Dynamic simulations of the interchange instability, ion production, and electron heating processes in an electron cyclotron resonance ion source plasma

Simulations hitherto performed with electron cyclotron resonance (ECR) ion sources (ECRIS) were mostly to predict physical quantities in their steady states. This article explores the time-dependent phenomena such as: interchange instability, ion production, and electron heating in order to simulate the time variations of hot-electron density, ion-trapping potential well, and core-electron temperature. This study has identified that the oscillations of around 1 Hz observable for these plasma parameters are a consequence of the interchange instability suffered by the hot electrons in the outer radial edge of an ECR shell. A pulsation of the ion-trapping potential well was found to take place under the unstable regime, thereby increasing the extractable ion current whenever the depth of the well is reduced due to the instability-triggered loss of electrons from the confinement. This finding may be exploited as a new method to obtain pulsed ion beams without pulsing the rf power. This article presents a form...