ECRIS2010 - List of Keywords (simulation)

Paper	Title	Other Keywords	Page
MOPOT004	Neutralisation of Accelerated Ions and Detection of Resulting Neutrals	ion, ion-source, ECR, acceleration	49
	T. Peleikis, L. Panitzsch, M. Stalder IEAP, Kiel, Germany
	At the University of Kiel, the Department of Experimental and Applied Physics is running an ECR ion source in order to, amongst others, calibrate space instruments designed to measure solar wind properties and suprathermal particles. The ion source is able to produce medium to highly charged ions which are then accelerated by an electrostatic field up to 400keV per charge. In order to extend the particle spectrum from ions to neutral atoms we are planning to install a device for the beam particle neutralisation. It will be used to calibrate instruments which measure neutral particles. This device will be located downstream from the sector magnet and the acceleration-stage. The sector magnet separates the ions by their m/q ratio. This way the type and the energy of the ions can be determined before the neutralisation. Neutralisation can be achieved either by passing the ions through a thin carbon foil (thickness ~88nm) or through a gastarget (thickness ~6mm, pressure ~0.1mbar) where charge-exchange occur. The remaining ions behind the neutraliser will be suppressed by an electrostatic separator. Both methods will alter the beam properties and lead to a divergence in energy and an angular spread of the beam. Simulations regarding these effects will be discussed. The overall progress on this project will be presented.
	Poster MOPOT004 [1.776 MB]

TUCOAK02	Trace Space Reconstruction From Pepperpot Data	ion, emittance, beam-transport, ECRIS	78
	H.R. Kremers, J.P.M. Beijers, S. Brandenburg, V. Mironov, J. Mulder, S. Saminathan KVI, Groningen, The Netherlands
	We use a pepperpot emittance meter to determine the full transverse trace-space distribution of low-energy ion beams. One of the problems encountered with our emittance meter is that the correlation between the measured ion images and the holes in the pepperplate is somewhat ambiguous caused by the convoluted character of the trace-space distribution. In this paper we describe a method to solve this problem and illustrate it with measurements of the 4d transverse trace-space distribution behind the analyzing magnet of a 21 keV He¹⁺ beam extracted from the KVI-AECR ion source. From these measurements together with ion-transport simulations we conclude that second-order aberrations in the analyzing magnet cause a significant increase in the effective beam emittance.
	Slides TUCOAK02 [3.474 MB]

TUCOAK03	Plasma-to-Target WARP Simulations of Uranium Beams Extracted from VENUS Compared to Emittance Measurements and Beam Images	ion, extraction, ion-source, emittance	81
	D. Winklehner, J.Y. Benitez, D. Leitner, M.M. Strohmeier, D.S. Todd LBNL, Berkeley, California, USA D.P. Grote LLNL, Livermore, California, USA
	The superconducting ECR ion source VENUS was built as injector for the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory (LBNL) and as prototype injector for the Facility for Rare Isotope Beams (FRIB) in Michigan. This work presents the latest results of an ongoing effort to simulate both, the extraction from ECR ion sources, and the Low Energy Beam Transport (LEBT). Its aim is to help understand the influence of parameters like initial ion distributions at the extraction aperture, ion temperatures and beam neutralization on the quality of the beam and to provide a design-tool for increasing the efficiency of the extraction- and transport-system. The initial conditions (i.e. spatial- and velocity-distribution of the ions prior to extraction from the ion source) are obtained semi-empirically by tracking the ions of different species from sputter marks on the biased disk on the far end of the source to the extraction region by following the magnetic field lines and scaling the Larmor radii of the ions appropriately. Extraction from the plasma and consequently the source is then simulated with the versatile WARP simulation code. The same code is also used for the actual simulation of ion transport through the beam line. Simulations of multi-species Uranium beams with different drain currents, initial ion temperatures and levels of neutralization in the beam line are compared to each other and to emittance measurements and beam profiles of VENUS beams.
	Slides TUCOAK03 [2.382 MB]

