Development of an advanced experimental system for fundamental investigations of glow and arcing discharge (GADX)

Despite the recent research efforts on the steady-state and pulsed modes of glow discharge, the behavior of the glow discharge below sub-microsecond time scale in DC steady-state and the pulsed mode are still very poorly understood. Pulsed glow discharge has been recently introduced as a technique for preionizing a working gas to form an initial plasma in a coaxial plasma gun developed for Plasma-Jet Magneto-Inerital Fusion (PJMIF). In particular, the initiation of the electron avalanche and its evolution, the onset and the nonlinear evolution of instabilities and chaos, and their self-organization behavior in pulsed glow discharges still provide ample research opportunities. To meet the needs of this research, at Shanghaitech, we are developing a new user experimental facility, named GADX (Glow and Arcing Discharge Experiment), dedicated to fundamental investigations into the behavior of glow discharge in both steady-state and pulsed mode, especially the early phase of the development of the discharge. As the nature of the glow discharge depends to a large extent on the power source that drives it, the system will innovate a stable DC high-voltage current source with very low internal impedance, and output a constant voltage (with stability within 1%~5%). At present, diagnostics include Langmuir probes, survey spectrometers, and Rogowski coils. In the future, diagnostic such as time-resolved laser interference, laser-induced fluorescence, Thomson scattering, high-resolution spectroscopy and online mass spectrometry will be introduced into the system. GADX will also serve as the experimental testbed for the development of these diagnostics for various density and temperature regimes of interest to PJMIF research. In this paper, the conceptual and detailed design of the experimental system will be presented.