Polychromatic drivers for inertial fusion energy

TL;DR

This paper proposes a novel polychromatic laser driver design using optical parametric amplification to enhance third-harmonic conversion efficiency and suppress laser plasma instabilities in inertial fusion energy, potentially improving fusion ignition robustness.

Contribution

It introduces a practical scheme for efficient triple-frequency conversion of broadband lasers using polychromatic drivers based on optical parametric amplification.

Findings

Over 35% energy savings from LPIs with polychromatic lasers

Large-scale simulations confirm suppression of laser plasma instabilities

Design utilizes mature optical technologies

Abstract

Although tremendous achievements have been made toward inertial confinement fusion, laser plasma instabilities (LPIs) remain to be an inevitable problem for current drive schemes. To mitigate these instabilities, significant efforts have been paid to produce high-power broadband ultraviolet lasers. However, no practical scheme has been demonstrated up to now for efficient triple-frequency conversion of broadband laser. Here we propose the design of polychromatic drivers for the generation of multicolor beams mainly based upon the optical parametric amplification, which can significantly enhance the third-harmonic conversion efficiency. Each polychromatic light has four colors of monochromatic beamlets with a full spectrum width of 3\%, and the beamlet colors of any two adjacent flanges are different. The suppression effects of such polychromatic lights have been investigated via large scale particle-in-cell simulations, which indicate that more than 35\% of the incident energy can be saved from the LPIs compared with monochromatic lasers for the direct-drive scheme, or high-density filled target for the indirect-drive scheme. The proposed polychromatic drivers are based on the matured technologies, and thus may pave the way towards realization of robust and high-efficiency fusion ignition.