CYCLOTRONS 2010 - List of Keywords (plasma)

Paper	Title	Other Keywords	Page
MOPCP016	Present Status of the RCNP Cyclotron Facility	cyclotron, ion, proton, resonance	78
	K. Hatanaka, M. Fukuda, M. Kibayashi, S. Morinobu, K. Nagayama, T. Saito, H. Tamura, T. Yorita RCNP, Osaka, Japan
	The Research Center for Nuclear Physics (RCNP) cyclotron cascade system has been operated to provide high quality beams for various experiments. In order to increase the physics research opportunities, the Azimuthally Varying Field (AVF) cyclotron facility was upgraded recently. A flat-topping system and an 18-GHz superconducting Electron Cyclotron Resonance (ECR) ion source were introduced to improve the beam's quality and intensity. A new beam line was installed to diagnose the characteristics of the beam to be injected into the ring cyclotron and to bypass the ring cyclotron and directly transport low energy beams from the AVF cyclotron to experimental halls. A separator is equipped to provide RI beams produced by fusion reactions at low energy and by projectile fragmentations at high energy. Developments have been continued to increase secondary beams as white neutrons, ultra cold neutrons, muons and unstable nucleri.

MOPCP047	Analysis of Beam Quality Optimization of Bucket Ion Source	ion, ion-source, proton, electron	147
	Y.H. Xie, C.D. Hu, C.C. Jiang, L.Z. Liang, S. Liu, Y.L. Xie ASIPP, Hefei, People's Republic of China
	Funding: The National Nature Science Foundation of China (contract number: 10875146) The bucket ion source is widely used as the high energy beam source on the high power neutral beam injector system. A hot cathode bucket ion source is studied for the diagnostic neutral beam injector. The main parameters which influence the performance of bucket ion source are arc voltage, filament voltage, gas inlet rate and extracted voltage. In the experiment, only one parameter setting is varied when other parameter settings are fixed. The characteristics of ion source are got and the parameters setting valve are as follows: four filaments current from 500 A to 550 A, arc voltage from 120 V to 200 V, and ion source pressure during discharge is from 2.0 mTorr to 4.5 mTorr, extracted voltage from 40kV to 50kV. The arc current is higher than 100 A, and extracted beam current can reaches 6 A. Based on this, the arc efficiency, beam power deposition and beam proton ratio of ion source are analyzed and optimized. The proton ratio of extracted beam increased from 28 % to 40 %. It is very useful for the experimental operation and study about the bucket ion source.

MOPCP049	Ion Source Related Research Work at JYFL	ion, ion-source, electron, resonance	150
	H. A. Koivisto, V.P. Aho, J. Ärje, T. Kalvas, J.A. Kauppinen, J.P. Kommpula, T. Ropponen, O.A. Tarvainen, V.A. Toivanen JYFL, Jyväskylä, Finland
	In this article the work of the JYFL ion source group will be presented. New bremsstrahlung measurements were carried out in order to compare the results with different electron heating models, especially defining the endpoint energy of the bremsstrahlung spectra. A project to obtain new information about the ion temperatures and their time evolution has been initiated. The study will be performed using spectroscopic techniques measuring the ion temperature through the Doppler broadening of emission lines. The objective is to reveal accurate information about the time evolution of highly charged ions in the ECRIS plasma. The work also includes frequency tuning experiments, beam quality experiments and tests with a so-called collar structure. The beneficial effect of collar was first tested and noticed with the ECR ion sources by the KVI ion source group and has been shortly confirmed at JYFL in collaboration with the KVI research group. The JYFL ion source group is also developing a low energy electron gun for the spacecraft applications. The results of the development work can possibly be applied also with the ion sources in order to increase the density of cold electrons.

