A Renewable Double Plasma Mirror For Petawatt-class Lasers

TL;DR

This paper introduces a novel renewable double plasma mirror system using ultrathin liquid crystal films, significantly improving pulse contrast and throughput for petawatt-class lasers, enabling high repetition rate operation.

Contribution

It presents the first scalable, renewable plasma mirror design with a predictive model for peak reflectivity, advancing high-power laser contrast enhancement technology.

Findings

Achieved 80% total throughput in the system

Demonstrated 2-3 orders of magnitude improvement in contrast

Validated a new model predicting plasma mirror reflectivity

Abstract

Exceptional pulse contrast can be critical for ultraintense laser experiments, particularly when using solid density targets, and their use is becoming widespread. However, current plasma mirror technology is becoming inadequate for the new generation of high repetition rate, high power lasers now available. We describe a novel double plasma mirror configuration based on renewable, free standing, ultrathin liquid crystal films tested at the BELLA Petawatt Laser Center. Although operating at a repetition rate of several shots per minute, this system can be scaled to a high repetition rate exceeding 1 Hz and represents an important step towards enabling sustained, continuous operation of plasma mirrors. We demonstrate an improvement of two to three orders of magnitude in contrast and a total throughput of 80%. We present the first measurements of a beam reflected from a single or double plasma mirror system using a wavefront sensor, showing a well preserved wavefront and spatial mode. Finally, we introduce a model that predicts the total throughput through this double plasma mirror. This is the first model that accurately predicts the peak reflectivity of a plasma mirror when given the laser temporal profile.