Role of ponderomotive density modification in IBW loading
- Lodestar Research Corp., 2400 Central Ave. P-5, Boulder, Colorado 80301 (United States)
We solve numerically a second-order nonlinear ordinary differential equation [1] that describes EPW-IBW mode transformation at the lower-hybrid layer, including self-consistent ponderomotive density profile modification, for the electrostatic potential in front of the IBW antenna. The model is solved for the particular case of heating just below the second harmonic of the deuterium cyclotron frequency. Background density and temperature profiles are chosen to be appropriate for the IBW experiments on TFTR. We calculate the complex antenna impedance, assuming vacuum within the antenna box, and a local reflectivity which reveal diminished antenna loading with increasing ponderomotive pressure, compared to the linear prediction. The ponderomotive force steepens the density gradient in the edge plasma, thus enhancing reflection and lowering the loading resistance. The model also describes the direct launch of IBWs in high edge density regimes, lacking a lower-hybrid layer, where the impedance is found to be much smaller than in the low density regime. {copyright} {ital 1997 American Institute of Physics.}
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FG02-88ER53263; FG03-97ER54392
- OSTI ID:
- 664826
- Report Number(s):
- CONF-9704102--
- Journal Information:
- AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 403; ISSN 0094-243X; ISSN APCPCS
- Country of Publication:
- United States
- Language:
- English
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