MOPCP050	Studies of ECRIS Ion Beam Formation and Quality at the Department of Physics, University of Jyväskylä	ion, space-charge, ion-source, emittance	153
	V.A. Toivanen, V.P. Aho, J. Ärje, J.A. Kauppinen, H. A. Koivisto, O.A. Tarvainen JYFL, Jyväskylä, Finland L. Celona, G. Ciavola, S. Gammino, D. Mascali INFN/LNS, Catania, Italy A. Galatà INFN/LNL, Legnaro (PD), Italy T. Ropponen NSCL, East Lansing, Michigan, USA
	During the last couple of years a lot of effort has been put into studies concerning the ion beam formation and beam quality of electron cyclotron resonance ion sources (ECRISs) at the Department of Physics, University of Jyväskylä (JYFL). The effects of microwave frequency fine tuning on the performance of JYFL 14 GHz ECRIS have been studied with multiple experiments in collaboration with INFN-LNS (Instituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud). Also, a number of measurements have been carried out to study the effects of space charge compensation of ion beams on the beam quality. In order to proceed further with these studies, a modified version of the beam potential measurement device developed at LBNL (Lawrence Berkeley National Laboratory) is under development. Simulations are used to study the possibility to improve the beam quality by biasing the beginning of the beam line upstream from m/q separation. With high voltage biasing the beam energy could be increased temporarily over the limit of the injection system of the accelerator. Latest results and current status of these projects will be presented and discussed.

MOPCP053	ECR Ion Source Development at the AGOR Facility	ion, extraction, emittance, simulation	156
	V. Mironov, J.P.M. Beijers, S. Brandenburg, H.R. Kremers, J. Mulder, S. Saminathan KVI, Groningen, The Netherlands
	Funding: This work is supported by the European Union through EURONS, contract 506065 and the "Stichting voor Fundamenteel Onderzoek der Materie" (FOM). This paper reports on recent work to improve the performance of the 14 GHz KVI-AECR ion source, which is used as an injector for the AGOR cyclotron. We have installed stainless-steel screens at the injection and extraction sides and an additional collar around the extraction aperture resulting in better plasma stability and an increase of extracted ion currents. Stability and output are also improved by the use of additional RF power at 12 GHz. Source tuning is aided by continuously observing the visible light output of the plasma through the extraction aperture with a ccd camera. We now routinely extract 700 μA of O⁶⁺ and 50 μA of Pb²⁷⁺ ions. Source optimization is supported by extensive computational modeling of the ion transport in the low-energy beam line and measuring the transverse emittance of the extracted ion beam with a pepperpot emittance meter. These efforts have shown that second-order aberrations in the analyzing magnet lead to a significant increase of the effective beam emittance. Work to compensate these aberrations is underway

WEM1CIO02	28 GHz SC-ECRIS at RIBF	ion, ion-source, heavy-ion, extraction	321
	T. Nakagawa RIKEN Nishina Center, Wako, Japan
	The next generation heavy ion accelerator facility (RIBF) for production of intense RI beam requires great variety of high charged heavy ions with higher beam intensity than currently available. In the last decade, performance of the ECR ion sources has been dramatically improved with increasing the magnetic field and RF frequency to enhance the density, confinement time of plasma and electron temperature. Furthermore, the effects of the key components (magnetic field configuration, gas pressure etc) of the ion source on the ECR plasma have been revealed. Such basic studies give us how to optimize the ion source structure. Based on these studies and superconducting technology, several SC-ECRISs with higher microwave frequency (>20 GHz) were constructed. In this contribution, I present status of SC-ECRIS for RIBF, how to increase the beam intensity to meet the requirements, and the technology of the SC-ECRIS with 28GHz microwave.
	Slides WEM1CIO02 [4.179 MB]

