Tokamak edge plasma investigation by laser blow-off

Edge plasma density vs plasma radius plots of the MT-1 tokamak plasma was measured by a new laser blow-off technique. This sodium films evaporated onto a glass substrate were blown off by a Q-switched ruby laser pulse. The enhanced shortening of the pulse of neutrals was observed along the beam propagating toward the plasma centre by measuring the resonance light intensity of atoms excited by plasma electrons. The transport of sodium atoms injected into the plasma and that of the intrinsic impurities was investigated. The measurement of the intensity of the impurity atomic line is used for the determination of the impurity containment time. (R.P.) 21 refs.; 8 figs