PARAMETERS OF THE JET EDGE PLASMA DURING OH, RF AND OPEN BOUNDARY EXPERIMENTS FROM LANGMUIR HEAT FLUX PROBES
Profile measurement of the parameters of the edge plasma have been obtained from an array of 4 heat flux/Langmuir probes extending from a few cm behind the last closed flux surface to the wall. The profiles of electron temperature, density and deposited power show the characteristic logarithmic fall with increased plasma - probe separation. In ohmically heated discharges at a level Ip about 3 MA extrapolation to the plasma edge gives densities of 2-4 x 10**18 m**-3; powers of 2-5 MW m**- 2- and temperatures <= 100 eV. Floating potential measurements show substantial radial electric field. Measurements on discharges with additional RF heating up to 3 MW using different antenna configurations show that in some cases the edge plasma is affected leading to an increase in electron density and temperature, in other cases no change occurs. The formation of an open boundary configuration is marked by a substantial drop in electron density and temperature observed at the probe facing the ion side; the parameters observed at the electron side are unaffected.
Bibliographic Reference: 27TH ANNUAL MEETING OF THE DIVISION OF PLASMA PHYSICS, SAN DIEGO (USA), NOV. 4-8, 1985 PAPER 6P51, PROCEEDINGS P. 1525
Record Number: 1989124129900 / Last updated on: 1987-01-01
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