Coupling of an exploding plasma to a magnetized ambient plasma measured with LIF*

The coupling of plasma jets to ambient media near young stellar objects, Herbig-Haro objects, and supernova remnants is of considerable interest to the astrophysical community. In this work, we study the interaction of a laboratory scale jet formed by a carbon laser-produced plasma (LPP) with the ions of a magnetized argon background plasma ($n_{jet} /n_{Ar} <30$,$\mbox{v}_{\mbox{jet}} \mbox{/c}_{\mbox{s}} =20$,$\mbox{v}_{\mbox{jet}} \mbox{/v}_{\mbox{A}} \le \mbox{1})$ using laser-induced fluorescence (LIF). The excitation light was provided by a planar beam of a pulsed dye laser which, by tuning to the Doppler-broadened 611.5 nm absorption line, sampled the distribution function of metastable Ar-II separating the background from the components of the jet. A fast shutter ($\ge 3$ ns) CCD camera captured the 461 nm fluorescence with 40 ns time and .6 mm$^{2}$ spatial resolutions. The distribution functions obtained from the LIF diagnostic reveal significant density enhancement and a subsonic parallel drift localized at the LPP-ambient interface. Within the jet region, the background ion signal indicates the formation of a density void and suggests a lateral snow-plow effect. To our knowledge, this is the first LIF measurement of a supersonic jet coupling to an ambient plasma. Supplemental Langmuir probe measurements characterize the jet's dimensions and dependence on magnetic field strength and background ion mass up to 6 meters from the LPP source.