ALP Seminar: Laser-acceleration of energetic protons and fast ignition inertial confinement fusion

Ion acceleration by a high intensity (> 1018 W/cm2 ) laser pulse interacting with a solid target has been an active research area [1]. The major interest stems from its use as a diagnostic tool in high energy density science [2] and its applications in inertial confinement fusion [3] and warm dense matter generation. We have carried out a series of experiments from mid-scale laser facilities — with energies 10-100s of joules and pulse lengths 10-100s of femtoseconds — to large scale facilities where energies exceed 1 kilojoule and pulse lengths vary between 1-10s of picoseconds. These experiments show that the proton energy scaling and conversion efficiency significantly varies with both laser energy and pulse length. Even with modest laser intensities of 1017- 1018 W/cm2 , the proton energies may significantly exceed those resulting from pondermotive scaling [4]. Experimental data in conjunction with PIC modeling has helped to unravel new phenomena. These results have brought us closer to meeting some of the requirements (energy, spectrum and beam size) for proton fast ignition. However, some physics challenges still need to be addressed. A review of past and current work will be presented.

[1] A. P. Fews et al., Phys. Rev. Lett. 73, 1801-1804 (1994); R. A. Snavely et al., Phys. Rev. Lett. 85, 2945 (2000); J. Fuchs et al., Nat. Phys. 2, 48 (2006); A. Macchi et al., Rev. Mod. Phys. 85, 751 (2013).

[2] J. R. Rygg et al., Science 319, 1223 (2008).

[3] M. Roth et al., Phys. Rev. Lett. 86, 436–439 (2001).

[4] J. Kim et al., Phys. Plasmas 25, 083109 (2018)

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