Helium exhaust studies with the ALT-II pump limiter in TEXTOR
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=0.7s) as a short pulse of Dt = 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%, and the remaining part seems to be stored in the TEXTOR walls. An estimate of the surface density leads to a value of several times 1.0 E13/cm2. This helium can easily be liberated in subsequent discharges and can be removed efficiently when ALT II is pumping.
Bibliographic Reference: Article: Journal of Nuclear Materials, Vol. 176 & 177 (1990) pp. 816-820
Record Number: 199110876 / Last updated on: 1994-12-02
Original language: en
Available languages: en