Reflected light and harmonic generation from thin foils as a diagnostic for laser-driven ion acceleration experiments

Recent developments in laser driven ion acceleration show its potential as an attractive alternative to conventional accelerators for promising applications. In order to further develop and achieve better control over these sources, clear understanding of the physics behind the extreme laser-matter interaction is fundamental.  

Our group has recently reported an increase of proton energies when manipulating the spectral phase of the driving laser pulse [1]. While the effect has been observed repeatedly over several experiments, further studies and experimental observables are required to benchmark simulations and study changes in plasma dynamics that lead to higher particle energies when using certain phase conditions.

Reflected laser light and harmonics coming from the critical density surface are ideal diagnostics to study electron dynamics and energy coupling between the laser and plasma [2]. In this work, we focus on spectral modulations on reflected light and harmonics when manipulating the spectral phase of the pulse during laser driven ion acceleration experiments with the DRACO laser (30 fs, 5×10²¹ W/cm²). We study possible reasons for these changes, comparing with previous experiments and simulations [3], and explore the potential of the effect to study the impact of varying laser compression on particle acceleration.   

   

[1] Ziegler, T. et al. Sci Rep 11 (2021)

[2] Chopineau, L. et al. Phys.Rev. X 9 (2019)

[3] Porat. E. et al. Phys. Rev. Res. 4 (2022)