Study of electron and proton isochoric heating for fast ignition

Abstract

Abstract. Isochoric heating by electrons has been measured in the two limiting cases of small area thin foils with dominant refluxing and cone-long-wire geometry with negligible refluxing in the wire. Imaging of Cu K fluorescence, crystal x-ray spectroscopy of Cu K shell emission, and XUV imaging at 68 eV and 256 eV are discussed. Laser power on target was typically 0.5 PW in 0.7 ps. Heating by focused proton beams generated at the concave inside surface of a hemi-shell and from a sub hemi-shell inside a 30 • cone has been studied with the same diagnostic methods plus imaging of proton induced K . Conversion efficiency to protons has been measured and modeled. Conclusions from the experiments, links to theoretical understanding and relevance to fast ignition are outlined.

Feasibility study of measuring the temperature and pressure of warm dense matter.

“…At intensities of the order of 10 19 W/cm 2 , the laser drives a high current through the sample which heats the target (Figure 1) through Ohmic/resistive losses [4][5][6][7]. Laser-to-electron energy conversion efficiency is ∼10 -1 and the resulting heat deposition can be up to keV at target center down to 100eV at the target edges.…”

“…In proton isochoric heating, TNSA generated protons from the source target (lagging the prompt source x-rays) impinge onto the secondary (sample) target where they absorb throughout the volume ( Figure 2) and heat the sample to the 10 eV scale [6,[10][11][12][13][14]. Those protons are normal to the source rear surface but can be focused with hemi-spherical foils for higher local heating.…”

Effective laser driven proton acceleration from near critical density hydrogen plasma

“…; Snavely et al, 2000;Wilks et al, 2001;Borghesi et al, 2004;Fuchs et al, 2006;Hegelich et al, 2006;Robson et al, 2007) has opened up new areas of research, with applications in radiography (Mackinnon et al, 2006), oncology (Bulanov & Khoroshkov, 2002), astrophysics (Baraffe, 2005), imaging (Fritzler et al, 2003), high-energy-density physics (Dyer et al, 2008), and ion-proton beam fast ignition Key et al, 2006a, b). The fast recent progress has hinted that the extreme parameters of extreme light infrastructure will allow the production of ultra-high-energy ions (GeV and beyond) which will open the door to future unique applications like time and space resolved radiography of dense matter (Borghesi et al, 2010), injectors study for medical applications (Muramatsu and Kitagawa, 2012) for ion beam physics (Hoffmann et al, 2005).…”

Measuring fast electron spectra and laser absorption in relativistic laser-solid interactions using differential bremsstrahlung photon detectors

“…Furthermore, the detailed characterization of the fast electron transport under controlled conditions is important for numerous applications including proton and ion beam production, [6][7][8][9] isochoric heating of high density matter for opacity studies, [10][11][12][13][14] and fast ignition inertial confinement fusion. [15][16][17][18][19][20] Fast electron energy transport is dictated by the resistivity and density of the medium in which the transport is occurring, the fraction of laser energy a) Electronic mail: Robbie.Scott@stfc.ac.uk absorbed into fast electrons, the fast electron source size, their divergence, and energy spectrum.…”