Influence of Wall-Current-Compensation and Secondary-Electron-Emission on the Plasma Parameters and on the Performance of Electron Cyclotron Resonance Ion Sources

Journal Article · Tue Mar 15 00:00:00 EST 2005 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.1893403· OSTI ID:20630673

Schachter, L; Dobrescu, S ^[1]; Stiebing, K E ^[2]

---

1. National Institute for Physics and Nuclear Engineering, Bucharest (Romania)
2. Institut fuer Kernphysik der Johann Wolfgang Goethe-Universitaet, Frankfurt (Germany)

Axial and radial diffusion processes determine the confinement time in an ECRIS. It has been demonstrated that a biased disk redirects the ion- and electron currents in the source in such a way that the source performance is improved. This effect is due to a partial cancellation of the compensating currents in the conductive walls of the plasma chamber.In this contribution we present an experiment, where these currents were effectively suppressed by using a metal-dielectric (MD) disk instead of the standard metallic disk in the Frankfurt 14-GHz-ECRIS. Lower values of the plasma potential and higher average charge states in the presence of the MD disk as compared to the case of the standard disk indicate that, due to the insulating properties of its dielectric layer the MD disk obviously blocks compensating wall currents better than applying bias to the metallic standard disk.A comparison with results from experiments with a MD liner in the source, covering essentially the complete radial walls of the plasma chamber, clearly demonstrates that the beneficial effect of the liner on the performance of the ECRIS is much stronger than that observed with the MD-disk. In accord with our earlier interpretation, it has to be concluded that the 'liner-effect' is not just the effect of blocking the compensating wall currents but rather has to be ascribed to the unique property of the thin MD liner as a strong secondary electron emitter under bombardment by charged particles.

• OSTI ID: 20630673
• Journal Information: AIP Conference Proceedings, Vol. 749, Issue 1; Conference: ECRIS'04: 16. international workshop on ECR ion sources, Berkeley, CA (United States), 26-30 Sep 2004; Other Information: DOI: 10.1063/1.1893403; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

73 NUCLEAR PHYSICS AND RADIATION PHYSICS
43 PARTICLE ACCELERATORS
CHARGE STATES
COMPARATIVE EVALUATIONS
CONFINEMENT TIME
CYCLOTRON RESONANCE
DIELECTRIC MATERIALS
DIFFUSION
ECR ION SOURCES
ELECTRIC CURRENTS
ELECTRON EMISSION
ELECTRONS
GHZ RANGE
LINERS
PERFORMANCE
PLASMA
PLASMA CONFINEMENT
PLASMA POTENTIAL