Shielding of energy deposition by ablation of plastics under intense pulsed ion beam irradiation

Abstract

With high power density in solid targets, intense pulsed ion beam with a pulse length of hundreds of ns and cross-sectional energy density of several J/cm2 may induce surface ablation and this effect can be used for thin-film preparation and nanopowder synthesis. Nevertheless, with ablation by the pulsed ion beam, the energy deposition of ions in targets may be affected and this further toughens the analysis of ablation and related material response in applications and ion beam diagnostics. In this study, the energy deposition of nanosecond pulsed ion beam composed of protons and carbon ions on stainless steel and plastics on BIPPAB-450 pulsed ion beam accelerator was investigated with infrared diagnostics. It is revealed that on plastics, under nanosecond IPIB irradiation with energy density of 1.5 J/cm2, ablation plume can be formed at the beginning stage of beam irradiation and the ablation plume may impose strong stopping to the ions in the pulsed ion beam and thus the energy deposition of the ion beam is shielded from reaching the target with over 80% of the beam energy screened. The influence of this energy shielding effect on applications such as beam measurement and material treatment was discussed reasonably.