WEM1CIO03	New Tools for the Improvement of Beam Brightness in ECR Ion Sources	electron, ion, resonance, simulation	327
	S. Gammino, L. Celona, G. Ciavola, D. Mascali INFN/LNS, Catania, Italy
	According to the model that has driven the development of ECRIS in the last years, a large variation of the pumping microwave frequency (order of GHz) along with the proportional increase of the magnetic field boosts the extracted current for each charge state because of a larger plasma density. Recent experiments have demonstrated that even slight frequency's changes (of the order of MHz) considerably influence the output current, and what's more important, even the extracted beam properties (beam shape, brightness and emittance) are affected. A number of tests have been carried out in the last few years and they will be reviewed along with the results of numerical simulations which are able to explain the observed phenomena. The frequency has been systematically changed and the beam output has been recorded either in terms of charge state distributions and beam emittance. The detected bremsstrahlung X-rays are additionally analysed: they give insights about the electron energy distribution function (EEDF). An overview about the possible future improvements of ECR ion source will be given.

WEM2CCO03	Disturbance Effects Caused by RF Power Leaking Out From Cavities in the PSI Ringcyclotron	vacuum, septum, cyclotron, proton	341
	J.M. Humbel PSI-LRF, Villigen, PSI, Switzerland H. Zhang PSI, Villigen, Switzerland
	While commissioning the PSI high intensity proton beam facility after the shutdown 2010 direct and indirect phenomena of interaction between the electrostatic septa of the injection and extraction region and the RF power, leaking out from the cavities occurred in the Ringcyclotron. As an indirect influence RF fields outside the cavities generate plasma clouds at the edge of magnet poles. Accelerated plasma ions sputtered metallic atoms form the vacuum chamber wall, which then covered the insulator surface with an electrically conductive layer. The septum therefore had to be replaced. Directly RF power, dissipated from the third harmonic cavity was redirected by a beam stopper in such a way, that a linear correlation between the RF pick up signal monitored at the extraction septum EEC and the leak current across the septum insulator could be observed. As an instant mending action the beam stopper, which is not permanently used, has been removed. The leaking out of RF power from a cavity is known to depend on vertical asymmetry. With asymmetrical settings of the hydraulic tuning system we will try to minimize this disturbing effect.
	Slides WEM2CCO03 [3.166 MB]

Paper

Title

Other Keywords

Page

MOPCP016

Present Status of the RCNP Cyclotron Facility

cyclotron, ion, proton, resonance

78

K. Hatanaka, M. Fukuda, M. Kibayashi, S. Morinobu, K. Nagayama, T. Saito, H. Tamura, T. Yorita
RCNP, Osaka, Japan

The Research Center for Nuclear Physics (RCNP) cyclotron cascade system has been operated to provide high quality beams for various experiments. In order to increase the physics research opportunities, the Azimuthally Varying Field (AVF) cyclotron facility was upgraded recently. A flat-topping system and an 18-GHz superconducting Electron Cyclotron Resonance (ECR) ion source were introduced to improve the beam's quality and intensity. A new beam line was installed to diagnose the characteristics of the beam to be injected into the ring cyclotron and to bypass the ring cyclotron and directly transport low energy beams from the AVF cyclotron to experimental halls. A separator is equipped to provide RI beams produced by fusion reactions at low energy and by projectile fragmentations at high energy. Developments have been continued to increase secondary beams as white neutrons, ultra cold neutrons, muons and unstable nucleri.

MOPCP047

Analysis of Beam Quality Optimization of Bucket Ion Source

ion, ion-source, proton, electron

147

Y.H. Xie, C.D. Hu, C.C. Jiang, L.Z. Liang, S. Liu, Y.L. Xie
ASIPP, Hefei, People's Republic of China

Funding: The National Nature Science Foundation of China (contract number: 10875146)
The bucket ion source is widely used as the high energy beam source on the high power neutral beam injector system. A hot cathode bucket ion source is studied for the diagnostic neutral beam injector. The main parameters which influence the performance of bucket ion source are arc voltage, filament voltage, gas inlet rate and extracted voltage. In the experiment, only one parameter setting is varied when other parameter settings are fixed. The characteristics of ion source are got and the parameters setting valve are as follows: four filaments current from 500 A to 550 A, arc voltage from 120 V to 200 V, and ion source pressure during discharge is from 2.0 mTorr to 4.5 mTorr, extracted voltage from 40kV to 50kV. The arc current is higher than 100 A, and extracted beam current can reaches 6 A. Based on this, the arc efficiency, beam power deposition and beam proton ratio of ion source are analyzed and optimized. The proton ratio of extracted beam increased from 28 % to 40 %. It is very useful for the experimental operation and study about the bucket ion source.