TUPOT013	Influence of Initial Plasma Density and Mean Electron Energy on the Preglow Effect	plasma, electron, ion, ECR	146
	I. Izotov, V. Sidorov, V. Skalyga, V. Zorin IAP/RAS, Nizhny Novgorod, Russia H. A. Koivisto, O.A. Tarvainen, V.A. Toivanen JYFL, Jyväskylä, Finland
	The investigation of the Preglow effect is driven with the aim of creating a short-pulsed multicharged ion source. Recent experimental investigations have revealed strong influence of seed electrons, i.e. initial plasma density, on the amplitude and duration of the Preglow peak [1]. Present work, consisting of experiments and simulations, is dedicated to further investigation of the Preglow dependence on initial plasma density and electrons energy. Experimental investigation was performed at University of Jyväskylä (JYFL) with the A-ECR type ECRIS operated with 14 GHz frequency. Helium was used for the study. An initial ionization degree of the gas was varied by changing the pulse duration and duty factor. Time-resolved ion currents of He⁺ and He²⁺ were recorded. Calculations were made by using 0-dimensional model described in references [2], [3] and based on the balance equations for the particles confined in the magnetic trap. Results of simulation are compared with experimental Preglow peaks and discussed. Good agreement between experimental data and simulation encourages us to conduct a further study, aimed at optimizing the Preglow by tuning source parameters and initial plasma conditions. [1] O. Tarvainen et al, Rev. Sci. Instrum., 81, 02A303, 2010. [2] T. Thuillier et al, Rev. Sci. Instrum., 79, 02A314, 2008. [3] I. Izotov et all. IEEE Trans. Plasma Sci. 36, 1494, 2008.
	Poster TUPOT013 [0.569 MB]

WECOAK02	Some Considerations About Frequency Tuning Effect in ECRIS Plasmas	plasma, ion, electron, resonance	165
	D. Mascali, G. Castro, L. Celona, G. Ciavola, N. Gambino, S. Gammino, R. Miracoli, L. Neri INFN/LNS, Catania, Italy F. Maimone GSI, Darmstadt, Germany
	During the last years many experiments have demonstrated that slight variations in microwave frequency used to heat and sustain the plasma of ECRIS may strongly influence their performances (frequency tuning effect) both in terms of extracted current and mean charge state. Theoretical investigations revealed that this phenomenon can be correctly explained assuming that the plasma chamber works as a resonant cavity: standing waves are excited inside of it, and their spatial structure considerably changes even with slight variations of the pumping frequency. Therefore some particular modes present a higher electric field on the resonance surface, that is the only region in which the energy transfer from waves to electrons occurs. Experimental measurements carried out on microwave discharge plasmas at high density (up to 10¹¹ cm^-3) featured that even if the absorption of electromagnetic energy at the ECR surface is evident, the stochastic nature of the wave-electron interaction allows the wave to be reflected at the extraction flange, thus forming a standing wave. The model here proposed, and based on PIC and MonteCarlo collisional simulations, puts in evidence that the frequency tuning effect in ECRIS has a global influence on plasma properties: it strongly affects both ion and electron dynamics. Electron heating, electron density distribution, ion formation and acceleration at resonance surface, beam formation are determined by the particular mode excited inside the cavity. This means that the frequency tuning will be an important tool for future ECRIS for the optimization of the beam quality (emittance, etc.).
	Slides WECOAK02 [4.765 MB]

THCOAK01	A Correction Scheme for the Hexapolar Error of an Ion Beam Extracted from an ECRIS	ion, plasma, extraction, emittance	191
	P. Spädtke, R. Lang, J. Mäder, F. Maimone, J. Roßbach, K. Tinschert GSI, Darmstadt, Germany
	The extraction of any ion beam from ECRIS is determined by the good confinement of such ion sources. It has been shown earlier, that the ions are coming from these places, where the confinement is weakest. The assumption that the low energy ions are strongly bound to the magnetic field lines require furthermore, that only these ions which start on a magnetic field line which go through the extraction aperture can be extracted. Depending on the setting of the magnetic field, these field lines may come from the loss lines at plasma chamber radius. Because the longitudinal position of these field lines depends on the azimuthal position at the extraction electrode, the ions are extracted from different magnetic flux densities. Whereas the solenoidal component is not curable, the hexapolar component can be compensated by an additional hexapole after the first beam line focusing solenoid. The hexapole has to be rotatable in azimuthal direction and moveable in longitudinal direction. For a good correction the beam needs to have such a radial phase space distribution, that the force given by this hexapole act on the aberrated beam exactly in such a way to create a linear distribution after that corrector.
	Slides THCOAK01 [1.115 MB]

