Oxford Centre for High Energy Density Science (OxCHEDS)

Abstract:

A hydrogen plasma waveguide for high-intensity laser pulses is described. The guiding channel is formed by a small-scale discharge in a hydrogen-filled capillary. The measured lifetime of the capillary is inferred to be greater than 106 shots. The results of interferometric measurements of the electron density in the capillary are presented. The guiding channel is found to be highly ionized with an axial electron density of 2.7 ×1018 cm-3, and parabolic, the curvature corresponding to a matched spot-size of 37.5 μm. ©2000 The American Physical Society.

Abstract:

We present measurements of the electron density profile in the guiding channel of a novel plasma waveguide. The results of experiments to demonstrate guiding at peak intensities of >10−17 W cm−2 will be presented.

Abstract:

Nuclear activation has been observed in materials exposed to the ablated plasma generated from high intensity laser-solid interactions (at focused intensities up to 2 × 10¹⁹ W/cm²) and is produced by protons having energies up to 30 MeV. The energy spectrum of the protons is determined from these activation measurements and is found to be consistent with other ion diagnostics. The possible development of this technique for "table-top" production of radionuclides for medical applications is also discussed.

Abstract:

Time-resolved x-ray diffraction experiments are presented showing ultrafast modulation of anomalous transmission and recurrence of Pendellosung oscillations in thick crystals. These results are discussed in the context of coherent control and femtosecond x-ray pulse generation.