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| TUPAL062 | Recent Developments for Cyclotron Extraction Foils at TRIUMF | 1159 |
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Funding: Funded under a contribution agreement with NRC (National Research Council Canada). The TRIUMF 500 MeV H− cyclotron employs stripping foils to extract multiple beams for different experimental programs. The upgrades in foil material and foil holders lead to significant improvements in beam quality and foil life time, as well as reduction of Be-7 contamination originated in the foils. Thus, an accumulated beam charge extracted with a single foil increased from ~60 mA·hours to more than 500 mA·hours. A key role that lead to these advances was an understanding of the foil heating mechanism, major contribution to which is paid by the power deposition from electrons stripped by the foil. To further diminish this effect, we recently introduced a foil tilt from the vertical orientation that allows stripped electrons fast escape from the foil, well before losing their original momentum through the heat deposition. Other improvements were related to operational issues. Introduction of a "combo" foil consisting of wide portion and thin wire allowed both high and low intensity beam extraction without foils sacrifice. Deploying a wedge foil for extraction at 100 MeV helped reduction of beam intensity instabilities caused by beam vertical size and position fluctuations. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL062 | |
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| TUPMK011 | Single Ring Permanent Magnet Lens | 1513 |
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Funding: TRIUMF receives its funding from the National Research Council of Canada. A permanent magnet lens has been designed to be a non-powered alternative to solenoids for low energy beam transport. The lens consists of a single ring of 12 sectors, each sector with poles directed inward. This forms an axial field that reverses sign at the midpoint, somewhat like two opposing short solenoids. It is similar to the Iwashita lens* but consists of only one ring, not two. A prototype lens optimized to decrease the magnetic material required while also reducing aberration, has been built and tested for a 25 keV H-minus beam. Emittance figures measured downstream of the lens are compared with theory. * Y. Iwashita, "Axial Magnetic Field Lens with Permanent Magnet", Proc. PAC 1993, p.3154. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMK011 | |
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| THPAK104 | New Proton Driver Beamline Design for ARIEL* Project at TRIUMF** | 3473 |
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Funding: ∗ Capital funding from CFI (Canada Foundation for Innovation). ** Funded under a contribution agreement with NRC (National Research Council Canada). The new radioisotope facility at TRIUMF, ARIEL, under construction, comprises two primary driver beams: 50 MeV electrons from the SC linac and 480 MeV protons from the main TRIUMF cyclotron. New 80 m long proton beam line will transport up to 100 microamps beam from existing cyclotron extraction port to an ISOL target station. H− cyclotron stripping foil extraction allows to feed this additional user simultaneously with 3 present different experimental programs. Distinctive features of the new beam line include: a) compensation of the cyclotron energy dispersion; b) low-loss (< 1 nA/m) beam transport after a collimator dedicated to remove the beam halo produced by large-angle scattering in the extraction foil; c) broad range of beam size variability at the production target by applying beam rastering at 400 Hz; d) sharing the same tunnel with electron beam line that requires unique beam loss protect system. Details of beam optics design as well as beam instrumentation are discussed in the paper. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK104 | |
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| THPAK109 | Improved Simulation for Centre Region of TRIUMF 500 MeV Cyclotron with Space Charge | 3489 |
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Funding: TRIUMF receives federal funding via a contribution agreement through the National Research Council of Canada The TRIUMF 500 MeV cyclotron delivered routinely a total current up to 200 μA protons for 15 years till 2001. Since 2002, developments towards 300 μA total extraction became compelling because of the ISAC expansion. To meet future requirements (for addition of a new beam-line), a total extraction of 310 − 450 μA shall be envisioned. With such an increase of beam current, the space charge effect becomes a major concern in the centre region, as it limits the maximum amount of beam current achievable out of the machine. Therefore, numerical simulation on beam orbits with the space charge force has has been initiated, starting from the injection gap. This study is focused on the beam bunches which are very long compared with transverse size (because TRIUMF extraction is by stripping of H-minus and separated turns are not required). In order to achieve an improved understanding of the space charge effect, we worked to validate the simulations performed without and with the space charge force, using realistic centre region geometry. Our goal is to work out the space charge limits and their dependence upon the bunchers, rf voltage, and matching. In this paper we present our recent progress in this study. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK109 | |