THCOAK02	Kinetic Plasma Simulation of Ion Beam Extraction from an ECR Ion Source	ion, ECR, electron, ion-source	194
	S.M. Elliott, E.K. White Thin Film Consulting, Longmont, Colorado, USA J. Simkin Vector Fields Ltd., Oxford, United Kingdom
	Designing optimized ECR ion beam sources can be streamlined by the accurate simulation of beam optical properties in order to predict ion extraction behavior. The complexity of these models, however, can make PIC-based simulations time-consuming. In this paper, we first describe a simple kinetic plasma finite element simulation of extraction of a proton beam from a permanent magnet hexapole electron cyclotron resonance (ECR) ion source. Second, we analyze the influence of secondary electrons generated by ion collisions in the residual gas on the space charge of a proton beam of a dual-solenoid ECR ion source. The finite element method (FEM) offers a fast modeling environment, allowing analysis of ion beam behavior under conditions of varying current density, electrode potential, and gas pressure.
	Slides THCOAK02 [0.821 MB]

THCOAK03	Dipole Magnet Optimization for High Efficiency Low Energy Beam Transport	emittance, ECRIS, extraction, ion	197
	S. Saminathan, J.P.M. Beijers, S. Brandenburg, V. Mironov, J. Mulder KVI, Groningen, The Netherlands
	Losses in the low-energy beam transport line from KVI-AECRIS to AGOR cyclotron are estimated to be around 50%. Numerical simulations of the beam transport were performed using the tracing code LORENTZ-3D. It was found that most of the losses are due to second order optical aberrations in the 110-degree analyzing magnet. These aberrations result in an increase of the effective emittance in both horizontal and vertical directions. We will show that by suitably modifying the magnet pole surfaces the second-order aberrations can be compensated to a large extent resulting in a substantially lower effective emittance of the transported beam.
	Slides THCOAK03 [1.102 MB]

Paper

Title

Other Keywords

Page

MOPOT004

Neutralisation of Accelerated Ions and Detection of Resulting Neutrals

ion, ion-source, ECR, acceleration

49

T. Peleikis, L. Panitzsch, M. Stalder
IEAP, Kiel, Germany

At the University of Kiel, the Department of Experimental and Applied Physics is running an ECR ion source in order to, amongst others, calibrate space instruments designed to measure solar wind properties and suprathermal particles. The ion source is able to produce medium to highly charged ions which are then accelerated by an electrostatic field up to 400keV per charge. In order to extend the particle spectrum from ions to neutral atoms we are planning to install a device for the beam particle neutralisation. It will be used to calibrate instruments which measure neutral particles. This device will be located downstream from the sector magnet and the acceleration-stage. The sector magnet separates the ions by their m/q ratio. This way the type and the energy of the ions can be determined before the neutralisation. Neutralisation can be achieved either by passing the ions through a thin carbon foil (thickness ~88nm) or through a gastarget (thickness ~6mm, pressure ~0.1mbar) where charge-exchange occur. The remaining ions behind the neutraliser will be suppressed by an electrostatic separator. Both methods will alter the beam properties and lead to a divergence in energy and an angular spread of the beam. Simulations regarding these effects will be discussed. The overall progress on this project will be presented.

Poster MOPOT004 [1.776 MB]

TUCOAK02

Trace Space Reconstruction From Pepperpot Data

ion, emittance, beam-transport, ECRIS

78

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

We use a pepperpot emittance meter to determine the full transverse trace-space distribution of low-energy ion beams. One of the problems encountered with our emittance meter is that the correlation between the measured ion images and the holes in the pepperplate is somewhat ambiguous caused by the convoluted character of the trace-space distribution. In this paper we describe a method to solve this problem and illustrate it with measurements of the 4d transverse trace-space distribution behind the analyzing magnet of a 21 keV He¹⁺ beam extracted from the KVI-AECR ion source. From these measurements together with ion-transport simulations we conclude that second-order aberrations in the analyzing magnet cause a significant increase in the effective beam emittance.

