Cyclotrons2013 - List of Keywords (electron)

Paper	Title	Other Keywords	Page
TU2PB01	A Study of Multipacting Effects in Large Cyclotron Cavities by Means of Fully 3-Dimensional Simulations	simulation, cavity, cyclotron, RF-structure	142
	C. Wang, B. Ji, Y. Lei, P.Z. Li, J.S. Xing, Z.G. Yin, T.J. Zhang CIAE, Beijing, People's Republic of China A. Adelmann, A. Gsell, M. Seidel PSI, Villigen PSI, Switzerland
	The field emission model and the secondary emission model, as well as 3D boundary geometry handling capabilities, are needed to efficiently and precisely simulate multipacting phenomena. These models have been implemented in OPAL, a parallel framework for charged particle optics in accelerator structures and beam lines. The models and their implementation are carefully benchmarked against a non-stationary multipacting theory. A dedicated multipacting experiment with nanosecond time resolution for the classic parallel plate geometry has also successfully shown the validity of OPAL model. Multipacting phenomena, in the CYCIAE-100 cyclotron, under construction at China Institute of Atomic Energy, are expected to be more severe during the RF conditioning process than in separate-sector cyclotrons. This is because the magnetic fields in the valley are stronger, which may make the impact electrons easier to reach energies that lead to larger multipacting probabilities. We report on simulation results for CYCIAE-100, which gives us an insight view of the multipacting process and help to develop cures to suppress these phenomena.
	Slides TU2PB01 [7.012 MB]

TUPPT013	Simulation of Sufficient Spindle Cusp Magnetic Field for 28 GHz ECRIS	plasma, ECRIS, ion, ECR	180
	M.H. Rashid, A. Chakrabarti VECC, Kolkata, India
	A cusp magnetic field (CMF) configuration is proposed for achieving more plasma confinement. It is an improved version of CMF compared to the classical one used earlier to design arbitrarily ECR ion source (ECRIS) of low frequency. The CMF has been reconfigured here adopting a simple, novel and cost-effective technique to shrink the loss area and to achieve denser plasma than in traditional ECRIS. The strength of the electron (plasma) confinement is demonstrated through electron simulations. It consists of a mid-iron disk, two end-plugs and a pair of superconducting magnet coils cooled by cryo-coolers. It is designed for high-B mode operation of the cusp ECRIS of as high as 28 GHz RF frequency for producing an intense beam of highly charged heavy ions. The electric current in the coil at the extraction end can be manipulated to optimize the operation to achieve high extracted beam current of highly charged ions.

TUPPT014	Characterization of the Versatile Ion Source (VIS) for the Production of Monocharged Light Ion Beams	plasma, ion, proton, ion-source	183
	L. Celona, L. Calabretta, G. Castro, G. Ciavola, S. Gammino, D. Mascali, L. Neri, G. Torrisi INFN/LNS, Catania, Italy G. Castro Universita Degli Studi Di Catania, Catania, Italy F. Di Bartolo INFN & Messina University, S. Agata, Messina, Italy
	Funding: The support of the 5th National Committee of INFN is gratefully acknowledged. The Versatile Ion Source (VIS) is an off-resonance Microwave Discharge Ion Source which produces a slightly overdense plasma at 2.45 GHz of pumping frequency. In the measurements carried out at INFN-LNS in the last two years, VIS was able to produce more than 50 mA of proton beams and He⁺ beams at 65 kV, while for H²⁺ a current of 15 mA was obtained. The know-how obtained with the VIS source has been useful for the design of the proton source of the European Spallation Source, to be built in Lund, Sweden, and it will be used also for other facilities. In particular, the design modifications of the VIS source under study at INFN-LNS, in order to use the new source as the injector of H²⁺ at the ISODAR facility, will be also presented.

