ECRIS2018 - List of Authors (Tarvainen, O.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 ※ https://doi.org/10.18429/JACoW-ECRIS2018-MOA3
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MOC3	Charge Breeding Time Studies With Short Pulse Beam Injection	24
	J. Angot, M.A. Baylac, J. Jacob, T. Lamy, N. Preveraud, P. Sole, T. Thuillier LPSC, Grenoble Cedex, France O.A. Tarvainen JYFL, Jyväskylä, Finland
	Investigations on the Charge Breeding (CB) time have been done with the PHOENIX ECR Charge Breeder. The traditional measurement method consists in generating a 1+ ion beam rise front and measuring the time to reach 90% of the final steady N+ ion beam intensity. In order to study the possible self-consistent effects of the accumulation of injected ions in the plasma and to better understand the 1+N+ process, short 1+ pulses were injected and the time resolved N+ beam responses were measured. Several experimental campaigns were performed with different elements and configurations. The effect of several parameters was studied like the amplitude and the width of the pulse. The measurements were also used to estimate the 1+N+ efficiencies in the case of radioactive species. The new short pulse CB time method and the experimental results will be presented.
	Slides MOC3 [1.799 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-MOC3
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WEA1	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 WEA1 [4.895 MB]
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THA5	Gasdynamic ECR Tandem Ion Source for Negative Hydrogen Ion Production	191
	R.L. Lapin, S. Golubev, I. Izotov, S. Razin, R.A. Shaposhnikov, V. Skalyga IAP/RAS, Nizhny Novgorod, Russia O.A. Tarvainen JYFL, Jyväskylä, Finland
	Funding: The work was supported by Russian Science Foundation, Grant No. 16-12-10343. H⁻ ion sources are in great demand for beam injection into cyclotrons and storage rings utilizing charge exchange extraction or injection. The efficiency of proton beam production with the use of gasdynamic ECR ion source based on ECR discharge in a simple mirror trap has been recently demonstrated. It was then suggested to use the gasdynamic discharge as the first part of a tandem source for volumetric negative ion production. Experiments were performed with 37 GHz / up to 100 kW gyrotron power. Plasma was confined in a dual-trap magnetic system consisting of two equal simple mirror traps. The first trap was used for plasma production under the ECR condition. Dense hydrogen plasma flux from the first trap was allowed to flow into the second trap through a perforated conductive plate, which prevented propagation of the heating microwaves into the second one thus preventing plasma heating in the second chamber and allowing cold electrons to accumulate there. We present recent experimental results on this topic after optimization of the facility. We achieved a negative ion current density of 80 mA/cm² with a 1 mm plasma electrode aperture.
	Slides THA5 [1.371 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-THA5
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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 FRA1 [2.774 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-FRA1
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

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 ※ https://doi.org/10.18429/JACoW-ECRIS2018-MOA3

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOC3

Charge Breeding Time Studies With Short Pulse Beam Injection

24

J. Angot, M.A. Baylac, J. Jacob, T. Lamy, N. Preveraud, P. Sole, T. Thuillier
LPSC, Grenoble Cedex, France
O.A. Tarvainen
JYFL, Jyväskylä, Finland

Investigations on the Charge Breeding (CB) time have been done with the PHOENIX ECR Charge Breeder. The traditional measurement method consists in generating a 1+ ion beam rise front and measuring the time to reach 90% of the final steady N+ ion beam intensity. In order to study the possible self-consistent effects of the accumulation of injected ions in the plasma and to better understand the 1+N+ process, short 1+ pulses were injected and the time resolved N+ beam responses were measured. Several experimental campaigns were performed with different elements and configurations. The effect of several parameters was studied like the amplitude and the width of the pulse. The measurements were also used to estimate the 1+N+ efficiencies in the case of radioactive species. The new short pulse CB time method and the experimental results will be presented.

Slides MOC3 [1.799 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-MOC3

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEA1

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 WEA1 [4.895 MB]

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THA5

Gasdynamic ECR Tandem Ion Source for Negative Hydrogen Ion Production

191

R.L. Lapin, S. Golubev, I. Izotov, S. Razin, R.A. Shaposhnikov, V. Skalyga
IAP/RAS, Nizhny Novgorod, Russia
O.A. Tarvainen
JYFL, Jyväskylä, Finland

Funding: The work was supported by Russian Science Foundation, Grant No. 16-12-10343.
H⁻ ion sources are in great demand for beam injection into cyclotrons and storage rings utilizing charge exchange extraction or injection. The efficiency of proton beam production with the use of gasdynamic ECR ion source based on ECR discharge in a simple mirror trap has been recently demonstrated. It was then suggested to use the gasdynamic discharge as the first part of a tandem source for volumetric negative ion production. Experiments were performed with 37 GHz / up to 100 kW gyrotron power. Plasma was confined in a dual-trap magnetic system consisting of two equal simple mirror traps. The first trap was used for plasma production under the ECR condition. Dense hydrogen plasma flux from the first trap was allowed to flow into the second trap through a perforated conductive plate, which prevented propagation of the heating microwaves into the second one thus preventing plasma heating in the second chamber and allowing cold electrons to accumulate there. We present recent experimental results on this topic after optimization of the facility. We achieved a negative ion current density of 80 mA/cm² with a 1 mm plasma electrode aperture.

Slides THA5 [1.371 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-THA5

Export •

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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 FRA1 [2.774 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-ECRIS2018-FRA1

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)