Charge separation and target voltages in laser-produced plasmas

Measurement of the voltages of isolated targets irradiated with 50-psec laser pulses show kilovolt target potentials existing for many nanoseconds. The amplitude of the voltage exceeds what is normally expected for a plasma pressure gradient by roughly an order of magnitude. The voltage amplitude and temporal characteristics are found to be dependent on the vacuum chamber dimensions. A simple one-dimensional plasma model explains the voltage characteristics through the existence of space-charge separation effects and leads to a measurement of the plasma temperature.