Description
Laser-driven ion acceleration offers a compact alternative to conventional accelerator technology for medical applications, particularly carbon-ion radiotherapy, where high linear energy transfer and enhanced relative biological effectiveness are key advantages in treating radio-resistant tumours. Recent advances in multi-petawatt laser systems enable exploration of advanced acceleration regimes capable of accelerating heavy ions to high energies with enhanced beam qualities.
We report on experimental results from the Apollon 3-PW laser facility demonstrating the generation of high-energy carbon ion beams from ultrathin amorphous carbon foils irradiated at intensities of ~10²² W cm⁻². By operating in a hybrid regime of relativistically induced transparency and radiation pressure acceleration, we are able to achieve transparency-enhanced acceleration. An optimum target thickness of ~180 nm was identified, producing carbon ions with energies exceeding 55 MeV per nucleon (660 MeV), which is among the highest reported in the literature, with the highest energies and flux observed along the laser axis.
The observed spectral modulations and thickness dependence are characteristic of advanced acceleration regimes beyond the conventional target normal sheath acceleration. Two-dimensional particle-in-cell simulations performed under experimentally relevant conditions reproduce the key features of the data and highlight the critical role of laser temporal contrast and pre-plasma formation in controlling the acceleration dynamics.
These results represent an important step toward laser-driven carbon-ion sources suitable for medical research, demonstrating scalable heavy-ion acceleration at multi-petawatt facilities. The findings are directly relevant to the development of future laser-based carbon-ion platforms at ELI Beamlines for radiobiology studies.
