Bright gamma-rays from betatron resonance acceleration in near critical density plasma

TL;DR

This paper demonstrates that near critical density plasma enables high-brightness gamma-ray production via electron betatron resonance acceleration driven by ultra-intense lasers, with simulations and a theoretical model supporting the findings.

Contribution

It introduces a novel gamma-ray source mechanism using near critical density plasma and provides detailed simulation and analytical modeling of the process.

Findings

8.3 mJ gamma-ray emission with 1 MeV photon energy using a 7.4 J laser

Photon energy scales as $E_c \,\propto \,W_I^{1.5}$ with laser energy

Simulation results align with a new synchrotron-like radiation model.

Abstract

We show that electron betatron resonance acceleration by an ultra-intense ultra-short laser pulse in a near critical density plasma works as a high-brightness gamma-ray source. Compared with laser plasma X-ray sources in under-dense plasma, near critical density plasma provides three benefits for electron radiation: more radiation electrons, larger transverse amplitude, and higher betatron oscillation frequency. Three-dimensional particle-in-cell simulations show that, by using a 7.4J laser pulse, 8.3mJ radiation with critical photon energy 1MeV is emitted. The critical photon energy $E_c$ increases with the incident laser energy %faster than a linear relation. $W_I$ as $E_c \propto W_I^{1.5}$, and the corresponding photon number is proportional to $W_I$. A simple analytical synchrotron-like radiation model is built, which can explain the simulation results.