TUPPT018	Critical Analysis of Negative Hydrogen Ion Sources for Cyclotrons	ion, ion-source, plasma, cyclotron	192
	S. Korenev Siemens Medical Solutions Molecular Imaging, Knoxville, TN, USA
	The ion sources for cyclotrons based on negative hydrogen ions found applications as basic injectors for cyclotrons. The main important questions of negative hydrogen ion sources are following: i) method of production for negative hydrogen ions, ii) the extraction of ions and iii) separation of negative ions from electrons. Among of ion internal and external ion sources the common question is efficiency for production of negative hydrogen ions and increasing of kinetic energy of these ions. The critical analysis of different ions sources (PIG, Multicusps, etc.) is given. The comparison of these ion sources regarding applications for industrial cyclotrons for production of medical isotopes is presented in the paper.
	Poster TUPPT018 [0.231 MB]

TUPPT019	Development Study of Penning Ion Source for Compact 9 MeV Cyclotron	ion, cathode, ion-source, plasma	195
	Y.H. Yeon, J.-S. Chai, T.V. Cong, Kh.M. Gad, M. Ghergherehchi, S.Y. Jung, H.S. Kim, H.W. Kim, S.H. Kim, S.H. Lee, Y.S. Lee, X.J. Mu, S.Y. Oh, S. Shin SKKU, Suwon, Republic of Korea
	Funding: This research was supported by WCU (World Class University) program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology (R31-2008-10029). Penning Ion Gauge(PIG) have been used in internal source for cyclotron. PIG source for internal source of 9 MeV cyclotron produces H⁻ ion. This source consists of cold cathode which discharges electrons for producing H⁻ ion and anode for making plasma wall. Cold cathode material tantalum was used for emitting electrons and tungsten copper alloy was used for anode. The size of PIG source is related to size of cyclotron magnet. Optimization of cathode and anode location and sizing were needed for simplifying this source for reducing the size of compact cyclotron. Transportation of electrons and number of secondary electrons has been calculated by CST particle studio. Motion of H2 gas has been calculated by ANSYS. Calculation of PIG source in 9 MeV cyclotron has been performed by using various chimneys with different size of expansion gap between the plasma boundary and the chimney wall. In this paper design process and experiment result is reported.

TUPSH005	Investigation of Cyclotron Carbon Foil Lifetime in Relation to its Thickness	proton, ion, cyclotron, radiation	227
	J.-W. Kim, S. Hong, J.H. Kim IBS, Daejeon, Republic of Korea Y. Choi Dongguk University, Gyeongju, Republic of Korea Y.-S. Kim Energy & Environmental System, Gyeongju, Republic of Korea
	For extracting positive hydrogen atoms from accelerated negative ones, a thin carbon foil is usually used to stripe two electrons from negative atoms, which consists of one proton and two electrons traveling together up to 70MeV proton. The kinetic energy of electron is 38.13keV at the moment of stripping. The energy loss of protons and electrons in carbon foil could be estimated by the multiplication of stopping power (dE/dz) and the foil thickness where passing through. The stopping powers were estimated with 8.5 and 7.25 MeV/(g/cm²) for the proton and electron, respectively. In cyclotron the stripper is located in a strong magnetic field of ~Tesla, which makes electrons circular motion around the foil depositing all their kinetic energies into it. In this study, three different carbon foil thicknesses (200, 400, and 800 ug/cm²) were employed to investigate the correlation of foil temperature and their lifetime for the case of 1mA proton extraction. We are aiming the lifetime of a stripper foil to be as long as 2 weeks for irradiating protons onto an ISOL target. An effective lifetime of foils will be discussed as a function of a foil peak temperature.

TU3PB01	Bunch-Shape Measurements at PSI’s High-power Cyclotrons and Proton Beam Lines	proton, cyclotron, cathode, simulation	257
	R. Dölling PSI, Villigen PSI, Switzerland
	Longitudinal-transversal 2D-density distributions of the bunched 2.2 mA CW proton beam can now be measured at the 13 last turns of the Injector 2 cyclotron, at several locations in the connecting beam line to the Ring cyclotron, at the first two turns of the Ring cyclotron (all at energies around 72 MeV), as well as behind the Ring cyclotron (at 590 MeV). In the large part, distributions can be taken from several angles of view, separated each by 45°. The measurement systems at our facility have evolved with time; this paper gives the present status, performance, limits and typical results. Due to the limited space, we refer in the large part to our previous publications [1, 2, 3] and concentrate on recent findings and measurements and ideas for next steps.
	Slides TU3PB01 [9.393 MB]

