Helium compression and enrichment with poloidal divertor

The helium ash enrichment function of a divertor has been experimentally demonstrated. Helium atoms accumulate in the divertor region, as the electron density of main plasma increases. With a helium allowance of 1% of electron density in the main plasma, neutral helium at the divertor region is as high as 3.6 x 10-5 Torr. A factor of 2.4 helium enrichment in the divertor region was also observed. This experiment indicates the possibility of helium ash exhaust in an alpha-heated, diverted tokamak using practical-sized pumping ducts. (author)