TY - JOUR
T1 - Impurity ion transport studies on the PLT tokamak during neutral-beam injection
AU - Suckewer, S.
AU - Cavallo, A.
AU - Cohen, S.
AU - Daughney, C.
AU - Denne, B.
AU - Hinnov, E.
AU - Hosea, J.
AU - Hulse, R.
AU - Hwang, D.
AU - Schilling, G.
AU - Stratton, B.
AU - Wilson, R.
N1 - Copyright:
Copyright 2016 Elsevier B.V., All rights reserved.
PY - 1984/7
Y1 - 1984/7
N2 - Radial transport of medium- and high-Z ions during co- and counter-neutral-beam heating in the PLT tokamak is studied, using molybdenum and scandium ions as tracer elements. The time evolution of the radial profiles of several ionization stages of both elements, injected by laser blowoff during the neutral-beam heating, is measured under three significantly different beam-plasma combinations. No noticeable differences in the radial profiles attributable to the beam direction are observed. However, a given injected amount resulted in considerably larger interior concentrations of the tracer element in the counter-beam heating cases, suggesting larger penetration of the plasma periphery. Computer simulation with the MIST code suggests a net inward drift of the order 103 cm·s−1 superposed to a diffusion coefficient of the order 104 cm2·s−1 for both scandium and molybdenum ions. Injection of larger amounts of the tracer element, sufficient to cause measurable central electron temperature changes, resulted in dramatic changes in ion-state distributions, making some appear peaked in the centre while others disappeared. This effect could be produced with both co- and counter-beam heating, but with lesser amounts in the latter case. It is interpreted as rearrangement of the ionization balance, rather than any preferential accumulation of the injected element.
AB - Radial transport of medium- and high-Z ions during co- and counter-neutral-beam heating in the PLT tokamak is studied, using molybdenum and scandium ions as tracer elements. The time evolution of the radial profiles of several ionization stages of both elements, injected by laser blowoff during the neutral-beam heating, is measured under three significantly different beam-plasma combinations. No noticeable differences in the radial profiles attributable to the beam direction are observed. However, a given injected amount resulted in considerably larger interior concentrations of the tracer element in the counter-beam heating cases, suggesting larger penetration of the plasma periphery. Computer simulation with the MIST code suggests a net inward drift of the order 103 cm·s−1 superposed to a diffusion coefficient of the order 104 cm2·s−1 for both scandium and molybdenum ions. Injection of larger amounts of the tracer element, sufficient to cause measurable central electron temperature changes, resulted in dramatic changes in ion-state distributions, making some appear peaked in the centre while others disappeared. This effect could be produced with both co- and counter-beam heating, but with lesser amounts in the latter case. It is interpreted as rearrangement of the ionization balance, rather than any preferential accumulation of the injected element.
UR - http://www.scopus.com/inward/record.url?scp=0021453233&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0021453233&partnerID=8YFLogxK
U2 - 10.1088/0029-5515/24/7/001
DO - 10.1088/0029-5515/24/7/001
M3 - Article
AN - SCOPUS:0021453233
SN - 0029-5515
VL - 24
SP - 815
EP - 826
JO - Nuclear Fusion
JF - Nuclear Fusion
IS - 7
ER -