PROBE MEASUREMENTS OF THE DENSITY AND TEMPERATURE PROFILES IN THE JET PLASMA BOUNDARY
Measurements of the boundary plasma parameters have been made over a range of conditions in ohmic discharges. Measurements have been made to within 30-44 mm of the nominal plasma edge determined by a calculation of the last closed field line. (The plasma parameters decayed exponentially from this point right out to the wall at a distance of typically 350 mm. The e-folding lengths for the density were in the range 30-60 mm, for the temperature 40-300 mm, and for the power about 30 mm.) From the particle fluxes and energies estimates have been made of the expected impurity production rate. The measured plasma parameters have enabled calculations of the ionization rate of impurities from the wall to be made. The attenuation of the flux from the wall and the ionization source function have been calculated for carbon, oxygen and nickel. Analysis of the behaviour of the impurities from the limiter is difficult because it is unreliable to extrapolate the boundary data beyond the limiter edge. A first approximation to the source function can be obtained by using constant values of n-e(a) and T-e(a).
Bibliographic Reference: WRITE TO THE PUBLICATIONS OFFICER, JET JOINT UNDERTAKING, ABINGDON, OXON, OX14 3EA (UK) MENTIONING REPORT JET-P(86)07, 1986
Record Number: 1989125010100 / Last updated on: 1987-01-01
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