Transport of intense ion beams in plasmas: collimation and energy-loss reduction

TL;DR

This paper investigates how intense proton beams interact with plasmas, revealing that resistive magnetic fields can both collimate the beam and reduce energy-loss, supported by experimental data and advanced simulations.

Contribution

The study introduces a new particle-in-cell simulation that captures electromagnetic and collisional effects, explaining energy-loss reduction and collimation in high-current proton beam transport.

Findings

Resistive magnetic fields collimated the proton beam.

Energy-loss was significantly reduced in high-current beams.

Simulations matched experimental observations.

Abstract

We compare the transport properties of a well-characterized hydrogen plasma for low and high current ion beams. The energy-loss of low current beams can be well understood, within the framework of current stopping power models. However, for high current proton beams, significant energy-loss reduction and collimation is observed in the experiment. We have developed a new particle-in-cell code, which includes both collective electromagnetic effects and collisional interactions. Our simulations indicate that resistive magnetic fields, induced by the transport of an intense proton beam, act to collimate the proton beam and simultaneously deplete the local plasma density along the beam path. This in turn causes the energy-loss reduction detected in the experiment.