AN INJECTOR AMPLIFIER DOUBLE TARGET CONFIGURATION FOR THE NE-LIKE GE X-RAY LASER SCHEME

The XUV lasing output from one germanium slab target has been efficiently coupled into, and further amplified in, a second plasma produced by irradiation of a similar target from the opposite direction. The operation of such a double target was shown to be strongly dependent on the distance by which the two target surfaces were displaced. The line brightness peaked for a surface displacement of approximately 200-mu-m and it was observed that the pointing direction of one output beam could be controlled by the surface separation in an asymmetric geometry. Gain length products of approximately 16 with estimated output powers close to the megawatt level were achieved on both the 23.2 and 23.6 nm J=2-1 transitions for an optimised target configuration. Maximum effective coupling efficiencies of the individual outputs from double targets, comprising 2.2 and 1.4 cm length components, approached 100% for beams propagating from the shorter to the longer target.

Diagnostic of laser contrast using target reflectivity

Using three different laser systems, we demonstrate a convenient and simple plasma based diagnostic of the contrast of high-power short-pulse lasers. The technique is based on measuring the specular reflectivity from a solid target. The reflectivity remains high even at relativistic intensities above 10(19) W/cm(2) in the case of a high-contrast prepulse-free laser. On the contrary, the specular reflectivity drops with increasing intensities in the case of systems with insufficient contrast due to beam breakup and increased absorption caused by preplasma.

Target charging effects on proton acceleration during high-intensity short-pulse laser-solid interactions

We report results from experiments performed at the Rutherford Appleton Laboratory using the VULCAN laser facility (I>5x10(19) W cm(-2)). Single wire targets were used, and on some shots additional objects were placed near the target. These were positioned so that they were not irradiated by the laser. Proton emission from single wire targets was observed as radially symmetric structures (

Imaging of high harmonic radiation emitted during the interaction of a 20 TW laser with a solid target

We present images of the source of extreme ultraviolet (XUV) harmonic emission at a wavelength of 220 Angstrom from the interaction of a 20 TW, 1.053 mu m Nd:glass laser beam focused to intensities up to 4x10(18) W cm(-2) onto a solid target. From these measurements we determine an upper limit to the source size and brightness of the harmonic emission to show its efficacy as a novel source of short-pulse, coherent XUV radiation. We also demonstrate the empirical scaling of the harmonic generation efficiency with irradiance up to 10(19) W mu m(2) cm(-2), and extrapolate to estimate the possible source brightness at higher irradiances. These source brightnesses are compared to those available from an x-ray laser system. (C) 1997 American Institute of Physics.