Observations of the Spatial Evolution of a Potential Hump into a Strong Double Layer in a High-Voltage Straight Plasma Discharge

Abstract

The propagation and spatial evolution of a potential hump generated explosively near the cathode were observed in the current-limiting phase of a high-voltage straight discharge with a preexisting hydrogen plasma. Potential profiles along the axis numerically calculated from the real-time $E$ field data demonstrate the evolution of a potential hump into a strong double layer (asymmetric electron hole) with an inverse potential jump ($\frac{e{\ensuremath{\varphi}}_{D}}{k{T}_{e}}\ensuremath{\lesssim}{10}^{3}$) as moving toward the center of the device with a mean velocity (1.2-1.8) \ifmmode\times\else\texttimes\fi{} ${10}^{8}$ cm/sec.