TU3PB03	R&D of Helium Gas Stripper for Intense Uranium Beams	ion, target, acceleration, cyclotron	265
	H. Imao, T. Dantsuka, M. Fujimaki, N. Fukunishi, H. Hasebe, O. Kamigaito, M. Kase, H. Kuboki, K. Kumagai, T. Maie, H. Okuno, T. Watanabe, Y. Watanabe, K. Yamada, Y. Yano RIKEN Nishina Center, Wako, Japan
	Intensity upgrade of uranium beams is one of the main concerns at the RIKEN Radioactive Isotope Beam Factory (RIBF). The lifetime problem of carbon-foil strippers due to the high energy loss of uranium beams around 10~MeV/u was a principal bottleneck for the intensity upgrade in the acceleration scheme at the RIBF. We have developed a re-circulating He-gas stripper as an alternative to carbon foils for the acceleration of high-power uranium beams. The new stripping system was actually operated in user runs with U³⁵⁺ beams of more than 1 puA. Electron-stripped U⁶⁴⁺ beams were stably delivered to subsequent accelerators without serious deterioration of the system for six weeks. The new He-gas stripper, which removed the primary bottleneck in the high-intensity uranium acceleration, greatly contributed the tenfold increase of the average output intensity of the uranium beams from the previous year.
	Slides TU3PB03 [11.983 MB]

TU3PB04	TRIUMF Extraction Foil Developments and Contamination Reduction	extraction, scattering, simulation, TRIUMF	269
	Y.-N. Rao, R.A. Baartman, I.V. Bylinskii, V.A. Verzilov TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada J.M. Schippers PSI, Villigen PSI, Switzerland
	Funding: TRIUMF receives funding via a contribution agreement through the National Research Council of Canada. We made important developments on the extraction probes and stripping foils at TRIUMF. One of the issues we had was the ⁷Be contamination being observed near the 1A stripper, and relatedly, stripping foils warped or even broke during use. This was deemed due to over-heating in the foil and the frame. Another issue was related to the beam spills. Beam spills are primarily caused by the large angle scattering from the stripping foil. It was thus suggested that thinner foils be used to minimize the scattering. In view of these 2 issues, improvements were made such that (1) highly-orientated pyrolytic graphite foils, of thickness around 2 mg/cm², are now used; (2) Tantalum frame is now used in place of the previous stainless steel. These changes, plus additional heat relief features introduced, have resulted in 4 times longer lifetime with the foil, and 5 to 10 times reduction to the tank contamination level around the extraction probe. Also, these improvements have led to significantly reduced amount of beam spill monitor trips. This paper presents these developments and outcomes, including the simulations and calculations performed.
	Slides TU3PB04 [4.798 MB]

TU4PB02	Structural and Magnetic Properties of Cast Iron for Cyclotrons	cyclotron, controls, induction, polarization	275
	E. Forton, S. Zaremba IBA, Louvain-la-Neuve, Belgium E. Ferrara, F. Fiorillo, L. Martino, E. Olivetti, L. Rocchino INRIM, Turin, Italy
	At IBA, the steels used to build the magnets of the Cyclone 230 are cast on demand, using very strict criteria, casting procedure, requirements and quality control. Among the various steps performed at the foundry, a thermal annealing is made. In this work, we assess the usefulness of such thermal treatment. In this communication, samples of pure iron cast ingots (maximum concentration of C = 31 ppm, N = 94 ppm, O = 31 ppm, S = 65 ppm) have been magnetically and structurally characterized. Progressive magnetic softening was observed upon successive annealing steps. These changes of the magnetic properties were ascribed to the relief of internal stresses. Various results, obtained by means of X-ray diffraction, electron microscope and precise determination of magnetization curve and hysteresis loop, will be presented and commented.
	Slides TU4PB02 [3.139 MB]

WEPPT003	Beam Optical Simulation in a Proposed Magnetic Einzel Lens	solenoid, ion, beam-transport, optics	323
	M.H. Rashid, A. Chakrabarti VECC, Kolkata, India
	Magnetic scalar potential and field distributions along the central axis of a magnetic einzel lens consisting of a pair of axisymmetric iron yoked anti-solenoids have been evaluated using a simple closed form of analytical expressions. The magnetic field distribution is used to track single charged particles as well as ion beam through lens segmentation method. The method facilitates in evaluation of optical properties as well as aberration coefficients of the lens. Application of such doublet solenoid lens in transporting low energy ion beam introduces minimal rotation of the beam as well as least entangling between transverse phase spaces of the beam.

