Particle, in particular helium removal experiments optimized by the dynamic ergodic divertor

The pump limiter is one of the few schemes for particle removal from and density control in a tokamak. An exhaust efficiency of 2–10% has been reached depending on the plasma parameters. In a burning steady state reactor, helium has to be removed in a time scale of <15 energy confinement times for clean plasmas. This goal has barely been reached with the pump limiter on TEXTOR. The widening of the scrape off layer with the dynamic ergodic divertor (DED) promises an increase of the removal rate by nearly a factor of 2.