Electrostatic probe and optical spectroscopy studies of low temperature laser produced plasmas

Electrostatic probe and optical spectroscopy techniques were used to investigate ion number densities, ion velocities and ion/neutral ratios of laser-produced YBCO plasmas in vacuum and in ambient oxygen. Under appropriate experimental conditions both techniques have been observed to yield consistent values for local ion number densities and velocities in a vacuum environment. Due to confinement of the plume in oxygen ion/neutral ratios were observed to decrease from ∼ 10 in vacuum to ∼ 5 in 60 mTorr of oxygen, at 1.5 cm from the target and 1 μs delay time.