Ion Acceleration in Multispecies Targets Driven by Intense Laser Radiation Pressure

Abstract

The acceleration of ions from ultra-thin foils has been investigated using 250 TW, sub-ps laser pulses, focused on target at intensities up to 3×10 20 W cm −2 . The ion spectra show the appearance of narrow band features for proton and Carbon peaked at higher energy (in the 5-10 MeV/nucleon range) and with significantly higher flux than previously reported. The spectral features, and their scaling with laser and target parameters, provide evidence of a multispecies scenario of Radiation Pressure Acceleration in the Light Sail mode, as confirmed by analytical estimates and 2D Particle In Cell simulations. The scaling indicates that monoenergetic peaks with more than 100 MeV/nucleon energies are obtainable with moderate improvements of the target and laser characteristics, which are within reach of ongoing technical developments.

Laser-ion accelerators: State-of-the-art and scaling laws

“…As shown in the Fig. 4(d), the experimental data agrees well with the ion energy estimated by a simple rigid model for RPA-LS mechanism [18,19]. As expected for the non-relativistic case, the ion energy is seen to scale as (a 0 2τ p /χ) 2 .…”

“…the BOA mechanism mentioned earlier). The RPA-LS scheme for ion acceleration was extensively studied in a recent experiment carried out employing the PW arm of the VULCAN laser system at the Rutherford Appleton Laboratory, STFC, UK [18]. The laser delivered ∼ 200 J energy on target in sub-ps pulses, focused on target at normal incidence by an f/3 off axis parabolic mirror, reaching peak intensity ~ 3 × 10 20 W/cm 2 .…”

Experimental demonstration of a compact epithermal neutron source based on a high power laser

“…The input flux of fast neutrons can be significantly enhanced by increasing the energy and number of incident ions on the catcher. Order of magnitude higher fast neutron fluxes than produced in the current experiment have been already reported [2][3][4], and, in principle, can be further improved upon by taking advantage of ongoing developments in laser-driven ion acceleration [23][24][25]. A credible source of fast neutrons can also be obtained by deploying MeV electron jets from laser-driven exploding foils [5].…”

An automated, 0.5 Hz nano-foil target positioning system for intense laser plasma experiments

“…Experiments, currently exploiting micrometer foil targets for target normal sheath acceleration (TNSA) [6] , provide a world record of maximum proton energy beyond 85 MeV [7] . With nm thin foils, novel acceleration mechanisms such as radiation pressure acceleration (RPA) [8][9][10][11][12][13][14] and breakout afterburner (BOA) [15,16] have already demonstrated a higher conversion efficiency and faster energy scaling which are in favor for potential applications [17] .…”