Observations of Anisotropic Ion Temperature in the NSTX Edge during RF Heating

Technical Report · Thu Oct 21 04:00:00 EDT 2004

DOI:https://doi.org/10.2172/835926· OSTI ID:835926

Biewer, T M ^[1]; Bell, R E; Wilson, J R; Ryan, P M

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1. Princeton Plasma Physics Laboratory

A new spectroscopic diagnostic on the National Spherical Torus Experiment (NSTX) measures the velocity distribution of ions in the plasma edge with both poloidal and toroidal views. An anisotropic ion temperature is measured during the presence of high-power high-harmonic fast-wave (HHFW) radio-frequency (RF) heating in helium plasmas, with the poloidal ion temperature roughly twice the toroidal ion temperature. Moreover, the measured spectral distribution suggests that two populations are present and have temperatures of 500 eV and 50 eV with rotation velocities of -50 km/s and -10 km/s, respectively. This bi-modal distribution is observed in both the toroidal and poloidal views (in both He{sup +} and C{sup 2+} ions), and is well correlated with the period of RF power application to the plasma. The temperature of the hot edge ions is observed to increase with the applied RF power, which was scanned between 0 and 4.3 MW. The ion heating mechanism is likely to be ion-Bernstein waves (IBW) from nonlinear decay of the launched HHFW.

• Research Organization: Princeton Plasma Physics Lab., Princeton, NJ (US)
• Sponsoring Organization: USDOE Office of Science (SC) (US)
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 835926
• Report Number(s): PPPL-4012
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
DECAY
DISTRIBUTION
EDGE PLASMA
HEATING
HELIUM
ION HEATING
ION TEMPERATURE
PLASMA
RF HEATING
ROTATION
VELOCITY