Effect of preionization on the implosion dynamics of single and double argon gas puffs

Experiments on the implosion of both single and double argon gas puffs were carried out in the IMRI-4 (t_fr = 1.1 μs and I_m = 350 kA) and GIT-4 (t_fr = 0.12 μs and I_m = 1.7 MA) current generators. Three different sources of gas-puff preionization were used: (i) UV spark radiation, (ii) a cylindrical magnetron discharge in the crossed E × B fields, and (iii) a planar magnetron discharge in the crossed E × B fields. With the use of an optical streak camera, for all three methods of preionization, conditions are found under which the stratification of the current sheet occurs during the implosion of the gas puff. Experimental data show that the dynamics of the gas-puff implosion depends on the preionization method. The use of magnetron preionization results in suppression of the instabilities excited during the gas-puff implosion and allows the obtaining of stable plasma parameters in the final stage of implosion. It is shown that, in a single gas puff, a plasma column with an initial radius of 30 mm can be uniformly compressed to a stable plasma cylinder with a radius less than 2 mm.