# Spectral Control via Multi-Species Effects in PW-Class Laser-Ion Acceleration

## TL;DR

This paper introduces an analytical model and simulations to understand how multiple ion species influence spectral features in ultra-short, high-power laser-ion acceleration, enabling better control of ion beam properties.

## Contribution

We develop a new analytical model with inter-species interactions supported by ab initio simulations, advancing predictive control of multi-species effects in laser-ion acceleration.

## Key findings

- Multi-species effects significantly modulate ion spectra.
- The model predicts ensemble properties from spectral distributions.
- Proposed experimental setup with cryogenic hydrogen-deuterium jets.

## Abstract

Laser-ion acceleration with ultra-short pulse, PW-class lasers is dominated by non-thermal, intra-pulse plasma dynamics. The presence of multiple ion species or multiple charge states in targets leads to characteristic modulations and even mono-energetic features, depending on the choice of target material. As spectral signatures of generated ion beams are frequently used to characterize underlying acceleration mechanisms, thermal, multi-fluid descriptions require a revision for predictive capabilities and control in next-generation particle beam sources. We present an analytical model with explicit inter-species interactions, supported by extensive ab initio simulations. This enables us to derive important ensemble properties from the spectral distribution resulting from those multi-species effects for arbitrary mixtures. We further propose a potential experimental implementation with a novel cryogenic target, delivering jets with variable mixtures of hydrogen and deuterium. Free from contaminants and without strong influence of hardly controllable processes such as ionization dynamics, this would allow a systematic realization of our predictions for the multi-species effect.