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As part of investigations into on-line wall conditioning for long-pulse tokamaks, reactive gases have been injected into the scrape-off layer (SOL) during a discharge. The first test gas used was trimethylboron (TMB). It is shown that significant amounts of TMB can be puffed during the flat top phase of a discharge without negatively affecting its further evolution. It is also demonstrated that the plasma can be fuelled from the very beginning, including the gas prefill, and maintained exclusively with TMB. Feedback density control is easily achieved. TMB fuelled (puffed) and D(2) fuelled discharges show very similar values of Z(eff), radiated power fraction, and other global parameters. The effective confinement of B and C atoms from TMB is evaluated using spectroscopic signals.

Additional information

Authors: ESSER H G ET AL., Forschungszentrum Jülich GmbH, Institut für Plasmaphysik (DE)
Bibliographic Reference: Article: Journal of Nuclear Materials, Vol. 196-198 (1992) pp. 231-235
Record Number: 199310255 / Last updated on: 1994-11-29
Original language: en
Available languages: en