Charged Particle Stopping Power Effects on Ignition: Some Results from an Exact Calculation

TL;DR

This paper presents an exact first-principles calculation of charged particle stopping power relevant to inertial confinement fusion, revealing longer alpha particle ranges and reduced ion energy deposition compared to previous models, which impacts ignition conditions.

Contribution

It provides a rigorous, quantum-mechanically accurate calculation of stopping power that improves upon previous models for fusion plasma conditions.

Findings

Alpha particle range is 20-30% longer than previous predictions.

Energy deposition into ions is smaller than in earlier models.

Increased rho-R requirement for ignition based on simulations.

Abstract

A completely rigorous first-principles calculation of the charged particle stopping power has recently been performed by Brown, Preston, and Singleton (BPS). This calculation is exact to leading and next-to-leading order in the plasma number density, including an exact treatment of two-body quantum scattering. The BPS calculation is therefore extremely accurate in the plasma regime realized during the ignition and burn of an inertial confinement fusion capsule. For deuterium-tritium fusion, the 3.5 MeV alpha particle range tends to be 20-30% longer than most models in the literature have predicted, and the energy deposition into the ions tends to be smaller. Preliminary numerical simulations indicate that this increases the rho-R required to achieve ignition.