ECRIS2012 - List of Authors (Kalvas, T.)

Paper

Title

Page

An Experimental Study of ECRIS Plasma Stability and Oscillation of Beam Current

5

O.A. Tarvainen, T. Kalvas, H. A. Koivisto, J.P.O. Komppula, V. Toivanen
JYFL, Jyväskylä, Finland
C.M. Lyneis, M.M. Strohmeier
LBNL, Berkeley, California, USA

The stability of oxygen ion beams extracted from ECR ion sources has been studied with the superconducting ion source VENUS at LBNL and with the A-ECR type 14 GHz ECRIS at JYFL. Discrete Fourier transform has been used for characterizing beam current oscillations in kHz range exhibited by both ion sources. The effect of source parameters on the frequency and amplitude of the oscillations is discussed. It was found that double frequency heating affects the oscillation frequency, biased disc can be used to mitigate the amplitude of beam current fluctuations, increasing B-minimum results to pronounced instabilities and operating the ion source with significantly higher mirror ratio than suggested by ECRIS scaling laws yields the most stable ion beams. It is argued that the observed beam current fluctuations are correlated with plasma instabilities. A 'roadmap' for identifying the plasma instability mechanisms responsible for beam current fluctuations is presented.

Slides TUXO02 [2.195 MB]

TUZO03

New Extraction Design for the JYFL 14 GHz ECRIS

34

V. Toivanen, T. Kalvas, H. A. Koivisto, J.P.O. Komppula, O.A. Tarvainen
JYFL, Jyväskylä, Finland

Funding: VT acknowledges the financial support of the Ehrnrooth foundation.
A new extraction system has been designed and constructed for the JYFL 14 GHz ECRIS at the Department of Physics, University of Jyväskylä (JYFL). The goal of the new design is to improve the performance of the ion source and increase the transmission efficiency of the low energy beam transport and the accelerator. The new extraction system is designed to be able to handle higher beam currents, yield better beam quality and offer more tuning flexibility. The design was made with the aid of simulations performed with the IBSimu code. The suitability of the code for this task was verified by simulating the old extraction system and good agreement between simulations and measurements was achieved. The new extraction system has been constructed, installed and tested. The new design, simulations and the first measurement results will be presented.

Slides TUZO03 [4.470 MB]

WEXO04

Proton Beams Formation from Dense Plasma of ECR Discharge sustained by 37.5 GHz Gyrotron Radiation

85

V. Skalyga, I. Izotov, S. Razin, V. Sidorov, V. Zorin
IAP/RAS, Nizhny Novgorod, Russia
T. Kalvas, H. A. Koivisto, O.A. Tarvainen
JYFL, Jyväskylä, Finland

Funding: Work was performed in frame of realization of federal targeted program "Scientific and pedagogical labor force for an innovative Russia" for 2009-2013 yy.
Operation of modern high power accelerators often requires production of intense beams of hydrogen ions. Newer facilities aiming at outperforming the previous generation accelerators are usually designed for higher beam currents. Meeting the demand for hydrogen ion beams with higher intensity and low transverse emittance is, therefore, becoming increasingly difficult problem. Present work is devoted to experimental investigation of proton beams production from dense plasma (Ne>10¹³ cm^-3) of ECR discharge sustained by 37.5 GHz, 100 kW gyrotron radiation at SMIS 37 facility at IAP RAS. Different extraction system configurations were used. It was demonstrated that ultra bright proton beam with 4.5 mA current and 0.1 π·mm·mrad normalized emittance (brightness=45 A/(π·mm·mrad)²) can be formed with 1-hole (1 mm in diameter) extraction. For production of high current beams a 13-hole extractor was used. 200 mA and 1.1 π·mm·mrad normalized emittance proton beam was obtained. A possibility of further beam parameters enhancement by developing of extraction system and its power supply is discussed. It was shown that in generated proton beams H²⁺ component was less than 6%.

