Laser amplification by Stimulated Brillouin Backscattering

Plasmas, by exciting ion acoustic waves (Stimulated Brillouin Scattering), can be used to transfer energy from moderately long, high-energy laser pulses to short ones. The topic was investigated in collaboration with the SPRINT team and the University of Roma.

1D and 2D PIC simulations in the strong coupling regime (for low plasma temperatures and high laser intensities) were performed; they showed large amplification factors (above 100) and pump depletion. A first experiment was conducted on ELFIE in an Argon plasma (at 1020 cm-3) to confirm these predictions. A total energy transfer of ~50 mJ was measured which corresponds almost to the maximum available energy for the given experimental set-up. Optimization of the process is ongoing; lower plasma densities (to improve the pump quality) and short seed (to allow compression to higher – even relativistic - intensities) are considered. The possibility of reaching a new regime, where Stimulated Brillouin and Raman Scattering are replaced by a hybrid instability, was also exhibited.

Relevant publications

- L. Lancia et al., Phys. Rev. Lett. 104, 025001 (2010)
- S. Weber et al., Phys. Rev. Lett. 111, 055004 (2013)