Experimental Simulation of the Gaseous Tokamak Divertor

The first experimental simulation of the tokamak divertor using a gaseous collector is presented. Significant results are as follows: (i) neutral gas at a pressure of a few militorr is sufficient to absorb the entire localized flux of plasma thermal energy and redistribute it over a wide area, (ii) elastic ion-neutral collisions constitute the main energy-absorbing process (at $T_{e,i}\lesssim 5$ eV), and (iii) a large pressure difference between divertor and main plasma chamber is maintained by plasma pumping in the connecting channel.