Slides WEXO04 [2.512 MB]

WEPP03

Plasma Instability in the Afterglow of ECR Discharge Sustained in a Mirror Trap

125

I. Izotov, A. Mansfeld, V. Skalyga, V. Zorin
IAP/RAS, Nizhny Novgorod, Russia
T. Grahn, T. Kalvas, H. A. Koivisto, J.P.O. Komppula, P. Peura, O.A. Tarvainen, V. Toivanen
JYFL, Jyväskylä, Finland

Funding: Work was performed in frame of realization of federal targeted program "Scientific and pedagogical labor force for an innovative Russia" for 2009-2013 yy.
A number of studies have been devoted to the investigations of plasma decay in ECR heated discharges confined in a mirror magnetic trap. The motivation of this work is to study plasma instabilities causing perturbations of ion current during the plasma decay. Present work is devoted to time-resolved diagnostics of non-linear effects observed during the afterglow plasma decay of an 14 GHz Electron Cyclotron Resonance Ion Source (ECRIS) at JYFL operated in pulsed mode. Plasma instabilities causing perturbations of extracted ion current during the decay were observed and studied. It is shown that these perturbations are associated with precipitation of high energy electrons along the magnetic field lines and strong bursts of bremsstrahlung emission. The effect of ion source settings on the onset of the observed instabilities was investigated. Based on the experimental data and estimated plasma properties it is assumed that the instabilities are of cyclotron type. The conclusion is supported by a comparison to other type of plasma devices (SMIS 37, IAP RAS) exhibiting similar characteristics but operating in a different plasma confinement regime.

FRYA03

ECRIS Related Research and Development Work at JYFL and Some Future Prospects

203

H. A. Koivisto, J.E. Ärje, T. Kalvas, J.P.O. Komppula, R.J. Kronholm, J.P. Laulainen, O.A. Tarvainen, V. Toivanen
JYFL, Jyväskylä, Finland

Since the last ECR workshop the JYFL ion source group has focused on the plasma research, work on the ion beam formation and transport and development of metal ion beams. The plasma research can be divided into plasma breakdown processes, plasma and ion beam instabilities and afterglow processes. The afterglow and instability experiments will be presented elsewhere in these proceedings [1]. In addition, studies involving in the photoelectric induced electron emission and charge exchange reactions will be briefly discussed and the experiments concerning the resonance properties of empty and plasma loaded cavity will be presented. An improvement in ion beam transport of the JYFL K130 cyclotron facility was achieved as a result of the work performed on ion beam formation. This work will be described in more detailed elsewhere in these proceedings [2]. The MIVOC method and sputtering technique were further studied in order to produce intensive titanium ion beams. As a result, an intensive {50}Ti ion beam was successfully produced with the MIVOC method and interesting behavior regarding the sputtering was noticed.
[1] V. Skalyga et al. and O. Tarvainen et al.
[2] V. Toivanen et al.

Slides FRYA03 [4.159 MB]

Paper	Title	Page
TUXO02	An Experimental Study of ECRIS Plasma Stability and Oscillation of Beam Current	5
	O.A. Tarvainen, T. Kalvas, H. A. Koivisto, J.P.O. Komppula, V. Toivanen JYFL, Jyväskylä, Finland C.M. Lyneis, M.M. Strohmeier LBNL, Berkeley, California, USA
	The stability of oxygen ion beams extracted from ECR ion sources has been studied with the superconducting ion source VENUS at LBNL and with the A-ECR type 14 GHz ECRIS at JYFL. Discrete Fourier transform has been used for characterizing beam current oscillations in kHz range exhibited by both ion sources. The effect of source parameters on the frequency and amplitude of the oscillations is discussed. It was found that double frequency heating affects the oscillation frequency, biased disc can be used to mitigate the amplitude of beam current fluctuations, increasing B-minimum results to pronounced instabilities and operating the ion source with significantly higher mirror ratio than suggested by ECRIS scaling laws yields the most stable ion beams. It is argued that the observed beam current fluctuations are correlated with plasma instabilities. A 'roadmap' for identifying the plasma instability mechanisms responsible for beam current fluctuations is presented.
	Slides TUXO02 [2.195 MB]

TUZO03	New Extraction Design for the JYFL 14 GHz ECRIS	34
	V. Toivanen, T. Kalvas, H. A. Koivisto, J.P.O. Komppula, O.A. Tarvainen JYFL, Jyväskylä, Finland
	Funding: VT acknowledges the financial support of the Ehrnrooth foundation. A new extraction system has been designed and constructed for the JYFL 14 GHz ECRIS at the Department of Physics, University of Jyväskylä (JYFL). The goal of the new design is to improve the performance of the ion source and increase the transmission efficiency of the low energy beam transport and the accelerator. The new extraction system is designed to be able to handle higher beam currents, yield better beam quality and offer more tuning flexibility. The design was made with the aid of simulations performed with the IBSimu code. The suitability of the code for this task was verified by simulating the old extraction system and good agreement between simulations and measurements was achieved. The new extraction system has been constructed, installed and tested. The new design, simulations and the first measurement results will be presented.
	Slides TUZO03 [4.470 MB]

