Phase coherence of parametric-decay modes during high-harmonic fast-wave heating in the National Spherical Torus Experiment

Dataset · Wed Jun 01 00:00:00 EDT 2016

DOI:https://doi.org/10.11578/1366987· OSTI ID:1366987

Carlsson, J.  ^[1]; Wilson, J.R.  ^[1]; Horsea, J. ^[1]; Greenough, N. ^[1]; Perkins, R.  ^[1]

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1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

Third-order spectral analysis, in particular the auto bicoherence, was applied to probe signals from high-harmonic fast-wave heating experiments in the National Spherical Torus Experiment. Strong evidence was found for parametric decay of the 30 MHz radio-frequency (RF) pump wave, with a low-frequency daughter wave at 2.7 MHz, the local majority-ion cyclotron frequency. The primary decay modes have auto bicoherence values around 0.85, very close to the theoretical value of one, which corresponds to total phase coherence with the pump wave. The threshold RF pump power for onset of parametric decay was found to be between 200 kW and 400 kW.

• Research Organization: Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Fusion Energy Sciences (FES)
• DOE Contract Number: AC02-09CH11466
• OSTI ID: 1366987
• Resource Relation: Related Information: Physics of Plasmas, Vol 23, p 062519 (June 2016)
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Bicoherence Third order spectral analysis PDI HHFW NSTX