Undepleted direct laser acceleration

Abstract

Intense lasers enable generating high-energy particle beams in university-scale laboratories. With the direct laser acceleration (DLA) method, the leading part of the laser pulse ionizes the target material and forms a positively charged ion plasma channel into which electrons are injected and accelerated. The high energy conversion efficiency of DLA makes it ideal for generating large numbers of photonuclear reactions. In this work, we reveal that, for efficient DLA to prevail, a target material of sufficiently high atomic number is required to maintain the injection of ionization electrons at the peak intensity of the pulse when the DLA channel is already formed. We demonstrate experimentally and numerically that, when the atomic number is too low, the target is depleted of its ionization electrons prematurely. Applying this understanding to multi-petawatt laser experiments is expected to result in increased neutron yields, a perquisite for a wide range of research and applications.

Comparative Study of Plasma-Enhanced-Atomic-Layer-Deposited Al2O3/HfO2/SiO2 and HfO2/Al2O3/SiO2 Trilayers for Ultraviolet Laser Applications

“…With the rapid development of laser technology over the past few decades, the need for low-defect and high-bandgap dielectrics with high laser damage resistance has become critical to the future of thin film optics to sustain the increasing power of laser facilities such as inertial confinement fusion, extreme light infrastructure, and laser-driven particle acceleration. , Under laser irradiation with pulse widths in the nanosecond (ns) range, damage to dielectrics in the ultraviolet (UV) to near-infrared (NIR) wavelength range is mainly attributed to the photothermal effect. Defects in the dielectric absorb laser energy, causing localized heat accumulation and thermal expansion, leading to melting or mechanical stripping of the thin film .…”