A1 Journal article (refereed)
ECRIS plasma spectroscopy with a high resolution spectrometer (2020)

Kronholm, R., Kalvas, T., Koivisto, H., Kosonen, S., Marttinen, M., Neben, D., Sakildien, M., Tarvainen, O., & Toivanen, V. (2020). ECRIS plasma spectroscopy with a high resolution spectrometer. Review of Scientific Instruments, 91(1), Article 013318. https://doi.org/10.1063/1.5128854

JYU authors or editors

Publication details

All authors or editors: Kronholm, R.; Kalvas, T.; Koivisto, H.; Kosonen, S.; Marttinen, M.; Neben, D.; Sakildien, M.; Tarvainen, O.; Toivanen, V.

Journal or series: Review of Scientific Instruments

ISSN: 0034-6748

eISSN: 1089-7623

Publication year: 2020

Volume: 91

Issue number: 1

Article number: 013318

Publisher: American Institute of Physics

Publication country: United States

Publication language: English

DOI: https://doi.org/10.1063/1.5128854

Publication open access: Not open

Publication channel open access:

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/67430


Electron Cyclotron Resonance Ion Source (ECRIS) plasmas contain high-energy electrons and highly charged ions implying that only noninvasive methods such as optical emission spectroscopy are reliable in their characterization. A high-resolution spectrometer (10 pm FWHM at 632 nm) enabling the detection of weak emission lines has been developed at University of Jyväskylä, Department of Physics (JYFL) for this purpose. Diagnostics results probing the densities of ions, neutral atoms, and the temperature of the cold electron population in the JYFL 14 GHz ECRIS are described. For example, it has been observed that the cold electron temperature drops from 40 eV to 20 eV when the extraction voltage of the ion source is switched off, accompanied by two orders of magnitude decrease in Ar9+ optical emission intensity, suggesting that diagnostics results of ECRIS plasmas obtained without the extraction voltage are not depicting the plasma conditions of normal ECRIS operation. The relative changes of the plasma optical emission and the ion beam current have been measured in CW and amplitude modulation operation mode of microwave injection. It is concluded that in the CW mode, the ion currents could be limited by diffusion transport and electrostatic confinement of the ions rather than beam formation in the extraction region and subsequent transport. The high resolution of the spectrometer allows determining the ion temperature by measuring the Doppler broadening of the emission lines and subtracting the wavelength dependent instrumental broadening. The measured ion temperatures in the JYFL 14 GHz ECRIS are between 5 and 28 eV, depending on the plasma species and charge state. Gas mixing is shown to be an effective method to decrease the ion temperature of high charge state argon ions from 20 eV in pure argon discharge to 5 eV when mixed with oxygen.

Keywords: spectroscopy

Free keywords: emission spectroscopy; electron impact ionization; plasma spectroscopy; photomultipliers; doppler effect; monochromators; plasma confinement; ion sources; amplitude modulation

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Ministry reporting: Yes

Reporting Year: 2020

JUFO rating: 1

Last updated on 2021-07-07 at 21:37