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Parametric decay instabilities driven by high power helicon waves in DIII-D.
- Source :
- AIP Conference Proceedings; 2023, Vol. 2984 Issue 1, p1-6, 6p
- Publication Year :
- 2023
-
Abstract
- High power helicon waves (whistler or very high harmonic fast lower hybrid waves) at a frequency of 476 MHz are being tested for efficient off-axis current drive on DIII-D with the goal of demonstrating profile control in AT plasmas [1-4]. In agreement with earlier theoretical predictions, strong Parametric Decay Instability (PDI) has been observed at injected RF power levels in the range of 0.05-0.5 MW with corresponding electric fields of 10-30 kV/m [5,6]. The dominant driver of the PDI is the E×B and the polarization drift velocity which can drive ion cyclotron quasi-modes and lower hybrid (or IBW) sideband waves unstable [5,6]. Initial experimental results have been obtained with powers up to 0.3 MW showing evidence of strong PDI measured with high-frequency one-turn magnetic probes located at both the outboard and the inboard wall at frequencies set by the usual selection rules [7,8]. Here we review the appropriate analytic formulation to predict such instabilities and present numerical evaluation of frequencies and growth rates relevant to DIII-D plasma parameters. We also assess the convective thresholds for the PDIs, and compared them with experimental observations. [ABSTRACT FROM AUTHOR]
- Subjects :
- OCEAN wave power
ELECTRIC fields
PLASMA confinement
Subjects
Details
- Language :
- English
- ISSN :
- 0094243X
- Volume :
- 2984
- Issue :
- 1
- Database :
- Complementary Index
- Journal :
- AIP Conference Proceedings
- Publication Type :
- Conference
- Accession number :
- 170021923
- Full Text :
- https://doi.org/10.1063/5.0163570