Comment on 'Collimated Multi-MeV Ion Beams from High-Intensity Laser Interactions with Underdense Plasma'

摘要

In a Letter [1], L. Willingale et al. reported on the detection of a collimated He~(2+) ion beam accelerated up to 40 MeV by petawatt-class laser from a gas jet target. The ion acceleration is explained in terms of longitudinal electric field located in the expanding sheath front formed by electrons expelled by the laser pulse. A conclusion was made that gas targets may be useful for generating collimated beams of high-energy ions from laser-plasma interactions, as suggested also in [2].