Radiation safety challenges in plasma accelerators

TL;DR

This paper examines radiation safety challenges in plasma accelerators, emphasizing the need for tailored shielding and safety protocols due to unique beam loss patterns and radiation fields.

Contribution

It provides a detailed analysis of radiation safety issues in plasma accelerators using simulations and experimental data, highlighting the importance of dedicated safety measures.

Findings

Significant dose rates occur at electron energies of several MeV.

Radiation fields are prominent near the plasma source.

Dedicated shielding is necessary for future plasma accelerator facilities.

Abstract

Plasma accelerators are rapidly evolving toward user-relevant machines with increasing repetition rates, particle energies and average beam powers. Despite their compact size, the operational characteristics of plasma accelerators are comparable to those of radio-frequency linacs, involving the continuous generation and dumping of electron bunches. However, beam properties and loss patterns can differ substantially from those of conventional accelerators, leading to radiation safety considerations dominated by high peak charges and distributed beam losses relevant for both personnel protection and machine integrity. Using established scaling laws, we show that significant dose rates already occur at electron energies of several MeV, underscoring the relevance of radiation protection even for comparatively low-energy plasma accelerators. Based on a combination of Monte Carlo and particle-in-cell simulations, supported by radiation measurements from plasma accelerator experiments at DESY, we analyze typical radiation fields with a particular focus on radiation generated close to the plasma source. These findings highlight the need for dedicated shielding and beam-dump concepts tailored to plasma accelerators, especially in view of increasing average beam powers and future application-oriented operation.