Measurements of particle confinement in tokamaks.

Abstract

Experimental measurements on particle confinement in tokamaks are reviewed. The global particle confinement is mainly determined by recycling particle flux at the edge, which can be evaluated from Hαemission. The global particle confinement time scales with the line averaged electron density in small tokamaks, while it decrease with electron density in large tokamaks since particle recycling is more localized at the edge. The particle confinement appears to be degrade with heating power similarly to the energy confinement. Particle transport both in the main plasma and in the scrape-off layer is also discussed.