Plasma diagnostic tools for ECR ion sources—What can we learn from these experiments for the next generation sources

The order-of-magnitude performance leaps of ECR ion sources over the past decades result from improvements to the magnetic plasma confinement, increases in the microwave heating frequency, and techniques to stabilize the plasma at high densities. Parallel to the technical development of the ion sour...

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Bibliographic Details
Published in:Review of scientific instruments 2019-11, Vol.90 (11), p.113321-113321
Main Authors: Tarvainen, O., Kalvas, T., Koivisto, H., Kronholm, R., Marttinen, M., Sakildien, M., Toivanen, V., Izotov, I., Skalyga, V., Angot, J.
Format: Article
Language:English
Subjects:
Accelerator Physics
Confinement
Cyclotron resonance
Diagnostic software
Diagnostic systems
Electron cyclotron resonance
Electron energy distribution
Ion sources
Magnetic fields
Physics
Plasma
Plasma density
Plasma diagnostics
Plasma heating
Scaling laws
Scientific apparatus & instruments
Solenoids
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Summary:The order-of-magnitude performance leaps of ECR ion sources over the past decades result from improvements to the magnetic plasma confinement, increases in the microwave heating frequency, and techniques to stabilize the plasma at high densities. Parallel to the technical development of the ion sources themselves, significant effort has been directed into the development of their plasma diagnostic tools. We review the recent results of Electron Cyclotron Resonance Ion Source (ECRIS) plasma diagnostics highlighting a number of selected examples of plasma density, electron energy distribution, and ion confinement time measurements, obtained mostly with the second-generation sources operating at frequencies from 10 to 18 GHz. The development of minimum-B ECR ion sources based on the superposition of solenoid and sextupole fields has long relied on semiempirical scaling laws for the strength of the magnetic field with increasing plasma heating frequency. This approach is becoming increasingly difficult with the looming limits of superconducting technologies being able to satisfy the magnetic field requirements at frequencies approaching 60 GHz. Thus, we discuss alternative ECRIS concepts and proposed modifications to existing sources that are supported by the current understanding derived from the plasma diagnostics experiments.
ISSN:0034-6748
1089-7623
DOI:10.1063/1.5127050