| Autor: |
Porkolab, M., Pinsker, R. I., DeGrandchamp, G. H., Baek, S. G., Compernolle, B. Van, Denk, S., Petty, C. C., Tang, S. X., Thome, K. E. |
| Předmět: |
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| Zdroj: |
AIP Conference Proceedings; 2023, Vol. 2984 Issue 1, p1-6, 6p |
| Abstrakt: |
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] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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