Efficient laser production of energetic neutral beams

Abstract

Laser-driven ion acceleration by intense, ultra-short, laser pulse has received increasing attention in recent years, and the availability of much compact and versatile ions sources motivates the study of laser-driven sources of energetic neutral atoms. We demonstrate the production of a neutral and directional beam of hydrogen and carbon atoms up to 200 keV per nucleon, with a peak flow of × 2.7 10 13 atom s −1 . Laser accelerated ions are neutralized in a pulsed, supersonic argon jet with tunable density between × 1.5 10 17 cm −3 and × 6 10 18 cm −3 . The neutralization efficiency has been measured by a time-of-flight detector for different argon densities. An optimum is found, for which complete neutralization occurs. The neutralization rate can be explained only at high areal densities (> × 1 10 17 cm −2 ) by single electron charge transfer processes. These results suggest a new perspective for the study of neutral production by laser and open discussion of neutralization at a lower density.

Compact acceleration of energetic neutral atoms using high intensity laser-solid interaction

“…A high energy neutral atom source with the same emittance characteristics seen in ions generating from intense laser-produced plasma 20 , 21 , would seem out of reach of conventional charge transfer methods of neutral atom generation. Charge transfer neutralization of ions accelerated in TNSA by using a gaseous medium is a possibility that has been demonstrated recently 22 . This method uses a separate gaseous cell for neutralization.…”

Optical diagnostics for density measurement in high-quality laser-plasma electron accelerators

“…In fact this method is sensitive to phase gradients of the beam cross-section along two orthogonal directions, and the actual 2D map of the phase is retrieved by analyzing the data with specific software. Finally, the phase shift of interest is calculated by subtracting the phase map of an undisturbed beam acquired in a separate measurement without the sample [33] . It can be considered a single-arm configuration, since interference takes place only at the detector, and is therefore a very robust method allowing for easy installation with a phase sensitivity which is stated to be 2 nm (that is, 30 mrad at 400 nm) [34] .…”

Mass selection in laser-plasma ion accelerator on nanostructured surfaces

“…A high energy neutral atom source with the same emittance characteristics seen in ions generating from intense laser-produced plasma 19,20 would seem out of reach of conventional charge transfer methods of neutral atom generation. Charge transfer neutralization of ions accelerated in TNSA by using a gaseous medium is a possibility that has been demonstrated recently 21 . Instead of using a charge transfer cell for neutralization, if the TNSA accelerated ions could be neutralised in the laser produced plasma itself, then the generation of a beam of energetic neutral atoms with very high current could be achieved.…”