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. (2020). Measurements of the energy distribution of electrons lost from the minimum B-field : the effect of instabilities and two-frequency heating. Review of Scientific Instruments, 91(1), Article 013502. https://doi.org/10.1063/1.5128322
Julkaistu sarjassaReview of Scientific Instruments
© 2020 the Author(s)
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 performance of the ECRIS, is the electron energy distribution (EED). A well-developed technique of measuring the EED of electrons escaping axially from the magnetically confined plasma of an ECRIS was used for the study of the EED in an unstable mode of plasma confinement, i.e., in the presence of kinetic instabilities. The experimental data were recorded for pulsed and CW discharges with a room-temperature 14 GHz ECRIS at the JYFL accelerator laboratory. The measurements were focused on observing differences between the EED escaping from stable and unstable plasmas. It was found that nonlinear phenomena alter the EED noticeably. The electron losses are enhanced in both unstable regimes, with two-frequency heating suppressing the instabilities. It has been shown earlier that two-frequency heating boosts the ECRIS performance presumably owing to the suppression of instabilities. We report the observed changes in EED introduced by the secondary frequency in different regimes, including an off-resonance condition, where the secondary frequency is lower than the minimum frequency satisfying the resonance condition for cold electrons at the magnetic field minimum. Finally, we suggest an experimental method of qualitative evaluation of the energy distribution of electrons confined in the magnetic trap using a method of measuring energy distribution of lost electrons during the plasma decay in pulsed operation of the ion source. ...
JulkaisijaAmerican Institute of Physics
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Lisätietoja rahoituksestaThe experiment was supported by the Academy of Finland Project No. 315855. The data processing and analysis was supported by the Russian Science Foundation, Project No. 19-12-00377.
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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. (American Institute of Physics, 2022)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 ...
Li, Jibo; Li, lixuan; Bhaskar, Bichu; Toivanen, Ville; Tarvainen, Olli; Hitz, Denis; Li, Libin; Lu, Wang; Koivisto, Hannu; Thuillier, Thomas; Guo, Junwei; Zhang, Xuezhen; Zhao, Huanyu; Sun, Lingting; Zhao, Hongwei (IOP Publishing, 2020)To investigate the hot electron population and the appearance of kinetic instabilities in highly charged electron cyclotron resonance ion source (ECRIS), the axially emitted bremsstrahlung spectra and microwave bursts ...
Izotov, Ivan; Tarvainen, Olli; Skalyga, Vadim; Mansfeld, Dmitry; Kalvas, Taneli; Koivisto, Hannu; Kronholm, Risto (IOP Publishing, 2018)The measurement of the electron energy distribution (EED) of electrons escaping axially from a minimum-B electron cyclotron resonance ion source (ECRIS) is reported. The experimental data were recorded with a room-temperature ...
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 ...
Toivanen, V.; Bhaskar, B. S.; Izotov, I. V.; Koivisto, H.; Tarvainen, O. (American Institute of Physics, 2022)The performance of a minimum-B Electron Cyclotron Resonance Ion Source (ECRIS) is traditionally quantified by measuring the beam current and quality of the extracted ion beams of different charge state ions. The stability ...