Characterization of a high-density large scale pulsed gas jet for laser-gas interaction experiments

We present the characteristics of a high-density pulsed gas jet developed t o study the interaction of a short-pulse, high-intensity laser with a large scale underdense plasma. The jet was characterized by laser interferometry . Measurements of density profile were performed for a 5 mm diam cylindrica l nozzle and for a 20x1 mm slit. In this latter case, a systematic study of the output density as a function of the backing pressure and of the valve opening duration is presented. At 1 mm from its outlet, the cylindrical noz zle provides densities up to 6.9x10(19) cm(-3) for an 8 bar backing pressur e with a 3 mm full width at half maximum Gaussian-shaped profile. Under the same conditions, the slit produces a 20 mm long flat-top profile with a ma ximum density of 2.1 x10(19) cm(-3). (C) 1999 American Institute of Physics . [S0034-6748(99)02405-3].