Experimental study of uniform acceleration with UV laser light

Non-uniformity smoothing and the properties of randomly phase-shifted irradiation with UV lasers (0.27 μm) have been investigated experimentally. Non-uniformity smoothing of the accelerated target measured by X-ray backlighting is in reasonable agreement with the improved 'cloudy day model' in the power density region 5x1013W/cm2 to 2x1014W/cm2 and in the modulation wavelength range 25-70 μm created by multi-spot irradiation. Randomly phase-shifted irradiation, including various modulation wavelengths, has been applied to study non-uniformity smoothing in a wider range of wavelengths by comparing the amplitudes of the Fourier components of UV and green laser intensity distribution and of the X-ray radiation distribution. In the experiments with randomly phase-shifted UV irradiation, local heating of the target has been found by observing the ion energy spectrum, the shock transit time across the target, the burnthrough of the target and the X-ray backlighting shadow. (author). 8 refs, 7 figs