WEPPT021	Columbus - A Simple Ion Source	ion-source, ion, cyclotron, proton	364
	M. J. Frank, E. Held, C.R. Wolf Ernes, Coburg, Germany
	An ion source provides a cyclotron with charged particles which can be accelerated by an electric field. The simpelst possibility is a thermionic ion-source. Electrons emitted from a white-hot tungsten filament, placed in a ceramic block of macor, are accelerated by a dc voltage of 100 - 150 V and constraint to a spiral path by the homogenous magnetic field of the cyclotron. They collide with hydrogen atoms and ionisize them. The ceramic block is covered by tube made of copper in which the ions raise up. They enter the gap between the dees through a small aperture in tube. The ion source is mounted under the dummy-dee, so its position can be changed to find the best place. The hydrogen gas is stored in a Hydro-stick, a small tube which contains 10 l of Hydrogen under a pressure of 10 bar. From here it enters the ion source by a mass-flow controller which enables accurate dosing.
	Poster WEPPT021 [1.640 MB]

WE3PB03	Space Charge Compensation Measurements in the Injector Beam Lines of the NSCL Coupled Cyclotron Facility	ion, space-charge, ECRIS, cyclotron	417
	D. Winklehner, D.G. Cole, D. Leitner, G. Machicoane, L. Tobos NSCL, East Lansing, Michigan, USA
	Space charge compensation is a well-known phenomenon for high current injector beam lines. For beam lines using mostly magnetic focusing elements and for pressures above 10^-6 mbar, compensation (neutralization) up to 98% has been observed. However, due to the low pressures required for the efficient transport of high charge state ions, ion beams in ECR injector lines are typically only partly neutralized and space charge effects are present. With the dramatic performance increase of the next generation Electron Cyclotron Resonance Ion Sources (ECRIS) it is possible to extract tens of mA of beams from ECR plasmas. Realistic beam transport simulations are important to meet the acceptance criteria of subsequent accelerator systems and have to include non-linear effects from space charge, but also space charge compensation. In this contribution we report on measurements of space charge compensation in the ECRIS low energy beam lines of the Coupled Cyclotron Facility at NSCL using a retarding field analyzer. Results are discussed and compared to simulations.
	Slides WE3PB03 [8.833 MB]

FR1PB05	In Memoriam: Henry G. Blosser	cyclotron, superconductivity, neutron, proton	473
	M.K. Craddock UBC & TRIUMF, Vancouver, British Columbia, Canada S.M. Austin, F. Marti NSCL, East Lansing, Michigan, USA
	Tribute to Henry Blosser
	Slides FR1PB05 [24.459 MB]

Paper

Title

Other Keywords

Page

TU2PB01

A Study of Multipacting Effects in Large Cyclotron Cavities by Means of Fully 3-Dimensional Simulations

simulation, cavity, cyclotron, RF-structure

142

C. Wang, B. Ji, Y. Lei, P.Z. Li, J.S. Xing, Z.G. Yin, T.J. Zhang
CIAE, Beijing, People's Republic of China
A. Adelmann, A. Gsell, M. Seidel
PSI, Villigen PSI, Switzerland

The field emission model and the secondary emission model, as well as 3D boundary geometry handling capabilities, are needed to efficiently and precisely simulate multipacting phenomena. These models have been implemented in OPAL, a parallel framework for charged particle optics in accelerator structures and beam lines. The models and their implementation are carefully benchmarked against a non-stationary multipacting theory. A dedicated multipacting experiment with nanosecond time resolution for the classic parallel plate geometry has also successfully shown the validity of OPAL model. Multipacting phenomena, in the CYCIAE-100 cyclotron, under construction at China Institute of Atomic Energy, are expected to be more severe during the RF conditioning process than in separate-sector cyclotrons. This is because the magnetic fields in the valley are stronger, which may make the impact electrons easier to reach energies that lead to larger multipacting probabilities. We report on simulation results for CYCIAE-100, which gives us an insight view of the multipacting process and help to develop cures to suppress these phenomena.

Slides TU2PB01 [7.012 MB]

TUPPT013

Simulation of Sufficient Spindle Cusp Magnetic Field for 28 GHz ECRIS

plasma, ECRIS, ion, ECR

180

M.H. Rashid, A. Chakrabarti
VECC, Kolkata, India

A cusp magnetic field (CMF) configuration is proposed for achieving more plasma confinement. It is an improved version of CMF compared to the classical one used earlier to design arbitrarily ECR ion source (ECRIS) of low frequency. The CMF has been reconfigured here adopting a simple, novel and cost-effective technique to shrink the loss area and to achieve denser plasma than in traditional ECRIS. The strength of the electron (plasma) confinement is demonstrated through electron simulations. It consists of a mid-iron disk, two end-plugs and a pair of superconducting magnet coils cooled by cryo-coolers. It is designed for high-B mode operation of the cusp ECRIS of as high as 28 GHz RF frequency for producing an intense beam of highly charged heavy ions. The electric current in the coil at the extraction end can be manipulated to optimize the operation to achieve high extracted beam current of highly charged ions.

