Quantitative single shot and spatially resolved plasma wakefield diagnostics
University of Oxford (2015)
Abstract:
This dataset and scripts are used in producing the simulations and images in the "Quantitative single shot and spatially resolved plasma wakefield diagnostics" paper. This uses OSIRIS 431 2D.The creation of large-volume, gradient-free warm dense matter with an x-ray free-electron laser
Physics of Plasmas 22:3 (2015)
Abstract:
The efficiency and uniformity of heating induced by hard x-ray free-electron laser pulse is investigated for 0.5 μm silver foils using the X-ray Pump Probe instrument at the Linac Coherent Light Source facility. Intense 8.9 keV x-ray pulses of 60fs duration deposit energy predominantly via inner-shell ionization to create a non-equilibrium Ag solid density plasma. The x-ray pulses are focused to 14 × 17 μm2 by means of beryllium lenses and by varying the total beam energy, the energy deposition is varied over a range of irradiances from 4.4 to 6.5 × 1015 ∼ W/cm2. Two time-and-space resolved interferometers simultaneously probed the expansion of the front and rear sample surfaces and find evidence of a nearly symmetric expansion pointing to the uniformity of energy deposition over the full target thickness. The experimental results are compared with two different hydrodynamic simulations of the sample expansion. The agreement between experimental and theoretical results yields an estimate of the temperature evolution as a function of x-ray irradiance that varies from 8 to 10 eV for the x-ray irradiances studied.Ultrafast electron kinetics in short pulse laser-driven dense hydrogen
Journal of Physics B: Atomic, Molecular and Optical Physics IOP Publishing 48:22 (2015) 224004
Abstract:
Dense cryogenic hydrogen is heated by intense femtosecond infrared laser pulses at intensities of 1015-1016 Wcm-2. Three-dimensional particle-in-cell (PIC) simulations predict that this heating is limited to the skin depth, causing an inhomogeneously heated outer shell with a cold core and two prominent temperatures of about 25 and 40 eV for simulated delay times up to +70 fs after the laser pulse maximum. Experimentally, the time-integrated emitted bremsstrahlung in the spectral range of 8-18 nm was corrected for the wavelength-dependent instrument efficiency. The resulting spectrum cannot be fit with a single temperature bremsstrahlung model, and the best fit is obtained using two temperatures of about 13 and 30 eV. The lower temperatures in the experiment can be explained by missing energy-loss channels in the simulations, as well as the inclusion of hot, non- Maxwellian electrons in the temperature calculation. We resolved the time-scale for laser-heating of hydrogen, and PIC results for laser-matter interaction were successfully tested against the experiment data.
Bromine speciation in hydrous silicate melts at high pressure
Chemical Geology 404, pp 18-26
Abstract:
Target fabrication for the POLAR experiment on the Orion laser facility
High Power Laser Science and Engineering Cambridge University Press (CUP) 3 (2015) e8