MOPCP049

Ion Source Related Research Work at JYFL

ion, ion-source, electron, resonance

150

H. A. Koivisto, V.P. Aho, J. Ärje, T. Kalvas, J.A. Kauppinen, J.P. Kommpula, T. Ropponen, O.A. Tarvainen, V.A. Toivanen
JYFL, Jyväskylä, Finland

In this article the work of the JYFL ion source group will be presented. New bremsstrahlung measurements were carried out in order to compare the results with different electron heating models, especially defining the endpoint energy of the bremsstrahlung spectra. A project to obtain new information about the ion temperatures and their time evolution has been initiated. The study will be performed using spectroscopic techniques measuring the ion temperature through the Doppler broadening of emission lines. The objective is to reveal accurate information about the time evolution of highly charged ions in the ECRIS plasma. The work also includes frequency tuning experiments, beam quality experiments and tests with a so-called collar structure. The beneficial effect of collar was first tested and noticed with the ECR ion sources by the KVI ion source group and has been shortly confirmed at JYFL in collaboration with the KVI research group. The JYFL ion source group is also developing a low energy electron gun for the spacecraft applications. The results of the development work can possibly be applied also with the ion sources in order to increase the density of cold electrons.

MOPCP050

Studies of ECRIS Ion Beam Formation and Quality at the Department of Physics, University of Jyväskylä

ion, space-charge, ion-source, emittance

153

V.A. Toivanen, V.P. Aho, J. Ärje, J.A. Kauppinen, H. A. Koivisto, O.A. Tarvainen
JYFL, Jyväskylä, Finland
L. Celona, G. Ciavola, S. Gammino, D. Mascali
INFN/LNS, Catania, Italy
A. Galatà
INFN/LNL, Legnaro (PD), Italy
T. Ropponen
NSCL, East Lansing, Michigan, USA

During the last couple of years a lot of effort has been put into studies concerning the ion beam formation and beam quality of electron cyclotron resonance ion sources (ECRISs) at the Department of Physics, University of Jyväskylä (JYFL). The effects of microwave frequency fine tuning on the performance of JYFL 14 GHz ECRIS have been studied with multiple experiments in collaboration with INFN-LNS (Instituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud). Also, a number of measurements have been carried out to study the effects of space charge compensation of ion beams on the beam quality. In order to proceed further with these studies, a modified version of the beam potential measurement device developed at LBNL (Lawrence Berkeley National Laboratory) is under development. Simulations are used to study the possibility to improve the beam quality by biasing the beginning of the beam line upstream from m/q separation. With high voltage biasing the beam energy could be increased temporarily over the limit of the injection system of the accelerator. Latest results and current status of these projects will be presented and discussed.

MOPCP053

ECR Ion Source Development at the AGOR Facility

ion, extraction, emittance, simulation

156

V. Mironov, J.P.M. Beijers, S. Brandenburg, H.R. Kremers, J. Mulder, S. Saminathan
KVI, Groningen, The Netherlands

Funding: This work is supported by the European Union through EURONS, contract 506065 and the "Stichting voor Fundamenteel Onderzoek der Materie" (FOM).
This paper reports on recent work to improve the performance of the 14 GHz KVI-AECR ion source, which is used as an injector for the AGOR cyclotron. We have installed stainless-steel screens at the injection and extraction sides and an additional collar around the extraction aperture resulting in better plasma stability and an increase of extracted ion currents. Stability and output are also improved by the use of additional RF power at 12 GHz. Source tuning is aided by continuously observing the visible light output of the plasma through the extraction aperture with a ccd camera. We now routinely extract 700 μA of O⁶⁺ and 50 μA of Pb²⁷⁺ ions. Source optimization is supported by extensive computational modeling of the ion transport in the low-energy beam line and measuring the transverse emittance of the extracted ion beam with a pepperpot emittance meter. These efforts have shown that second-order aberrations in the analyzing magnet lead to a significant increase of the effective beam emittance. Work to compensate these aberrations is underway

