORNL/TM-8403; ON: DE83012307
Country of Publication:
United States
Language:
English