Slides TUCOAK02 [3.474 MB]

TUCOAK03

Plasma-to-Target WARP Simulations of Uranium Beams Extracted from VENUS Compared to Emittance Measurements and Beam Images

ion, extraction, ion-source, emittance

81

D. Winklehner, J.Y. Benitez, D. Leitner, M.M. Strohmeier, D.S. Todd
LBNL, Berkeley, California, USA
D.P. Grote
LLNL, Livermore, California, USA

The superconducting ECR ion source VENUS was built as injector for the 88-Inch Cyclotron at Lawrence Berkeley National Laboratory (LBNL) and as prototype injector for the Facility for Rare Isotope Beams (FRIB) in Michigan. This work presents the latest results of an ongoing effort to simulate both, the extraction from ECR ion sources, and the Low Energy Beam Transport (LEBT). Its aim is to help understand the influence of parameters like initial ion distributions at the extraction aperture, ion temperatures and beam neutralization on the quality of the beam and to provide a design-tool for increasing the efficiency of the extraction- and transport-system. The initial conditions (i.e. spatial- and velocity-distribution of the ions prior to extraction from the ion source) are obtained semi-empirically by tracking the ions of different species from sputter marks on the biased disk on the far end of the source to the extraction region by following the magnetic field lines and scaling the Larmor radii of the ions appropriately. Extraction from the plasma and consequently the source is then simulated with the versatile WARP simulation code. The same code is also used for the actual simulation of ion transport through the beam line. Simulations of multi-species Uranium beams with different drain currents, initial ion temperatures and levels of neutralization in the beam line are compared to each other and to emittance measurements and beam profiles of VENUS beams.

Slides TUCOAK03 [2.382 MB]

TUPOT013

Influence of Initial Plasma Density and Mean Electron Energy on the Preglow Effect

plasma, electron, ion, ECR

146

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

The investigation of the Preglow effect is driven with the aim of creating a short-pulsed multicharged ion source. Recent experimental investigations have revealed strong influence of seed electrons, i.e. initial plasma density, on the amplitude and duration of the Preglow peak [1]. Present work, consisting of experiments and simulations, is dedicated to further investigation of the Preglow dependence on initial plasma density and electrons energy. Experimental investigation was performed at University of Jyväskylä (JYFL) with the A-ECR type ECRIS operated with 14 GHz frequency. Helium was used for the study. An initial ionization degree of the gas was varied by changing the pulse duration and duty factor. Time-resolved ion currents of He⁺ and He²⁺ were recorded. Calculations were made by using 0-dimensional model described in references [2], [3] and based on the balance equations for the particles confined in the magnetic trap. Results of simulation are compared with experimental Preglow peaks and discussed. Good agreement between experimental data and simulation encourages us to conduct a further study, aimed at optimizing the Preglow by tuning source parameters and initial plasma conditions.
[1] O. Tarvainen et al, Rev. Sci. Instrum., 81, 02A303, 2010.
[2] T. Thuillier et al, Rev. Sci. Instrum., 79, 02A314, 2008.
[3] I. Izotov et all. IEEE Trans. Plasma Sci. 36, 1494, 2008.

Poster TUPOT013 [0.569 MB]

WECOAK02

Some Considerations About Frequency Tuning Effect in ECRIS Plasmas

plasma, ion, electron, resonance

165

D. Mascali, G. Castro, L. Celona, G. Ciavola, N. Gambino, S. Gammino, R. Miracoli, L. Neri
INFN/LNS, Catania, Italy
F. Maimone
GSI, Darmstadt, Germany

