Interferometric studies of the electron density dynamics at the periphery of a micropinch discharge

Results are presented from experimental studies of the electron density dynamics at the periphery of a low-inductance vacuum spark. The measurements were performed using a newly developed homodyne quadrature interferometer possessing fairly high dynamic range and performance. The experiments demonstrated the presence of a plasma with an electron density of ne ≥ 1018 cm−3 at the periphery of the discharge gap. The radial electron density distribution was shown to have a pronounced tubular structure. The relatively high values of the peripheral electron density indicate that the process of pinching can be substantially affected by shunt currents flowing at the discharge periphery.