Laser-driven proton acceleration from ultrathin foils is investigated experimentally using F/3 and F/1 focusing. Higher energies achieved with F/3 are shown via simulations to result from self-focusing of the laser light in expanding foils that become relativistically transparent, enhancing the intensity. The increase in proton energy is maximised for an optimum initial target thickness, and thus expansion proﬁle, with no enhancement occurring for targets that remain opaque, or with F/1 focusing to close to the laser wavelength. The effect is shown to depend on the drive laser pulse duration.
|Number of pages||6|
|Journal||Physical Review Research|
|Publication status||Accepted/In press - 7 Sep 2020|
- laser driven proton accelerator
- ultrathin foils
- pulse amplification