Laser-driven Ion and Neutron Sources from Medium Repetition Ultrashort PW Laser

TL;DR

This study demonstrates laser-driven ion acceleration and neutron generation using medium-repetition ultrashort PW laser pulses on thin plastic targets, revealing linear energy scaling with laser intensity and effective neutron production.

Contribution

First experimental investigation of ion acceleration and neutron generation with 4PW laser on plastic targets, highlighting new scaling laws and neutron yields.

Findings

Ion energies increase linearly with laser intensity.

Ion energy scales as q^2/mass, similar to ponderomotive acceleration.

Neutron spectrum extends up to 15MeV with yields comparable to existing sources.

Abstract

We report the first experiment investigating ion acceleration and neutron generation irradiating thin plastic targets (CH2) and deuterated plastic targets (CD2) of thickness ranging from 30nm to 160nm using the 4PW (0.1 Hz) laser at CoReLS in South Korea. Thin wedge-shaped filters exploiting differing stopping ranges were designed to distinguish carbon 6+ ions from deuterons in shots with CD2 targets. The maximum energies of all ion species from both CH2 and CD2 targets were found to increase linearly with the laser intensity. The highest observed energy of each ion species scales as q (charge)^2/mass, which is more similar to the scaling expected for ponderomotive acceleration than to the scaling expected for TNSA. The maximum ion energies were also found to increase with target thickness. Utilizing the secondary interactions of the deuteron beam, we created a fast neutron source via deuteron breakup reactions on a copper converter. The neutron spectrum follows an exponential distribution with energy up to 15MeV. A neutron yield of 2x10^7n/J was observed from thicker targets, comparable to TNSA-regime laser-driven neutron sources and within one order of magnitude of the highest yields reported using Break-out-afterburner (BOA) acceleration with beryllium converters.