Proton Shock Acceleration in Laser-Plasma Interactions

Abstract

The formation of strong, high Mach number (2-3), electrostatic shocks by laser pulses incident on overdense plasma slabs is observed in one- and two-dimensional particle-in-cell simulations, for a wide range of intensities, pulse durations, target thicknesses, and densities. The shocks propagate undisturbed across the plasma, accelerating the ions (protons). For a dimensionless field strength parameter a(0)=16 (Ilambda(2) approximately 3 x 10(20) W cm(-2) microm(2), where I is the intensity and lambda the wavelength), and target thicknesses of a few microns, the shock is responsible for the highest energy protons. A plateau in the ion spectrum provides a direct signature for shock acceleration.

Production of high energy protons with hole-boring radiation pressure acceleration

“…[1][2][3][4][5][6][7][8][9] Considerable effort has been put into both the theoretical and, more recently, the experimental aspects 10 of this problem. RPA has been classified into two modes: "hole-boring" 3,[11][12][13][14][15][16] (HB) and "light-sail" (LS). 1,2,6,17 Much attention has been focussed on the light sail mode of RPA because of the favourable scaling that this scheme exhibits.…”

Electromagnetic Field Generation in the Downstream of Electrostatic Shocks Due to Electron Trapping

“…Particles are trapped in the associated electrostatic potential, which steepens and eventually reaches a quasisteady-state collisionless electrostatic shock. Most of the theoretical work dates back to the 1970s [9-13] relying on the pseudo-Sagdeev potential [14] and progress has been mainly triggered by kinetic simulations [15][16][17][18].The short formation time scales and the one dimensionality of the problem make it easily accessible with theory and computer simulations. However, long time shock evolution was often one dimensional or electrostatic codes were used, and the role of electromagnetic modes was mostly neglected.…”

“…Particles are trapped in the associated electrostatic potential, which steepens and eventually reaches a quasisteady-state collisionless electrostatic shock. Most of the theoretical work dates back to the 1970s [9][10][11][12][13] relying on the pseudo-Sagdeev potential [14] and progress has been mainly triggered by kinetic simulations [15][16][17][18].…”

High-quality proton bunch from laser interaction with a gas-filled cone target

“…Depending on the target paraments and laser intensity, ions can be accelerated by several different mechanisms, such as shock acceleration [6,7],light-pressure acceleration [8,[10][11][12], Coulomb explosion [13], target-normal sheath acceleration (TNSA) [14][15][16], etc., as well as their combinations. In TNSA, the energetic electrons produced at the front of a target by the laser ponderomotive force propagate through the target into the backside vacuum can generate a sheath electrostatic field.…”