TUPPT014

Characterization of the Versatile Ion Source (VIS) for the Production of Monocharged Light Ion Beams

plasma, ion, proton, ion-source

183

L. Celona, L. Calabretta, G. Castro, G. Ciavola, S. Gammino, D. Mascali, L. Neri, G. Torrisi
INFN/LNS, Catania, Italy
G. Castro
Universita Degli Studi Di Catania, Catania, Italy
F. Di Bartolo
INFN & Messina University, S. Agata, Messina, Italy

Funding: The support of the 5th National Committee of INFN is gratefully acknowledged.
The Versatile Ion Source (VIS) is an off-resonance Microwave Discharge Ion Source which produces a slightly overdense plasma at 2.45 GHz of pumping frequency. In the measurements carried out at INFN-LNS in the last two years, VIS was able to produce more than 50 mA of proton beams and He⁺ beams at 65 kV, while for H²⁺ a current of 15 mA was obtained. The know-how obtained with the VIS source has been useful for the design of the proton source of the European Spallation Source, to be built in Lund, Sweden, and it will be used also for other facilities. In particular, the design modifications of the VIS source under study at INFN-LNS, in order to use the new source as the injector of H²⁺ at the ISODAR facility, will be also presented.

TUPPT018

Critical Analysis of Negative Hydrogen Ion Sources for Cyclotrons

ion, ion-source, plasma, cyclotron

192

S. Korenev
Siemens Medical Solutions Molecular Imaging, Knoxville, TN, USA

The ion sources for cyclotrons based on negative hydrogen ions found applications as basic injectors for cyclotrons. The main important questions of negative hydrogen ion sources are following: i) method of production for negative hydrogen ions, ii) the extraction of ions and iii) separation of negative ions from electrons. Among of ion internal and external ion sources the common question is efficiency for production of negative hydrogen ions and increasing of kinetic energy of these ions. The critical analysis of different ions sources (PIG, Multicusps, etc.) is given. The comparison of these ion sources regarding applications for industrial cyclotrons for production of medical isotopes is presented in the paper.

Poster TUPPT018 [0.231 MB]

TUPPT019

Development Study of Penning Ion Source for Compact 9 MeV Cyclotron

ion, cathode, ion-source, plasma

195

Y.H. Yeon, J.-S. Chai, T.V. Cong, Kh.M. Gad, M. Ghergherehchi, S.Y. Jung, H.S. Kim, H.W. Kim, S.H. Kim, S.H. Lee, Y.S. Lee, X.J. Mu, S.Y. Oh, S. Shin
SKKU, Suwon, Republic of Korea

Funding: This research was supported by WCU (World Class University) program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology (R31-2008-10029).
Penning Ion Gauge(PIG) have been used in internal source for cyclotron. PIG source for internal source of 9 MeV cyclotron produces H⁻ ion. This source consists of cold cathode which discharges electrons for producing H⁻ ion and anode for making plasma wall. Cold cathode material tantalum was used for emitting electrons and tungsten copper alloy was used for anode. The size of PIG source is related to size of cyclotron magnet. Optimization of cathode and anode location and sizing were needed for simplifying this source for reducing the size of compact cyclotron. Transportation of electrons and number of secondary electrons has been calculated by CST particle studio. Motion of H2 gas has been calculated by ANSYS. Calculation of PIG source in 9 MeV cyclotron has been performed by using various chimneys with different size of expansion gap between the plasma boundary and the chimney wall. In this paper design process and experiment result is reported.