WEM1CIO02

28 GHz SC-ECRIS at RIBF

ion, ion-source, heavy-ion, extraction

321

T. Nakagawa
RIKEN Nishina Center, Wako, Japan

The next generation heavy ion accelerator facility (RIBF) for production of intense RI beam requires great variety of high charged heavy ions with higher beam intensity than currently available. In the last decade, performance of the ECR ion sources has been dramatically improved with increasing the magnetic field and RF frequency to enhance the density, confinement time of plasma and electron temperature. Furthermore, the effects of the key components (magnetic field configuration, gas pressure etc) of the ion source on the ECR plasma have been revealed. Such basic studies give us how to optimize the ion source structure. Based on these studies and superconducting technology, several SC-ECRISs with higher microwave frequency (>20 GHz) were constructed. In this contribution, I present status of SC-ECRIS for RIBF, how to increase the beam intensity to meet the requirements, and the technology of the SC-ECRIS with 28GHz microwave.

Slides WEM1CIO02 [4.179 MB]

WEM1CIO03

New Tools for the Improvement of Beam Brightness in ECR Ion Sources

electron, ion, resonance, simulation

327

S. Gammino, L. Celona, G. Ciavola, D. Mascali
INFN/LNS, Catania, Italy

According to the model that has driven the development of ECRIS in the last years, a large variation of the pumping microwave frequency (order of GHz) along with the proportional increase of the magnetic field boosts the extracted current for each charge state because of a larger plasma density. Recent experiments have demonstrated that even slight frequency's changes (of the order of MHz) considerably influence the output current, and what's more important, even the extracted beam properties (beam shape, brightness and emittance) are affected. A number of tests have been carried out in the last few years and they will be reviewed along with the results of numerical simulations which are able to explain the observed phenomena. The frequency has been systematically changed and the beam output has been recorded either in terms of charge state distributions and beam emittance. The detected bremsstrahlung X-rays are additionally analysed: they give insights about the electron energy distribution function (EEDF). An overview about the possible future improvements of ECR ion source will be given.

WEM2CCO03

Disturbance Effects Caused by RF Power Leaking Out From Cavities in the PSI Ringcyclotron

vacuum, septum, cyclotron, proton

341

J.M. Humbel
PSI-LRF, Villigen, PSI, Switzerland
H. Zhang
PSI, Villigen, Switzerland

While commissioning the PSI high intensity proton beam facility after the shutdown 2010 direct and indirect phenomena of interaction between the electrostatic septa of the injection and extraction region and the RF power, leaking out from the cavities occurred in the Ringcyclotron. As an indirect influence RF fields outside the cavities generate plasma clouds at the edge of magnet poles. Accelerated plasma ions sputtered metallic atoms form the vacuum chamber wall, which then covered the insulator surface with an electrically conductive layer. The septum therefore had to be replaced. Directly RF power, dissipated from the third harmonic cavity was redirected by a beam stopper in such a way, that a linear correlation between the RF pick up signal monitored at the extraction septum EEC and the leak current across the septum insulator could be observed. As an instant mending action the beam stopper, which is not permanently used, has been removed. The leaking out of RF power from a cavity is known to depend on vertical asymmetry. With asymmetrical settings of the hydraulic tuning system we will try to minimize this disturbing effect.

Slides WEM2CCO03 [3.166 MB]