Author: Koivisto, H. A.
Paper Title Page
MOA3 First Ion Beams Extracted from a New JYFL 18 GHz ECRIS: HIISI 1
  • H. A. Koivisto, T. Kalvas, R.J. Kronholm, O.A. Tarvainen
    JYFL, Jyväskylä, Finland
  A new 18 GHz ECR ion source HIISI is under commissioning at the Accelerator Laboratory at the University of Jyväskylä (JYFL). The main purpose of HIISI is to produce high-energy beam cocktails, e.g. Xe44+, for radiation effects testing of electronics, and high intensity ' 5 MeV/u ion beams for international nuclear physics program with the K130 cyclotron. The initial commissioning results in 18+14 GHz operation mode using 24 segment sextupole (1.3 T) were performed in autumn 2017. In the beginning of 2018 a stronger 36 segment sextupole (1.45 T) was constructed. The first tests have been performed during the spring 2018 demonstrating improved performance of HIISI. As an example, the intensity of 0.5 mA was reached for the Ar12+ ion beam at the extraction voltage of 16 kV and total microwave power of about 2.5 kW. In this article we will present the latest development work, ion beam intensities of oxygen, argon and xenon, and future prospects of HIISI.  
DOI • reference for this paper ※  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
The Energy Distribution of Electrons Escaping Minimum-B ECR Plasma in Unstable Mode  
  • I. Izotov, D. Mansfeld, V. Skalyga
    IAP/RAS, Nizhny Novgorod, Russia
  • T. Kalvas, H. A. Koivisto, R.J. Kronholm, O.A. Tarvainen
    JYFL, Jyväskylä, Finland
  Funding: The work was supported by Russian Science Foundation, Grant No. 16-12-10343.
ECRIS plasmas are prone to kinetic instabilities associated with strong microwave emission and bursts of energetic electrons escaping the confinement*. It has been proven** that the instabilities restrict the parameter space available for the optimization of extracted beam currents of highly charged ions. Here we report the measurement of the electron energy distribution (EED) of electrons escaping axially from a minimum-B trap in unstable mode of operation where the Bmin/BECR-ratio exceeds a certain threshold value. The experimental data were recorded with 14 GHz ECRIS at the JYFL accelerator laboratory. The electrons escaping the unstable plasma through the extraction mirror of the ion source were detected with a secondary electron amplifier placed downstream from a dipole magnet serving as an electron spectrometer with 500 eV resolution. It was discovered that the EED is strongly non-Maxwellian. The comparison to EEDs acquired in stable mode, i.e. below the threshold Bmin/BECR-ratio, shows that a "hot" electron fraction with energies in the 200-300 keV range might be responsible for the development of periodic cyclotron instabilities.
* I Izotov et all, Plasma Sources Sci. Technol. 24 (2015) 045017 (9pp)
** O. Tarvainen et all, Review of Scientific Instruments 87, 02A703 (2016)
slides icon Slides WEA1 [4.895 MB]  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
FRA1 High Resolution Spectrometer Development for Use in ECR Ion Source 207
  • R.J. Kronholm, T. Kalvas, H. A. Koivisto, O.A. Tarvainen
    JYFL, Jyväskylä, Finland
  Funding: Work supported by European Union's Horizon 2020 research and innovation programme under Grant Agreement No. 654002.
A high resolution spectrometer setup have been developed for optical emission spectroscopy of ECRIS plasmas. The spectrometer has been used in multiple studies with the JYFL 14 GHz ECRIS yielding new information on the low energy electron population and ion temperatures. This is a overview of the development process and recent studies.
slides icon Slides FRA1 [2.774 MB]  
DOI • reference for this paper ※  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)