Generating High-Current Monoenergetic Proton Beams by a CircularlyPolarized Laser Pulse in the Phase-StableAcceleration Regime

Abstract

A new ion acceleration method, namely, phase-stable acceleration, using circularly-polarized laser pulses is proposed. When the initial target density n(0) and thickness D satisfy a(L) approximately (n(0)/n(c))D/lambda(L) and D>l(s) with a(L), lambda(L), l(s), and n(c) the normalized laser amplitude, the laser wavelength in vacuum, the plasma skin depth, and the critical density of the incident laser pulse, respectively, a quasiequilibrium for the electrons is established by the light pressure and the space charge electrostatic field at the interacting front of the laser pulse. The ions within the skin depth of the laser pulse are synchronously accelerated and bunched by the electrostatic field, and thereby a high-intensity monoenergetic proton beam can be generated. The proton dynamics is investigated analytically and the results are verified by one- and two-dimensional particle-in-cell simulations.

Stable laser-produced quasimonoenergetic proton beams from interactive laser and target shaping

“…The RPA scheme is supposed to have the potential to produce even GeV proton beams [30][31][32][33][34][35][36][37][38][39][40][41][42]. Often ultrathin target of tens or hundreds of nanometers along with circularly polarized laser pulses are adopted in order to produce quasimonoenergetic proton beams, even though a linearly polarized laser pulse may also work out in some parameter range [43].…”

“…Thus the hole-boring stage is almost skipped and the plasma sheath layer is immediately pushed away from its original position. Afterwards, it is steadily accelerated as a whole for a long time [31]. Qiao et al proposed the ''relativistic hole-boring'' regime [38], which requires that the laser intensity to be as high as to satisfy I L % 0:25m i n i c 3 so that the hole-boring velocity approaches the speed of light, realizing smooth connection between the short hole-boring stage and light sail stage.…”

“…Qiao et al proposed the ''relativistic hole-boring'' regime [38], which requires that the laser intensity to be as high as to satisfy I L % 0:25m i n i c 3 so that the hole-boring velocity approaches the speed of light, realizing smooth connection between the short hole-boring stage and light sail stage. Theoretically, the optimal target thickness is D opt ¼ a=ðnÞ [31,34], where D opt is normalized by the laser wavelength in vacuum 0 , a is the laser amplitude normalized by m e ! 0 c=e, and n is the target density normalized by the critical density n c .…”

Sub-TeV proton beam generation by ultra-intense laser irradiation of foil-and-gas target

“…6 Existing studies have shown that proton beams at the GeV level can be obtained by radiation pressure acceleration (RPA) using > 10 22 W/cm 2 lasers. [7][8][9][10][11][12] In that scheme the light pressure in the plasma is balanced by the charge-separation field, so that the electron and proton layers co-move as a double-layer. [13][14][15][16][17][18][19][20] However, because of instability the acceleration length is limited to less than hundreds of micrometers and it is difficult to increase the ion energy.…”

Large-scale proton radiography with micrometer spatial resolution using femtosecond petawatt laser system

“…Further, these energetic ion beams have potential applications in fast ignition for inertial confinement fusion, 4 medical therapy, 5 proton imaging, 6 and so on. MeV−GeV protons may be obtained through different mechanisms, 7 such as target normal sheath acceleration (TNSA), [8][9][10][11][12][13][14] radiation pressure acceleration (RPA), [15][16][17][18][19][20][21][22] collision-less shock acceleration, [23][24][25][26][27] breakout afterburner (BOA) laser acceleration, 28 and so on. Of these mechanisms, TNSA may be the most feasible for experimental application.…”