Abstract
In TEXTOR helium removal experiments with the pump-limiter ALT-II have started. To simulate the presence of helium ash in the plasma, helium is injected into the discharge (e.g. at t = 0.7 s) as a short pulse of Δt = 20 ms. It is found that the He is removed from the discharge in an e-folding time of about half a second for neutral beam heated plasmas and in an e-folding time of about 1.5 s in an OH plasma. The exhaust efficiency of helium amounts to about 8% and is close to the one for deuterium. The fuelling efficiency for the injected helium is found to be in the range of 50-100%; the remaining part seems to be stored in the TEXTOR walls. An estimate of the surface density leads to a value of several times 1013 cm-2. This helium can easily be liberated in succeeding discharges and can be removed efficiently when ALT is pumping.
Original language | English |
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Pages (from-to) | 816-820 |
Number of pages | 5 |
Journal | Journal of Nuclear Materials |
Volume | 176-177 |
Issue number | C |
DOIs | |
State | Published - Dec 3 1990 |
Funding
We wish to express our gratitude to the TEXTOR, NI and ALT groups, in particular to B. Giesen, P. Hiittemann, M. Lochter and M. Korten (TEXTOR operation). We especially appreciate the able technical assistanceo f B. Hiller. This work is partly supported by the US Department of Energy.