Space-Charge Effect

TL;DR

This paper reviews the fundamental concepts of space-charge effects in high-intensity beams, discusses the Child-Langmuir law, and presents simulation methods and results including space-charge compensation in beam transport.

Contribution

It provides a comprehensive overview of space-charge phenomena, introduces a particle-in-cell simulation code with space-charge compensation, and applies it to the IFMIF injector.

Findings

Space-charge effects significantly influence beam dynamics.

The SolMaxP code effectively models space-charge compensation.

Simulation results demonstrate the impact on the IFMIF injector.

Abstract

First, this chapter introduces the expressions for the electric and magnetic space-charge internal fields and forces induced by high-intensity beams. Then, the root-mean-square equation with space charge is derived and discussed. In the third section, the one-dimensional Child-Langmuir law, which gives the maximum current density that can be extracted from an ion source, is exposed. Space-charge compensation can occur in the low-energy beam transport lines (located after the ion source). This phenomenon, which counteracts the spacecharge defocusing effect, is explained and its main parameters are presented. The fifth section presents an overview of the principal methods to perform beam dynamics numerical simulations. An example of a particles-in-cells code, SolMaxP, which takes into account space-charge compensation, is given. Finally, beam dynamics simulation results obtained with this code in the case of the IFMIF injector are presented.