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Atomic and Laser Physics
Credit: Jack Hobhouse

Professor Steven Rose

Visiting Professor

Research theme

  • Lasers and high energy density science

Sub department

  • Atomic and Laser Physics

Research groups

  • Oxford Centre for High Energy Density Science (OxCHEDS)
Steven.Rose@physics.ox.ac.uk
Imperial College London webpage
  • About
  • Publications

High-temperature limit of Breit-Wheeler pair production in a black-body field

Results in Physics Elsevier 41 (2022) 105917

Authors:

Jj Beesley, Sj Rose

Abstract:

This paper presents an analytic expression for the high-temperature limit of Breit–Wheeler pair production in a black-body field to lowest order in perturbation theory, of interest in early-universe cosmology. The limit is found to be a good approximation for temperatures above about three times the electron rest energy. It is also found that coupling to low-energy processes remains important at arbitrarily high temperatures, due to the exchange of a low-energy virtual fermion near the mass shell. This appears mathematically in the rate as a logarithmic factor of the photon temperature divided by the electron rest mass.
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L-Shell X-ray conversion yields for laser-irradiated tin and silver foils

Laser and Particle Beams Hindawi 2022 (2022) 3234804

Authors:

Rl Singh, S White, M Charlwood, Fp Keenan, C Hyland, D Bailie, T Audet, G Sarri, Sj Rose, J Morton, C Baird, C Spindloe, D Riley

Abstract:

We have employed the VULCAN laser facility to generate a laser plasma X-ray source for use in photoionization experiments. A nanosecond laser pulse with an intensity of order 1015 Wcm−2 was used to irradiate thin Ag or Sn foil targets coated onto a parylene substrate, and the L-shell emission in the 3.3–4.4 keV range was recorded for both the laser-irradiated and nonirradiated sides. Both the experimental and simulation results show higher laser to X-ray conversion yields for Ag compared with Sn, with our simulations indicating yields approximately a factor of two higher than those found in the experiments. Although detailed angular data were not available experimentally, the simulations indicate that the emission is quite isotropic on the laser-irradiated side but shows close to a cosine variation on the nonirradiated side of the target as seen experimentally in the previous work.
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An Experimental Study of Magnetic Flux Penetration in Radiatively Driven Plasma Flows

Institute of Electrical and Electronics Engineers (IEEE) 00 (2022) 1-1

Authors:

JWD Halliday, A Crilly, J Chittenden, S Merlini, S Rose, D Russell, LG Suttle, RC Mancini, V Valenzuela-Villaseca, SN Bland, SV Lebedev
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Investigating radiatively driven, magnetized plasmas with a university scale pulsed-power generator

Physics of Plasmas AIP Publishing 29:4 (2022) 042107

Authors:

Jack WD Halliday, Aidan Crilly, Jeremy Chittenden, Roberto C Mancini, Stefano Merlini, Steven Rose, Danny R Russell, Lee G Suttle, Vicente Valenzuela-Villaseca, Simon N Bland, Sergey V Lebedev

Abstract:

We present first results from a novel experimental platform that is able to access physics relevant to topics including indirect-drive magnetized inertial confinement fusion, laser energy deposition, various topics in atomic physics, and laboratory astrophysics (for example, the penetration of B-fields into high energy density plasmas). This platform uses the x rays from a wire array Z-pinch to irradiate a silicon target, producing an outflow of ablated plasma. The ablated plasma expands into ambient, dynamically significant B-fields (∼5 T), which are supported by the current flowing through the Z-pinch. The outflows have a well-defined (quasi-1D) morphology, enabling the study of fundamental processes typically only available in more complex, integrated schemes. Experiments were fielded on the MAGPIE pulsed-power generator (1.4 MA, 240 ns rise time). On this machine, a wire array Z-pinch produces an x-ray pulse carrying a total energy of ∼15 kJ over ∼30 ns. This equates to an average brightness temperature of around 10 eV on-target.
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Multi-group radiation diffusion convergence in low-density foam experiments

Journal of Quantitative Spectroscopy and Radiative Transfer Elsevier 280 (2022) 108070

Authors:

Kw McLean, Steven Rose

Abstract:

We present an in-depth analysis of a Marshak radiation wave moving through an iron-oxide (Fe2O3) foam using a 1D multigroup diffusive radiation transport model, MDART (Multigroup Diffusion Algorithm for Radiation Transport). We consider the consequences of under-resolving the group structure and address how this could lead to incorrect conclusions in the analysis of general supersonic radiation wave experiments. We also provide an analysis of the types of experimental outcome one may incorrectly link to physical effects but are in fact due to poor simulation practice.

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