Plasma formation and electrical breakdown in water

Summary form only given. The temporal development of plasma formation in water with up to MV/cm pulsed electric fields applied was explored in a strongly inhomogeneous (wire-plane), and a semi-homogeneous (sphere-plane) electric field configuration. In the first case, by applying 120 kV voltage pulses to a tungsten wire with a diameter of 75 pm, and the second, plane electrode being 23 mm apart, an electric field of more than 2 MV/cm was generated at the wire surface. Replacing the wire with a 1.5 mm diameter sphere allowed us to study electrical breakdown in water in a quasihomogeneous electric field configuration. With submillimeter gaps and voltages of up to 30 kV, electric fields of up to MV/cm could be generated in this case. High-speed photography and an interferometric method were used to explore the temporal development of the discharges. The temporal resolution was, determined by a high-speed camera, on the order of one nanosecond.