Hydrogen recycling in HL-1 tokamak

The recycling behaviours and their effects on the particle confinement under various operational conditions in HL-1 device are studied systematically. Using the particle balance equation and a hydrogen recycling model proposed by Howe, the authors estimated the global recycling coefficient R(t) from the data of Hα emission and others. The fueling ratio introduced by Ehrenberg is adopted to analyse the wall pumping and the wall fuelling as the wall/limiter condition or the kinds of inlet gas are altered. The phenomena of particle release after different plasma discharges are also observed and compared by using the quadrupole mass-spectrometer