Oxford Centre for High Energy Density Science (OxCHEDS)

Abstract:

We review a recent experimental campaign to study the interaction physics of petawatt laser pulses incident at relativistic intensities on solid targets. The campaign was performed on the 500 J sub-picosecond petawatt laser at the Rutherford Appleton Laboratory. An extensive suite of optical, x-ray, and particle diagnostics was employed to characterise the processes of laser absorption, electron generation and transport, thermal and K-alpha x-ray generation, and proton acceleration.

Abstract:

Neutron time of flight signals have been observed with a high resolution neutron spectrometer using the petawatt arm of the Vulcan laser facility at Rutherford Appleton Laboratory from plastic sandwich targets containing a deuterated layer. The neutron spectra have two elements: a high-energy component generated by beam-fusion reactions and a thermal component around 2.45 MeV. The ion temperatures calculated from the neutron signal width clearly demonstrate a dependence on the front layer thickness and are significantly higher than electron temperatures measured under similar conditions. The ion heating process is intensity dependent and is not observed with laser intensities on target below 1020 W cm-2. The measurements are consistent with an ion instability driven by electron perturbations. © 2005 IOP Publishing Ltd.

Abstract:

We report the observation of monoenergetic electron beams (dE/E < 5%) produced by the interaction of a 12TW, 40fs laser pulse with underdense plasma, in contrast to all previous experiments, which produced energy spreads ∼100%. © 2005 Optical Society of America.