Ultraviolet probing of laser produced plasmas with picosecond pulses

Technical photography, through such means as interferometry, Faraday rotation, and simple shadowgraphs, can provide significant data for understanding the absorption and transport of energy within laser produced plasmas. For plasmas produced by intense, sub-nanosecond Nd laser pulses, one is required to study electron densities in the 1020 to 1021 e/cc range, with density contour velocities of 106 to 107 cm/sec, and axial scale lengths of 1-20 μm. The relationship between these plasma parameters and the requisite photographic system is described. It is concluded that the system requires a probe wavelength in the middle ultraviolet, a pulse duration in the 10-100 picosecond regime, and large numerical aperture optics corrected for spherical aberrations. Results obtained at 2660 A with holographic microinterferometry, Faraday rotation, and shadowgraphs are presented