Prospects of target nanostructuring for laser proton acceleration

Area of Science:

• Laser-driven particle acceleration
• Plasma physics
• Nanomaterials

Background:

• Laser-based proton acceleration aims to achieve higher proton energies.
• Nanostructured targets offer increased laser absorption, a key factor for energy boost.
• Efficient, high-repetition rate nanostructured target fabrication is crucial for applications.

Purpose of the Study:

• To investigate the impact of nanostructuring on proton acceleration.
• To evaluate nanostructured targets generated in-situ for laser-induced periodic surface structures.
• To explore the influence of nanostructuring on proton spectrum under various laser-plasma conditions.

Main Methods:

• In-situ generation of laser-induced periodic surface structures for nanostructured targets.
• Experimental investigation of proton spectra with nanostructured and plane targets.
• Theoretical simulations to analyze laser-plasma interactions and energy transfer.

Main Results:

• Nanostructuring significantly enhances laser absorption across all tested laser-plasma conditions.
• Nanostructured targets improve proton cutoff energy and conversion efficiency, especially with steep plasma gradients.
• When plasma gradients are optimized for plane targets, nanostructuring's absorption benefit does not translate to higher proton energies.

Conclusions:

• In-situ fabricated nanostructured targets are effective for laser-based proton acceleration.
• Nanostructuring overcomes limitations of plane targets in specific laser-plasma regimes.
• Energy transfer to hot electrons is identified as the limiting factor for further enhancement.