TUPSH005

Investigation of Cyclotron Carbon Foil Lifetime in Relation to its Thickness

proton, ion, cyclotron, radiation

227

J.-W. Kim, S. Hong, J.H. Kim
IBS, Daejeon, Republic of Korea
Y. Choi
Dongguk University, Gyeongju, Republic of Korea
Y.-S. Kim
Energy & Environmental System, Gyeongju, Republic of Korea

For extracting positive hydrogen atoms from accelerated negative ones, a thin carbon foil is usually used to stripe two electrons from negative atoms, which consists of one proton and two electrons traveling together up to 70MeV proton. The kinetic energy of electron is 38.13keV at the moment of stripping. The energy loss of protons and electrons in carbon foil could be estimated by the multiplication of stopping power (dE/dz) and the foil thickness where passing through. The stopping powers were estimated with 8.5 and 7.25 MeV/(g/cm²) for the proton and electron, respectively. In cyclotron the stripper is located in a strong magnetic field of ~Tesla, which makes electrons circular motion around the foil depositing all their kinetic energies into it. In this study, three different carbon foil thicknesses (200, 400, and 800 ug/cm²) were employed to investigate the correlation of foil temperature and their lifetime for the case of 1mA proton extraction. We are aiming the lifetime of a stripper foil to be as long as 2 weeks for irradiating protons onto an ISOL target. An effective lifetime of foils will be discussed as a function of a foil peak temperature.

TU3PB01

Bunch-Shape Measurements at PSI’s High-power Cyclotrons and Proton Beam Lines

proton, cyclotron, cathode, simulation

257

R. Dölling
PSI, Villigen PSI, Switzerland

Longitudinal-transversal 2D-density distributions of the bunched 2.2 mA CW proton beam can now be measured at the 13 last turns of the Injector 2 cyclotron, at several locations in the connecting beam line to the Ring cyclotron, at the first two turns of the Ring cyclotron (all at energies around 72 MeV), as well as behind the Ring cyclotron (at 590 MeV). In the large part, distributions can be taken from several angles of view, separated each by 45°. The measurement systems at our facility have evolved with time; this paper gives the present status, performance, limits and typical results. Due to the limited space, we refer in the large part to our previous publications [1, 2, 3] and concentrate on recent findings and measurements and ideas for next steps.

Slides TU3PB01 [9.393 MB]

TU3PB03

R&D of Helium Gas Stripper for Intense Uranium Beams

ion, target, acceleration, cyclotron

265

H. Imao, T. Dantsuka, M. Fujimaki, N. Fukunishi, H. Hasebe, O. Kamigaito, M. Kase, H. Kuboki, K. Kumagai, T. Maie, H. Okuno, T. Watanabe, Y. Watanabe, K. Yamada, Y. Yano
RIKEN Nishina Center, Wako, Japan

Intensity upgrade of uranium beams is one of the main concerns at the RIKEN Radioactive Isotope Beam Factory (RIBF). The lifetime problem of carbon-foil strippers due to the high energy loss of uranium beams around 10~MeV/u was a principal bottleneck for the intensity upgrade in the acceleration scheme at the RIBF. We have developed a re-circulating He-gas stripper as an alternative to carbon foils for the acceleration of high-power uranium beams. The new stripping system was actually operated in user runs with U³⁵⁺ beams of more than 1 puA. Electron-stripped U⁶⁴⁺ beams were stably delivered to subsequent accelerators without serious deterioration of the system for six weeks. The new He-gas stripper, which removed the primary bottleneck in the high-intensity uranium acceleration, greatly contributed the tenfold increase of the average output intensity of the uranium beams from the previous year.

Slides TU3PB03 [11.983 MB]

TU3PB04

TRIUMF Extraction Foil Developments and Contamination Reduction

extraction, scattering, simulation, TRIUMF

269

Y.-N. Rao, R.A. Baartman, I.V. Bylinskii, V.A. Verzilov
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
J.M. Schippers
PSI, Villigen PSI, Switzerland

Funding: TRIUMF receives funding via a contribution agreement through the National Research Council of Canada.
We made important developments on the extraction probes and stripping foils at TRIUMF. One of the issues we had was the ⁷Be contamination being observed near the 1A stripper, and relatedly, stripping foils warped or even broke during use. This was deemed due to over-heating in the foil and the frame. Another issue was related to the beam spills. Beam spills are primarily caused by the large angle scattering from the stripping foil. It was thus suggested that thinner foils be used to minimize the scattering. In view of these 2 issues, improvements were made such that (1) highly-orientated pyrolytic graphite foils, of thickness around 2 mg/cm², are now used; (2) Tantalum frame is now used in place of the previous stainless steel. These changes, plus additional heat relief features introduced, have resulted in 4 times longer lifetime with the foil, and 5 to 10 times reduction to the tank contamination level around the extraction probe. Also, these improvements have led to significantly reduced amount of beam spill monitor trips. This paper presents these developments and outcomes, including the simulations and calculations performed.

