Ion Bernstein wave experiments on the Alcator C tokamak

Technical Report · Thu Sep 01 04:00:00 EDT 1988

OSTI ID:6856544

Moody, J D

Ion Bernstein wave experiments are carried out on the Alcator C tokamak to study wave excitation, propagation, absorption, and plasma heating due to wave power absorption. It is shown that ion Bernstein wave power is coupled into the plasma and follows the expected dispersion relation. The antenna loading is maximized when the hydrogen second harmonic layer is positioned just behind the antenna. Plasma heating results at three values of the toroidal magnetic field are presented. Central ion temperature increases of ..delta..T/sub i//Ti /approx lt/ 0.1 and density increases ..delta..n/n < 1 are observed during rf power injection of up to 180kW at a frequency of 183.6 /times/ 10/sup 6/s/sup /minus/1/ for plasmas within the density range 0.6 /times/ 10/sup 20/m/sup /minus/3/ less than or equal to /bar n//sub e/ less than or equal to 4 /times/ 10/sup 20/m/sup /minus/3/ and magnetic fields 2.4 greater than or equal to ..omega../..cap omega../sub H/ greater than or equal to 1.1. The density increases is usually accompanied by an improvement in the global particle confinement time relative to the Ohmic value. The ion heating rate is measured to be ..delta..T/sub i//P/sub rf/ approx. = 2-4.5 eV/kW at low densities. At higher densities /bar n//sub e/ less than or equal to 1.5 /times/ 10/sup 20/m/sup /minus/3/ the ion heating rate dramatically decreases. It is shown that the decrease in the ion heating rate can be explained by the combined effects of wave scattering through the edge turbulence and the decreasing on energy confinement of these discharges with density. The effect of observed edge turbulence is shown to cause a broadening of the rf power deposition profile with increasing density. It is shown that the inferred value of the Ohmic ion thermal conduction, when compared to the Chang-Hinton neoclassical prediction, exhibits an increasing anomaly with increasing plasma density.

• Research Organization: Massachusetts Inst. of Tech., Cambridge (USA). Plasma Fusion Center
• DOE Contract Number: AC02-78ET51013
• OSTI ID: 6856544
• Report Number(s): DOE/ET/51013-257; PFC/RR-88-14; ON: DE89005034
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700108* -- Fusion Energy-- Plasma Research-- Wave Phenomena
ALCATOR DEVICE
ANTENNAS
BERNSTEIN MODE
CLOSED PLASMA DEVICES
CONFINEMENT TIME
ELECTRICAL EQUIPMENT
ELECTRON DENSITY
ELECTRON TEMPERATURE
EQUIPMENT
HEATING
IMPURITIES
INHOMOGENEOUS PLASMA
INSTABILITY
ION PLASMA WAVES
ION TEMPERATURE
ION WAVES
NONLINEAR PROBLEMS
OSCILLATION MODES
PLASMA
PLASMA DIAGNOSTICS
PLASMA HEATING
PLASMA INSTABILITY
PLASMA WAVES
TEMPERATURE GRADIENTS
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
WAVE PROPAGATION