WEXO04	Proton Beams Formation from Dense Plasma of ECR Discharge sustained by 37.5 GHz Gyrotron Radiation	85
	V. Skalyga, I. Izotov, S. Razin, V. Sidorov, V. Zorin IAP/RAS, Nizhny Novgorod, Russia T. Kalvas, H. A. Koivisto, O.A. Tarvainen JYFL, Jyväskylä, Finland
	Funding: Work was performed in frame of realization of federal targeted program "Scientific and pedagogical labor force for an innovative Russia" for 2009-2013 yy. Operation of modern high power accelerators often requires production of intense beams of hydrogen ions. Newer facilities aiming at outperforming the previous generation accelerators are usually designed for higher beam currents. Meeting the demand for hydrogen ion beams with higher intensity and low transverse emittance is, therefore, becoming increasingly difficult problem. Present work is devoted to experimental investigation of proton beams production from dense plasma (Ne>10¹³ cm^-3) of ECR discharge sustained by 37.5 GHz, 100 kW gyrotron radiation at SMIS 37 facility at IAP RAS. Different extraction system configurations were used. It was demonstrated that ultra bright proton beam with 4.5 mA current and 0.1 π·mm·mrad normalized emittance (brightness=45 A/(π·mm·mrad)²) can be formed with 1-hole (1 mm in diameter) extraction. For production of high current beams a 13-hole extractor was used. 200 mA and 1.1 π·mm·mrad normalized emittance proton beam was obtained. A possibility of further beam parameters enhancement by developing of extraction system and its power supply is discussed. It was shown that in generated proton beams H²⁺ component was less than 6%.
	Slides WEXO04 [2.512 MB]

WEPP03	Plasma Instability in the Afterglow of ECR Discharge Sustained in a Mirror Trap	125
	I. Izotov, A. Mansfeld, V. Skalyga, V. Zorin IAP/RAS, Nizhny Novgorod, Russia T. Grahn, T. Kalvas, H. A. Koivisto, J.P.O. Komppula, P. Peura, O.A. Tarvainen, V. Toivanen JYFL, Jyväskylä, Finland
	Funding: Work was performed in frame of realization of federal targeted program "Scientific and pedagogical labor force for an innovative Russia" for 2009-2013 yy. A number of studies have been devoted to the investigations of plasma decay in ECR heated discharges confined in a mirror magnetic trap. The motivation of this work is to study plasma instabilities causing perturbations of ion current during the plasma decay. Present work is devoted to time-resolved diagnostics of non-linear effects observed during the afterglow plasma decay of an 14 GHz Electron Cyclotron Resonance Ion Source (ECRIS) at JYFL operated in pulsed mode. Plasma instabilities causing perturbations of extracted ion current during the decay were observed and studied. It is shown that these perturbations are associated with precipitation of high energy electrons along the magnetic field lines and strong bursts of bremsstrahlung emission. The effect of ion source settings on the onset of the observed instabilities was investigated. Based on the experimental data and estimated plasma properties it is assumed that the instabilities are of cyclotron type. The conclusion is supported by a comparison to other type of plasma devices (SMIS 37, IAP RAS) exhibiting similar characteristics but operating in a different plasma confinement regime.

FRYA03	ECRIS Related Research and Development Work at JYFL and Some Future Prospects	203
	H. A. Koivisto, J.E. Ärje, T. Kalvas, J.P.O. Komppula, R.J. Kronholm, J.P. Laulainen, O.A. Tarvainen, V. Toivanen JYFL, Jyväskylä, Finland
	Since the last ECR workshop the JYFL ion source group has focused on the plasma research, work on the ion beam formation and transport and development of metal ion beams. The plasma research can be divided into plasma breakdown processes, plasma and ion beam instabilities and afterglow processes. The afterglow and instability experiments will be presented elsewhere in these proceedings [1]. In addition, studies involving in the photoelectric induced electron emission and charge exchange reactions will be briefly discussed and the experiments concerning the resonance properties of empty and plasma loaded cavity will be presented. An improvement in ion beam transport of the JYFL K130 cyclotron facility was achieved as a result of the work performed on ion beam formation. This work will be described in more detailed elsewhere in these proceedings [2]. The MIVOC method and sputtering technique were further studied in order to produce intensive titanium ion beams. As a result, an intensive {50}Ti ion beam was successfully produced with the MIVOC method and interesting behavior regarding the sputtering was noticed. [1] V. Skalyga et al. and O. Tarvainen et al. [2] V. Toivanen et al.
	Slides FRYA03 [4.159 MB]