During the last years many experiments have demonstrated that slight variations in microwave frequency used to heat and sustain the plasma of ECRIS may strongly influence their performances (frequency tuning effect) both in terms of extracted current and mean charge state. Theoretical investigations revealed that this phenomenon can be correctly explained assuming that the plasma chamber works as a resonant cavity: standing waves are excited inside of it, and their spatial structure considerably changes even with slight variations of the pumping frequency. Therefore some particular modes present a higher electric field on the resonance surface, that is the only region in which the energy transfer from waves to electrons occurs. Experimental measurements carried out on microwave discharge plasmas at high density (up to 10¹¹ cm^-3) featured that even if the absorption of electromagnetic energy at the ECR surface is evident, the stochastic nature of the wave-electron interaction allows the wave to be reflected at the extraction flange, thus forming a standing wave. The model here proposed, and based on PIC and MonteCarlo collisional simulations, puts in evidence that the frequency tuning effect in ECRIS has a global influence on plasma properties: it strongly affects both ion and electron dynamics. Electron heating, electron density distribution, ion formation and acceleration at resonance surface, beam formation are determined by the particular mode excited inside the cavity. This means that the frequency tuning will be an important tool for future ECRIS for the optimization of the beam quality (emittance, etc.).

Slides WECOAK02 [4.765 MB]

THCOAK01

A Correction Scheme for the Hexapolar Error of an Ion Beam Extracted from an ECRIS

ion, plasma, extraction, emittance

191

P. Spädtke, R. Lang, J. Mäder, F. Maimone, J. Roßbach, K. Tinschert
GSI, Darmstadt, Germany

The extraction of any ion beam from ECRIS is determined by the good confinement of such ion sources. It has been shown earlier, that the ions are coming from these places, where the confinement is weakest. The assumption that the low energy ions are strongly bound to the magnetic field lines require furthermore, that only these ions which start on a magnetic field line which go through the extraction aperture can be extracted. Depending on the setting of the magnetic field, these field lines may come from the loss lines at plasma chamber radius. Because the longitudinal position of these field lines depends on the azimuthal position at the extraction electrode, the ions are extracted from different magnetic flux densities. Whereas the solenoidal component is not curable, the hexapolar component can be compensated by an additional hexapole after the first beam line focusing solenoid. The hexapole has to be rotatable in azimuthal direction and moveable in longitudinal direction. For a good correction the beam needs to have such a radial phase space distribution, that the force given by this hexapole act on the aberrated beam exactly in such a way to create a linear distribution after that corrector.

Slides THCOAK01 [1.115 MB]

THCOAK02

Kinetic Plasma Simulation of Ion Beam Extraction from an ECR Ion Source

ion, ECR, electron, ion-source

194

S.M. Elliott, E.K. White
Thin Film Consulting, Longmont, Colorado, USA
J. Simkin
Vector Fields Ltd., Oxford, United Kingdom

Designing optimized ECR ion beam sources can be streamlined by the accurate simulation of beam optical properties in order to predict ion extraction behavior. The complexity of these models, however, can make PIC-based simulations time-consuming. In this paper, we first describe a simple kinetic plasma finite element simulation of extraction of a proton beam from a permanent magnet hexapole electron cyclotron resonance (ECR) ion source. Second, we analyze the influence of secondary electrons generated by ion collisions in the residual gas on the space charge of a proton beam of a dual-solenoid ECR ion source. The finite element method (FEM) offers a fast modeling environment, allowing analysis of ion beam behavior under conditions of varying current density, electrode potential, and gas pressure.

Slides THCOAK02 [0.821 MB]

THCOAK03

Dipole Magnet Optimization for High Efficiency Low Energy Beam Transport

emittance, ECRIS, extraction, ion

197

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

Losses in the low-energy beam transport line from KVI-AECRIS to AGOR cyclotron are estimated to be around 50%. Numerical simulations of the beam transport were performed using the tracing code LORENTZ-3D. It was found that most of the losses are due to second order optical aberrations in the 110-degree analyzing magnet. These aberrations result in an increase of the effective emittance in both horizontal and vertical directions. We will show that by suitably modifying the magnet pole surfaces the second-order aberrations can be compensated to a large extent resulting in a substantially lower effective emittance of the transported beam.

Slides THCOAK03 [1.102 MB]