Parametric study of voltage in plasma-discharge capillary systems: a benchmarking of experimental and simulation data

Abstract We explore the use of gas-filled plasma-discharge capillaries for laser wakefield acceleration (LWFA) by employing a hybrid system that integrates an external high-voltage source to driven an electrical discharge, generate plasma within the capillary channel before to the main laser pulse. The process enhances plasma formation, boosts operational efficiency, and maintains laser intensity over multiple Rayleigh lengths, enabling high-energy electron acceleration. The electrical discharge creates a stable, uniform plasma environment, improving beam charge, energy stability, and reducing energy spread. This uniform plasma ensures better laser coupling and mitigates instabilities, leading to improved beam quality. This method supports efficient acceleration and the production of very-high-energy electron (VHEE) pencil beams (250 MeV) in a compact, cost-effective system designed for radiobiological studies at the future I-LUCE ( I NFN- L aser ind UCE d Radiation Production) facility at the Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali del Sud (INFN-LNS) in Catania, Italy. The system aims to generate high-energy electron beams tailored for VHEE and FLASH radiotherapy (FLASH-RT) applications. In this paper, we present simulations of capillaries performed using COMSOL Multiphysics software, where plasma density is obtained as a function of the applied voltage. We analyze plasma behavior under varying voltage and compare the results with experimental data, demonstrating the model's accuracy in predicting plasma characteristics and its potential to optimize discharge conditions.