Studies of impurity confinement injected by laser blow-off in the TJ-1 tokamak

This paper reports studies of particle confinement injected by laser blow-off in the TJ-I tokamak. Injection by laser blow-off of a non-recycling impurity is the most direct and powerful method to measure the particle confinement time in magnetic fusion devices. This technique allowed to obtain an empirical scaling law of particle confinement time in tokamaks. We studied, in a former work, the impurity confinement behaviour with plasma density and toroidal field, but our data did not fit in the former scaling law, what deserves a more complete study. We address in the present work, to extend these studies to different plasma regimes and using a more complete set of diagnostics to document them. The aims of this work are threefold: to study the dependence of particle confinement with plasma current, explore the influence of a polarized limiter on the penetration and confinement of injected impurities at low plasma currents and to assess the performances of a new detector to support impurity injection experiments. (author) 5 refs., 2 figs