Transport of wall released metal impurities in the scrape-off layer of a tokamak

Cold neutral impurities of low concentration penetrate into the s.o.l. plasma and are ionized by electron impact. Once ionized, the impurities suffer Coulomb collisions with the hydrogen ions of the s.o.l. plasma streaming onto a neutralizing limiter (or into a divertor). The impurity ions are further ionized, heated, and swept along the magnetic field due to friction forces exerted by the hydrogen ions (and by electric field acceleration). Simultaneously, the radial drift is enhanced. (orig./AH)