Experimental characterization of anomalous strong scattering of mm-waves in TEXTOR plasmas with rotating islands
- 9 October 2013
- journal article
- research article
- Published by IOP Publishing in Plasma Physics and Controlled Fusion
- Vol. 55 (11) , 115003
Abstract
Anomalous scattering of high power millimetre waves from gyrotrons at 140 and 110 GHz is investigated for plasma with rotating islands at TEXTOR. The magnetic field and plasma density influence the spectral content of the scattered waves and their power levels significantly. Anomalous strong scattering occurs in two density regimes, one at low densities and one at high densities, that also depend on the magnetic field. The two regimes are separated by a quiescent regime without anomalous scattering. Investigations suggest that scattering in the high-density regime is generated at the low-field side intersection of the gyrotron beam and the island position. The transition from the quiescent regime to the high-density regime occurs when the gyrotron frequency is twice the upper hybrid frequency at this position. There is some evidence that the scattering in the low-density regime is generated near the plasma centre. Under this assumption all the observed scattering is generated when the gyrotron frequency is near or below twice the upper hybrid frequency.Keywords
This publication has 41 references indexed in Scilit:
- Measurements of plasma composition in the TEXTOR tokamak by collective Thomson scatteringPlasma Physics and Controlled Fusion, 2011
- Electron and ion Bernstein waves excited in the ionosphere by high power EM waves at the second harmonic of the electron cyclotron frequencyGeophysical Research Letters, 2011
- Collective Thomson scattering of a high power electron cyclotron resonance heating beam in LHD (invited)Review of Scientific Instruments, 2010
- Low-threshold parametric decay instabilities in the experiments on the electron cyclotron resonance heating in tokamaks and stellaratorsJETP Letters, 2010
- Critical issues highlighted by collective Thomson scattering below electron cyclotron resonance in FTUNuclear Fusion, 2006
- NBI-driven ion cyclotron instabilities at the W7-AS stellaratorPlasma Physics and Controlled Fusion, 2003
- Lower hybrid turbulence excited by a fast transverse ion beam in a magnetized plasmaNuclear Fusion, 1998
- A quantitative study of scattering from electromagnetic fluctuations in plasmasJournal of Atmospheric and Terrestrial Physics, 1996
- Calculations of Thomson scattering functions for alpha particle diagnostics in JET plasmasNuclear Fusion, 1988
- Parametric Instability of Plasma Waves in a Magnetic Field, Due to High-Frequency Electric FieldsPhysical Review Letters, 1972