Influence of axial mirror ratios on the kinetic instability threshold in electron cyclotron resonance ion source plasma
Toivanen, V., Bhaskar, B. S., Koivisto, H., Maunoury, L., Tarvainen, O., & Thuillier, T. (2022). Influence of axial mirror ratios on the kinetic instability threshold in electron cyclotron resonance ion source plasma. Physics of Plasmas, 29(1), Article 013501. https://doi.org/10.1063/5.0069638
Published inPhysics of Plasmas
© 2022 the Authors
Electron Cyclotron Resonance (ECR) ion source plasmas are prone to kinetic instabilities. The onset of the instabilities manifests as emission of microwaves, bursts of electrons expelled from the plasma volume, and the collapse of the extracted highly charged ion (HCI) currents. Consequently, the instabilities limit the HCI performance of ECR ion sources by limiting the parameter space available for ion source optimization. Previous studies have shown that the transition from stable to unstable plasma regime is strongly influenced by the magnetic field structure, especially the minimum field value inside the magnetic trap (Bmin). This work focuses to study the role of the magnetic confinement on the onset of the kinetic instabilities by probing the influence of the injection and extraction mirror field variation on the instability threshold. The experiments have been performed with a room-temperature 14.5 GHz ECR ion source with an axially movable middle coil that provides flexible control over the axial field profile and especially the Bmin, which was used to quantify the variation in the instability threshold. The experimental results show that variation of the extraction field Bext, which defines the weakest magnetic mirror, correlates systematically with the variation of the instability threshold; decreasing the Bext allows higher threshold Bmin. The result demonstrates the importance of electron confinement and losses on the plasma stability. The connection between the weakest mirror field and the onset of instabilities is discussed taking into account the variation of magnetic field gradient and resonance plasma volume. ...
PublisherAmerican Institute of Physics
ISSN Search the Publication Forum1070-664X
Publication in research information system
MetadataShow full item record
Related funder(s)Academy of Finland
Funding program(s)Academy Project, AoF
Additional information about fundingThis work has been supported by the Academy of Finland Project funding (No. 315855) and University of Grenoble Alpes under the EMERGENCE program.
Showing items with similar title or keywords.
Different dynamic regimes of stimulated electron-cyclotron emission from mirror-confined non-equilibrium plasma Gospodchikov, E. D.; Shalashov, A. G.; Izotov, I. V.; Skalyga, V. A.; Tarvainen, O. (European Physical Society, 2019)
Quasi-periodical kinetic instabilities in minimum-B confined plasma Bhaskar, B. S.; Koivisto, H.; Tarvainen, O.; Thuillier, T.; Toivanen, V. (AIP Publishing, 2022)We present the results of an experimental investigation of quasi-periodical kinetic instabilities exhibited by magnetically confined electron cyclotron resonance heated plasmas. The instabilities were detected by measuring ...
The biased disc of an electron cyclotron resonance ion source as a probe of instability-induced electron and ion losses Tarvainen, O.; Kronholm, R.; Kalvas, T.; Koivisto, H.; Izotov, I.; Skalyga, V.; Toivanen, V.; Maunoury, L. (American Institute of Physics, 2019)Electron Cyclotron Resonance Ion Source (ECRIS) plasmas are prone to kinetic instabilities resulting in loss of electron and ion confinement. It is demonstrated that the biased disk of an ECRIS can be used as a probe to ...
Characteristic Kα emission of electron cyclotron resonance ion source plasmas Sakieldien, Moenir (University of Jyväskylä, 2018)This thesis presents the results of an investigation of the volumetric Kα emission rate/inner shell ionization rate from an Electron Cyclotron Resonance Ion Source (ECRIS) plasma tuned predominantly for high charge state ...
Measurements of the energy distribution of electrons lost from the minimum B-field : the effect of instabilities and two-frequency heating Izotov, I.; Tarvainen, O.; Skalyga, V.; Mansfeld, D.; Koivisto, H.; Kronholm, R.; Toivanen, V.; Mironov, V. (American Institute of Physics, 2020)Further progress in the development of electron cyclotron resonance (ECR) ion sources (ECRISs) requires deeper understanding of the underlying physics. One of the topics that remains obscure, though being crucial for the ...