Oxford Centre for High Energy Density Science (OxCHEDS): publications

Investigating off-Hugoniot states using multi-layer ring-up targets

Scientific Reports Springer Nature 10:1 (2020) 13172

Authors:

D McGonegle, Pg Heighway, M Sliwa, Ca Bolme, Aj Comley, Le Dresselhaus-Marais, A Higginbotham, Aj Poole, Ee McBride, B Nagler, I Nam, Mh Seaberg, Ba Remington, Re Rudd, Ce Wehrenberg, Js Wark

Abstract:

Laser compression has long been used as a method to study solids at high pressure. This is commonly achieved by sandwiching a sample between two diamond anvils and using a ramped laser pulse to slowly compress the sample, while keeping it cool enough to stay below the melt curve. We demonstrate a different approach, using a multilayer ‘ring-up’ target whereby laser-ablation pressure compresses Pb up to 150 GPa while keeping it solid, over two times as high in pressure than where it would shock melt on the Hugoniot. We find that the efficiency of this approach compares favourably with the commonly used diamond sandwich technique and could be important for new facilities located at XFELs and synchrotrons which often have higher repetition rate, lower energy lasers which limits the achievable pressures that can be reached.

Time-resolved fast turbulent dynamo in a laser plasma

(2020)

Authors:

AFA Bott, P Tzeferacos, L Chen, CAJ Palmer, A Rigby, A Bell, R Bingham, A Birkel, C Graziani, DH Froula, J Katz, M Koenig, MW Kunz, CK Li, J Meinecke, F Miniati, R Petrasso, H-S Park, BA Remington, B Reville, JS Ross, D Ryu, D Ryutov, F Séguin, TG White, AA Schekochihin, DQ Lamb, G Gregori

Nonlinear wakefields and electron injection in cluster plasma

(2020)

Authors:

Marko Mayr, Ben Spiers, Ramy Aboushelbaya, Robert Paddock, James Sadler, Charles Sillett, Robin Wang, Karl Krushelnick, Peter Norreys

Recovery of a high-pressure phase formed under laser-driven compression

Physical Review B American Physical Society (APS) 102:2 (2020) 24101

Authors:

Mg Gorman, D McGonegle, Sj Tracy, Sm Clarke, Ca Bolme, Ae Gleason, Sj Ali, S Hok, Cw Greeff, Pg Heighway, K Hulpach, B Glam, E Galtier, Hj Lee, Js Wark, Jh Eggert, Jk Wicks, Rf Smith

Numerical modelling of chromatic effects on axicon-focused beams used to generate HOFI plasma channels

Journal of Physics: Conference Series IOP Publishing 1596 (2020)

Authors:

Aimee Ross, Aaron Alejo, Alexander von Boetticher, James Cowley, James Holloway, Jakob Jonnerby, Alexander Picksley, Roman Walczak, Simon Hooker

Abstract:

Hydrodynamic optical-field-ionised (HOFI) plasma channels promise a route towards high repetition-rate, metre-scale stages for future laser plasma accelerators. These channels are formed by hydrodynamic expansion of a plasma column produced by optical field ionisation at the focus of a laser, typically from an axicon lens. Since the laser pulses used to generate the initial plasma column are of sub-picosecond duration, chromatic effects in the axicon lens could be important. In this paper we assess these effects using a numerical propagation code. The code is validated using analytical formulae and experimental data. For the parameter range investigated, dispersive effects are found to be of minor importance, reducing the peak on-axis intensity in the focal region by approximately 10%.

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