ECRIS plasma spectroscopy with a high resolution spectrometer
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
Published inReview of Scientific Instruments
© 2020 Author(s)
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. I. INTR ...
PublisherAmerican Institute of Physics
Publication in research information system
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Related funder(s)Academy of Finland; European Commission
Funding program(s)Academy Project, AoF
The content of the publication reflects only the author’s view. The funder is not responsible for any use that may be made of the information it contains.
Additional information about fundingThe JYFL high resolution spectroscopy project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 654002 and the Academy of Finland under the Finnish Centre of Excellence Programme 2012–2017 (Nuclear and Accelerator Based Physics Research at JYFL, Project No. 213503) and the Academy of Finland Project funding (No. 315855).
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