Oxford Centre for High Energy Density Science (OxCHEDS)

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Recent developments in high pressure physics using laser driven shocks

Inertial Fusion Sciences and Applications 2003 (2004) 897-901

Authors:

M Koenig, E Henry, A Benuzzi-Mounaix, G Huser, B Faral, E Martinolli, S Lepape, P Audebert, T Vinci, D Batani, M Tomasini, B Telaro, B Marchet, I Masclet, M Rabec, C Reverdin, P Loubeyre, T Hall, P Celliers, G Collins, L Dasilva, R Cauble, D Hicks, D Bradley, A MacKinnon, P Patel, J Eggert, J Pasley, O Willi, D Neely, M Motley, C Danson, M Borghesi, L Romagnani, T Boehly, K Lee

Abstract:

High power lasers are nowadays a tool that can be used to determine important parameters in the context of Warm Dense Matter. In this paper, the general issues that have been addressed in the last few years are presented. Recent results concerning water experiments are exposed as a paradigm of laser driven shocks experiments. Finally the first application of proton radiography to the study of shocked material is presented.

Relativistic electron beam transport and characteristics in solid density plasmas

Inertial Fusion Sciences and Applications 2003 (2004) 469-473

Authors:

RA Snavely, F Amiranoff, C Andersen, D Batani, SD Baton, T Cowan, N Fisch, R Freeman, L Gremillet, T Hall, S Hatchett, J Hill, MH Key, J King, J Koch, M Koenig, B Lasinski, B Langdon, A MacKinnon, E Martinolli, P Norreys, P Parks, E Perelli-Cippo, MR Le Gloahec, M Rosenbluth, C Rousseaux, JJ Santos, F Scianitti, M Tabak, R Town, R Stephens

Abstract:

The transport of intense relativistic electron beams in solid density plasma was analyzed. Ponderomotive kinetics modeling code (MPK) for the average relativistic laser-plasma interaction for laser absorption in under-dense or below critical density plasma was proposed. The focused peak intensity of the Petawatt laser system was measured as high as 3.1020W / cm 2. It was found that there was significant lateral electron transport, but of low energy electrons, into the solid.

Stimulated Brillouin scattering from helium-hydrogen plasmas

Inertial Fusion Sciences and Applications 2003 (2004) 280-282

Authors:

DH Froula, L Divol, D Price, R Griffith, G Gregori, EA Williams, SH Glenzer

Abstract:

A study of the stimulated Brillouin scattering (SBS) in helium-hydrogen plasmas has been performed using a gas jet at the Janus Laser Facility. We observe three regions of reflectivity by varying the probe intensity from 1014 to 1016: a saturated region, a linear region, and a region near the threshold for SBS. In the linear regime we find that adding small amounts of hydrogen to a helium plasma reduces the SBS reflectivity by a factor of 4.

Studies of electron transport and isochoric heating and their applicability to fast ignition

Inertial Fusion Sciences and Applications 2003 (2004) 353-358

Authors:

MH Key, F Amiranoff, C Andersen, D Batani, SD Baton, T Cowan, N Fisch, R Freeman, L Gremillet, T Hall, S Hatchett, J Hill, J King, R Kodama, J Koch, M Koenig, B Lasinski, B Langdon, A MacKinnon, E Martinolli, P Norreys, P Parks, E Perelli-Cippo, M Rabec Le Gloahec, M Rosenbluth, C Rousseaux, JJ Santon, F Scianitti, R Snavely, M Tabak, K Tanaka, R Town, T Tsutumi, R Stephens

Abstract:

Experimental measurements of electron transport and isochoric heating in 100 J, 1 ps laser irradiation of solid Al targets are presented. Modeling with a hybrid PIC code is compared with the data and good agreement is obtained using a heuristic model for the electron injection. The relevance for fast ignition is discussed.

TI K-alpha radiography of imploding CU doped CD shells and coned shells

Inertial Fusion Sciences and Applications 2003 (2004) 449-452

Authors:

JA King, RR Freeman, MH Key, K Akli, M Borghesi, R Clarke, T Cowan, H Habara, H Heathcote, S Karsch, R Kodama, K Lancaster, A MacKinnon, C Murphy, P Norreys, P Patel, L Romagnani, R Snavely, R Stephens, C Stoeckl, Y Toyama, M Zepf, B Zhang

Abstract:

The Vulcan laser at the Rutherford Appleton Laboratory in England has been used to show, for the first time, that picosecond laser generated non-thermal K-alpha radiation can be used effectively as a backlighter for radiographic imaging of an implosion. This novel method of x-ray radiography features high temporal resolution, high signal to noise ratio and monochromatic imaging. We present here the Ti K-alpha backlit images of a series of six-beam driven spherical implosions of thin-walled 500 micron Cu doped CD shells. These images, separated by ∼ 0.5ns intervals, capture various states of implosion in and around a stagnation time observed to be ∼ 3.25 ns. Images of imploding coned Cu doped CD shells used in fast ignition research are additionally presented. These images, taken near the previously determined stagnation time, show an imploded core collapsed around an attached gold laser entry cone. These radiographic results were linked to a study of fast electron transport within imploded Cu doped coned CD shells as a result of interaction with a high intensity, short pulse laser. The radiographic results, then, served as a verification of a smooth and uniform implosion and provided an empirical determination of stagnation time, both prerequisites for the electron transport diagnosis.