Speaker
Description
Laser-driven ion acceleration in plasma is being explored as a source of ion beams with high peak current that can be useful in many fields of science and medicine. Recently, we introduced a new target platform using two-photon polymerization (2PP), 3D laser-printed multilayered microstructures with average densities lower than solid that are relatively insensitive to the laser prepulse. In a series of experiments at the OMEGA EP facility, we studied petawatt 1-m laser-driven ion acceleration in such 3D-printed wire microstructures [1]. Two types of microstructured targets- consisting of either a multilayered log-pile or a stochastic arrangement of one micron diameter wires are used. Although both demonstrate a higher energy and yield proton acceleration compared to thin solid-density foil targets, stochastic microstructures systematically produced higher proton energies and particle yields. The key advantage of a relatively thick 10-20 m stochastic wire structure is efficient coupling of the laser into a flux of hot electrons in the target's front and formation of an overdense, wire-related, microplasma surrounded in voids by a low-density plasma sustaining sheath field at the back on a few picoseconds time scale. This is supported by observation of additional electron heating in such a hybrid plasma resulting in generation of a stream of hot electrons in forward direction with an electron temperature, Thot up to 50MeV and with the maximum electron energy reaching 150 MeV much above the ponderomotive energy. We will discuss the results of optimization of stochastic 2PP-3D multilayer microstructures aiming to reach record proton energies in 5x1020 W/cm2 peak intensity laser-plasma interactions. This approach may become a viable alternative to nanofoils in generation of energetic ion beams that doesn’t require high-nanosecond/picosecond contrast laser pulses.
[1] S. Tochitsky et al, High-energy Ion Beams Generated with High Efficiency Using Laser-driven 3D Microstructures, Sci. Rep., (2025) 15, 37860.
| Working group | WG2 |
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