Fokker-Planck analysis of electron cyclotron current drive experiments in DIII-D
Effects due to the ohmic electric field and electron trapping have been evaluated theoretically for electron cyclotron current drive experiments performed in the DIII-D tokamak. With both effects present experimentally, no analytic expression exists for predicting the resulting current drive efficiency. The dynamic interplay between the rf electric field, the ohmic electric field and the electron trapping has thus been evaluated using a 3-dimensional, bounced-averaged Fokker-Planck code. The computed electron distribution function in both real space and momentum space is also used to simulate the outputs of relevant diagnostics, such as non-thermal electron cyclotron emission (ECE). As a result of this detailed modelling, good agreement is found between theoretical predictions and experimental measurements, for both the driven current and the non-thermal ECE spectra. This approach makes possible the identification of the phase-space location of the emitting electrons, which is a notorious difficulty in the analysis of non-thermal ECE.
Bibliographic Reference: Paper presented: 18th European Conference of the EPS-Plasma Physics Division, Berlin (DE), June 3-7, 1991
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Record Number: 199110376 / Last updated on: 1994-12-02
Original language: en
Available languages: en