Particle exhaust with a vented pump limiter on tore supra

Experiments performed with the Tore Supra vented pump limiter (Vented-PL) demonstrate that a vented structure exhibits a significant particle exhaust capability while allowing moderate heat flux density on the whole head surface. An experimental comparison is presented between a classical pump limiter with throats (Throat-PL) and the test Vented-PL for both deuterium and helium ohmic discharges. It is shown that, without active pumping, the deuterium and helium pressures in the Vented-PL plenum are typically 3 times lower than those measured in the Throat-PL plenum. However, when pumping is activated, this pressure is demonstrated to be high enough to allow the Vented-PL to control actively the plasma density. With only one modular Vented-PL, an exhaust efficiency (defined as the global recycling coefficient reduction) as high as 6% has already been measured for a deuterium plasma.