High-energy monoenergetic protons from multistaged acceleration of thin double-layer target by circularly polarized laser

Abstract

Multistaged acceleration of solid-density thin foils by ultraintense circularly polarized laser pulse is investigated. A stable radiation pressure acceleration (RPA) stage is first established. Higher dimensional effects such as transverse instabilities and enhanced electron heating then gradually make the initially opaque foil transparent to the laser light. Accordingly, the dominant acceleration mechanism changes smoothly from RPA to target normal sheath acceleration (TNSA). The transition can therefore enhance the maximum energy of the accelerated ions but broaden their energy spectrum. For a double-layer target, however, the light ions (protons) in the backlayer can be efficiently accelerated in the RPA and TNSA regimes nearly monoenergetically. Two-dimensional particle-in-cell simulations show that with this scheme a circularly polarized laser pulse of peak intensity 3.9×1022 W/cm2 can produce a collimated proton bunch that persists for many Rayleigh lengths and its peak energy can reach 4.2 GeV with FWHM of 200 MeV.

High-charge energetic electron bunch generated by intersecting laser pulses

“…The two pulses are incident symmetrically around the axis y c ¼ 80 lm. The lasers have wavelength k ¼ 1 lm and normalized amplitude a ¼ a 0 expðÀx 2 =ðL=2Þ 2 ÞexpðÀy 2 =ðw=2Þ 2 Þ, 23,24 For h ¼ 0:09 and d ¼ 25 lm, we simulate the interaction of the two laser pulses with the plasma and find that the process can be roughly divided into four stages. Shortly after the injection of the pulses into the plasma, there forms two individual wake bubbles, which accelerate the trapped electrons independently (the electrons are mostly injected at the plasma boundary).…”

Stable laser-ion acceleration in the light sail regime

“…On the other hand, our results demonstrate that the laser pulse contrast has to be controlled carefully, i.e., it has to be assured that the laser intensity does not reach the damage threshold of the target earlier than 1 ps before the arrival of the main laser pulse which is a great challenge for future laser development. Furthermore, the observed stability of the double layer and its high ion densities over a wide range of parameters encourages a staged acceleration scheme using multiple laser pulses in order to enhance the ion energies while maintaining their monochromaticity [36]. …”

Control of laser absorbing efficiency and proton quality by a specific double target

“…For the traditional DL target, the heavy ion foil has an optimal thickness of the order of~l p l a n n 0 c i [28,45]. Here we perform another two simulation groups with the heavy ion layer thickness of l=0.07λ and 0.05λ to test the validity of the SDL target for the different thickness.…”