Experimental investigation of non-thermal electric fields and plasma waves in pulsed-power plasmas

Summary form only given. The evolution of electric fields in pulsed current-carrying plasmas is an intriguing problem in plasma physics. It is of high importance for studying mechanisms of B-field-plasma interaction, particle acceleration, growth of instabilities and plasma waves. As yet, to the best of our knowledge, attempts to observe electric fields in such plasmas suffered from various difficulties. In this report we describe a novel application of laser-spectroscopy to investigate the electric fields and the properties of plasmas under high-power pulses at the nanosecond time scale. The method is based on resonant laser-pumping combined with electron excitations and de-excitations by the plasma electrons, which allows for simultaneous observations of various line intensities, due to both allowed and forbidden transitions. These observations, together with novel line-shape calculations recently developed, allow for obtaining the electron density, electron temperature, and electric fields. The study is carried out in a coaxial-pulsed-plasma configuration. The plasma is doped with a laser-produced lithium beam, followed by pumping of a selected transition of LiI using a tunable dye laser. Here we present recent results and analysis of the electric field structure in the plasma (n=3/spl times/10/sup 14/ cm/sup -3/) under the application of a current /spl ap/200 kA. We believe that these measurements yielded for the first time the evolution of the electric field generated by currents in the plasma with a nanosecond temporal resolution and a sub-millimeter spatial resolution.