Slides TU3PB04 [4.798 MB]

TU4PB02

Structural and Magnetic Properties of Cast Iron for Cyclotrons

cyclotron, controls, induction, polarization

275

E. Forton, S. Zaremba
IBA, Louvain-la-Neuve, Belgium
E. Ferrara, F. Fiorillo, L. Martino, E. Olivetti, L. Rocchino
INRIM, Turin, Italy

At IBA, the steels used to build the magnets of the Cyclone 230 are cast on demand, using very strict criteria, casting procedure, requirements and quality control. Among the various steps performed at the foundry, a thermal annealing is made. In this work, we assess the usefulness of such thermal treatment. In this communication, samples of pure iron cast ingots (maximum concentration of C = 31 ppm, N = 94 ppm, O = 31 ppm, S = 65 ppm) have been magnetically and structurally characterized. Progressive magnetic softening was observed upon successive annealing steps. These changes of the magnetic properties were ascribed to the relief of internal stresses. Various results, obtained by means of X-ray diffraction, electron microscope and precise determination of magnetization curve and hysteresis loop, will be presented and commented.

Slides TU4PB02 [3.139 MB]

WEPPT003

Beam Optical Simulation in a Proposed Magnetic Einzel Lens

solenoid, ion, beam-transport, optics

323

M.H. Rashid, A. Chakrabarti
VECC, Kolkata, India

Magnetic scalar potential and field distributions along the central axis of a magnetic einzel lens consisting of a pair of axisymmetric iron yoked anti-solenoids have been evaluated using a simple closed form of analytical expressions. The magnetic field distribution is used to track single charged particles as well as ion beam through lens segmentation method. The method facilitates in evaluation of optical properties as well as aberration coefficients of the lens. Application of such doublet solenoid lens in transporting low energy ion beam introduces minimal rotation of the beam as well as least entangling between transverse phase spaces of the beam.

WEPPT021

Columbus - A Simple Ion Source

ion-source, ion, cyclotron, proton

364

M. J. Frank, E. Held, C.R. Wolf
Ernes, Coburg, Germany

An ion source provides a cyclotron with charged particles which can be accelerated by an electric field. The simpelst possibility is a thermionic ion-source. Electrons emitted from a white-hot tungsten filament, placed in a ceramic block of macor, are accelerated by a dc voltage of 100 - 150 V and constraint to a spiral path by the homogenous magnetic field of the cyclotron. They collide with hydrogen atoms and ionisize them. The ceramic block is covered by tube made of copper in which the ions raise up. They enter the gap between the dees through a small aperture in tube. The ion source is mounted under the dummy-dee, so its position can be changed to find the best place. The hydrogen gas is stored in a Hydro-stick, a small tube which contains 10 l of Hydrogen under a pressure of 10 bar. From here it enters the ion source by a mass-flow controller which enables accurate dosing.

Poster WEPPT021 [1.640 MB]

WE3PB03

Space Charge Compensation Measurements in the Injector Beam Lines of the NSCL Coupled Cyclotron Facility

ion, space-charge, ECRIS, cyclotron

417

D. Winklehner, D.G. Cole, D. Leitner, G. Machicoane, L. Tobos
NSCL, East Lansing, Michigan, USA

Space charge compensation is a well-known phenomenon for high current injector beam lines. For beam lines using mostly magnetic focusing elements and for pressures above 10^-6 mbar, compensation (neutralization) up to 98% has been observed. However, due to the low pressures required for the efficient transport of high charge state ions, ion beams in ECR injector lines are typically only partly neutralized and space charge effects are present. With the dramatic performance increase of the next generation Electron Cyclotron Resonance Ion Sources (ECRIS) it is possible to extract tens of mA of beams from ECR plasmas. Realistic beam transport simulations are important to meet the acceptance criteria of subsequent accelerator systems and have to include non-linear effects from space charge, but also space charge compensation. In this contribution we report on measurements of space charge compensation in the ECRIS low energy beam lines of the Coupled Cyclotron Facility at NSCL using a retarding field analyzer. Results are discussed and compared to simulations.

Slides WE3PB03 [8.833 MB]

FR1PB05

In Memoriam: Henry G. Blosser

cyclotron, superconductivity, neutron, proton

473

M.K. Craddock
UBC & TRIUMF, Vancouver, British Columbia, Canada
S.M. Austin, F. Marti
NSCL, East Lansing, Michigan, USA

Tribute to Henry Blosser

Slides FR1PB05 [24.459 MB]