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| THPAK110 | Correction of νr-νz=1 Resonance in TRIUMF Cyclotron | 3492 |
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Funding: TRIUMF receives federal funding via a contribution agreement through the National Research Council of Canada The second order linear coupling resonance nur-nuz=1 is driven by an asymmetry in the median plane of the cyclotron due to presence of the first harmonic in Br component. In TRIUMF cyclotron, this resonance is encountered at about 166 MeV and 291 MeV, where nur=1.2 and nuz=0.2. When the beam is off-centered radially to pass through this resonance, the radial oscillation gets converted into vertical oscillation, which can cause beam loss to occur, though these loss modes do not reduce the machine transmission under normal operation. In this paper, we present the results of simulations and measurements that we have performed to correct this resonance by using the existing harmonic coils. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK110 | |
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| THPAK111 | Envelope Calculations on the Ion Beam Injection and Extraction of CANREB EBIS | 3496 |
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| An electron beam ion source (EBIS) is being developed as a charge state breeder for the production of highly charged ions in the CANREB (CANadian Rare isotope facility with Electron Beam ion source) project at TRIUMF. The multiple tunable electrodes of the EBIS, coupled with the necessity of directing both an electron beam and an ion beam of varying charge, impose a challenging task for the optimization of the beam optics. With this in mind, beam envelope simulations have been performed to determine the acceptance of the EBIS and the emittance of the extracted ion beam. The electric field of the different EBIS electrodes were modelled using finite element analysis software and the envelope simulations were executed using beam envelope code TRANSOPTR. Preliminary results show envelope calculation as a viable candidate for tuning the injection and extraction optics of the EBIS. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK111 | |
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| THPML079 | Multipole Tuning Algorithm for the CANREB HRS at TRIUMF | 4836 |
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| The TRIUMF CANadian Rare isotope facility with Electron Beam ion source (CANREB) High Resolution Separator (HRS) has been designed to separate rare isotopes with mass/charge differences of only one part in 20,000 for beams with transverse emittances of 3 μm. To reach this resolution, high-order aberrations must be corrected using a multipole corrector. From experience, tuning such a multipole is very challenging. The unique geometry of our multipole motivated a novel tuning method based on determining the desired pole voltages directly from measured emmitance. This novel tuning algorithm is presented alongside a web application which has been developed in anticipation of the commissioning of the HRS. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML079 | |
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| THPML122 | Beta-SRF - A New Facility to Characterize SRF Materials near Fundamental Limits | 4961 |
| SUSPL077 | use link to see paper's listing under its alternate paper code | |
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Funding: Natural Sciences and Engineering Research Council of Canada (NSERC) & UBC (NSERC) IsoSiM Program Demands of CW high-power LINAC require SRF cavities operating at the frontier of high accelerating gradient and low RF power dissipation, i.e. high quality factor (Q0). This requirement poses a challenge for standard surface treatment recipes of SRF cavities. In a recent breakthrough, elliptical SRF cavities doped with Nitrogen have been shown to improve Q0 by a factor of 3, close to the fundamental SRF limit. The fundamental mechanisms at microscopic level and optimum doping recipe, however, have still not fully been understood. Materials other than Nb have also been proposed for SRF cavities to overcome the fundamental limit already reached with Nitrogen doping, e.g. Nb3Sn, MgB2, and Nb-SIS multilayer. At TRIUMF, a unique experimental facility is currently being developed to address these issues. This facility will be able to probe local surface magnetic field in the order of the London Penetration Depth (several tens of nm) via \beta decay detection of a low-energy radioactive ion-beam. This allows depth-resolution and layer-by-layer measurement of magnetic field shielding effectiveness of different SRF materials at high-parallel field (up to 200 mT). Design and current development of this facility will be presented here, as well as commissioning and future measurements strategies for new SRF materials. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML122 | |
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