A physics-based solver to improve the illumination of cylindrical targets using spherically-distributed high power laser systems

TL;DR

This paper introduces a physics-based, computationally inexpensive method for optimizing laser beam distribution on cylindrical targets, ensuring symmetric implosions in high-energy laser experiments.

Contribution

It presents a simple, differential-equation-based pointing procedure for laser beam distribution on cylindrical targets, improving symmetry in high-energy laser experiments.

Findings

Produces cylindrically symmetric implosions

Requires no complex mathematics beyond differential equations

Converges to a local optimum if it exists

Abstract

In recent years, our understanding of high energy density plasmas has played an important role in improving inertial fusion confinement and in emerging new fields of physics, such as laboratory astrophysics. Every new idea required developing innovative experimental platforms at high power laser facilities, such as OMEGA or NIF. These facilities, designed to focus all their beams onto spherical targets or hohlraum windows, are now required to shine them on more complex targets. While the pointing on planar geometries is relatively straightforward, it becomes problematic for cylindrical targets, or target with more complex geometries. This publication describes how the distribution of laser beams on a cylindrical target can be done simply by using a set of physical laws as a pointing procedure. The advantage of the method is threefold. First, it is straightforward, requiring no mathematical enterprise besides solving ordinary differential equations. Second, it will converge if a local optimum exists. Finally, it is computationally inexpensive. Experimental results show that this approach produces a geometrical beam distribution that yields cylindrically symmetric implosions.