A pulse length and intensity study of proton generation from microtube foil targets*

The interaction of an intense laser with a solid foil target can drive ~TV/m electric fields, accelerating ions to MeV energies. Simulations and experimental data [1,2] show that the ion energies and numbers can increase using structured targets. In this study, we experimentally observe that structured targets can dramatically enhance proton acceleration in the target normal sheath acceleration (TNSA) regime. At the Texas Petawatt Laser facility, we compared proton acceleration from a 1 µm Ag flat foil, to a fixed microtube structure 3D printed on the front side of the same foil type. A pulse length (140 – 500 fs) and intensity ( [6 – 20] ×10²⁰ W/cm²)  study found an optimum laser configuration (140 fs, 6×10²⁰ W/cm²), in which microtube targets increase the proton cutoff energy by ~2× and the energetic proton yield (>1.5 MeV) by ~3×. Experimental results are compared with 2D simulations and will be presented at the meeting.

References:

[1] L. L. Ji, et al. Scientific Reports, Scientific reports 6.1 (2016): 1-7.

[2] M. Bailly-Grandvaux, et al. Physical Review E 102.2 (2020): 021201.