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| MOPAB384 | Nb3Sn Coating of Twin Axis Cavity for Accelerator Applications | 1175 |
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Funding: Research supported by DOE Office of Science Accelerator Stewardship Program Award DE- SC0019399. Partially authored by Jefferson Science Associates under contract no. DEAC0506OR23177 A Superconducting twin axis cavity consisting of two identical beam pipes that can accelerate and decelerate beams within the same structure has been proposed for the Energy Recovery Linac (ERL) applications. There are two niobium twin axis cavities at JLab fabricated with the intention of later Nb3Sn coating and now we are progressing to coat them using vapor diffusion method. Nb3Sn is a potential alternate material for replacing Nb in SRF cavities for better performance and reducing operational costs. Because of advanced geometry, larger surface area, increased number of ports and hard to reach areas of the twin axis cavities, the usual coating approach developed for typical elliptical single-axis cavities must be evaluated and requires to be adjusted. In this contribution, we report the first results from the coating of a twin axis cavity and discuss current challenges with an outlook for the future. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB384 | |
| About • | paper received ※ 19 May 2021 paper accepted ※ 24 May 2021 issue date ※ 27 August 2021 | |
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| MOPAB396 | Measurements of Magnetic Field Penetration in Superconducting Materials for SRF Cavities | 1208 |
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Funding: This work is supported by NSF Grants PHY-1734075 and PHY-1416051, and DOE Award DE-SC0010081 and DE-SC0019399 Superconducting radiofrequency (SRF) cavities used in particle accelerators operate in the Meissner state. To achieve high accelerating gradients, the cavity material should stay in the Meissner state under high RF magnetic field without penetration of vortices through the cavity wall. The field onset of flux penetration into a superconductor is an important parameter of merit of alternative superconducting materials other than Nb which can enhance the performance of SRF cavities. There is a need for a simple and efficient technique to measure the onset of field penetration into a superconductor directly. We have developed a Hall probe experimental setup for the measurement of the flux penetration field through a superconducting sample placed under a small superconducting solenoid magnet which can generate magnetic fields up to 500 mT. The system has been calibrated and used to measure different bulk and thin film superconducting materials. This system can also be used to study SIS multilayer coatings that have been proposed to enhance the vortex penetration field in Nb cavities. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB396 | |
| About • | paper received ※ 19 May 2021 paper accepted ※ 23 June 2021 issue date ※ 30 August 2021 | |
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| TUPAB344 | Evaluation of Anisotropic Magnetoresistive (AMR) Sensors for a Magnetic Field Scanning System for SRF Cavities | 2304 |
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Funding: Work supported by NSF Grant 100614-010. G. C. is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. One of the significant causes of residual losses in superconducting radio-frequency (SRF) cavities is trapped magnetic flux. The flux trapping mechanism depends on many factors that include cool-down conditions, surface preparation techniques, and ambient magnetic field orientation. Suitable diagnostic tools are not yet available to quantitatively correlate such factors’ effect on the flux trapping mechanism. A magnetic field scanning system (MFSS) consisting of AMR sensors, fluxgate magnetometers, or Hall probes is recently commissioned to scan the local magnetic field of trapped vortices around 1.3 GHz single-cell SRF cavities. In this contribution, we will present results from sensitivity calibration and the first tests of AMR sensors in the MFSS. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB344 | |
| About • | paper received ※ 19 May 2021 paper accepted ※ 09 June 2021 issue date ※ 29 August 2021 | |
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| WEPAB092 | Redesign of the Jefferson Lab -300 kV DC Photo-Gun for High Bunch Charge Operations | 2802 |
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Funding: The U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177, JSA initiatives fund program and Laboratory Directed Research and Development program. Production of high bunch charge beams for the Electron-Ion Collider (EIC) is a challenging task. High bunch charge (a few nC) electron beam studies at Jefferson Lab using an inverted insulator DC high voltage photo-gun showed evidence of space charge limitations starting at 0.3 nC, limiting the maximum delivered bunch charge to 0.7 nC for beam at -225 kV, 75 ps (FWHM) pulse width, and 1.64 mm (rms) laser spot size. The low extracted charge is due to the modest longitudinal electric field (Ez) at the photocathode leading to beam loss at the anode and downstream beam pipe. To reach the few nC high bunch charge goal, and to correct the beam deflection exerted by the non-symmetric nature of the inverted insulator photo-gun the existing photo-gun was modified. This contribution discusses the electrostatic design of the modified photo-gun obtained using CST Studio Suite’s electromagnetic field solver. Beam dynamics simulations performed using General Particle Tracer (GPT) with the resulting electrostatic field map obtained from the modified electrodes confirmed the validity of the new design. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB092 | |
| About • | paper received ※ 20 May 2021 paper accepted ※ 02 June 2021 issue date ※ 17 August 2021 | |
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| MOPAB393 | Design of an RF-Dipole Crabbing Cavity System for the Electron-Ion Collider | 1200 |
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| The Electron-Ion Collider requires several crabbing systems to facilitate head-on collisions between electron and proton beams in increasing the luminosity at the interaction point. One of the critical rf systems is the 197 MHz crabbing system that will be used in crabbing the proton beam. Many factors such as the low operating frequency, large transverse voltage requirement, tight longitudinal and transverse impedance thresholds, and limited beam line space makes the crabbing cavity design challenging. The rf-dipole cavity design is considered as one of the crabbing cavity options for the 197 MHz crabbing system. The cavity is designed including the HOM couplers, FPC and other ancillaries. This paper presents the detailed electromagnetic design, mechanical analysis, and conceptual cryomodule design of the crabbing system. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB393 | |
| About • | paper received ※ 26 May 2021 paper accepted ※ 02 June 2021 issue date ※ 26 August 2021 | |
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| WEPAB093 | Space Charge Effects in Low Energy Magnetized Electron Beam | 2806 |
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Funding: This work is supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177 and Laboratory Directed Research and Development program. Magnetized electron cooling is one of the major approaches towards obtaining the required high luminosity in the proposed Electron-Ion Collider (EIC). In order to increase the cooling efficiency, a bunched electron beam with a high bunch charge and high repetition rate is required. At Jefferson Lab, we generated magnetized electron beams with high bunch charge using a new compact DC high voltage photogun biased at -300 kV with bialkali-antimonide photocathode and a commercial ultra-fast laser. This contribution discusses how magnetization affects space charge dominated beams as a function of magnetic field strength, gun high voltage, and laser pulse width, and spot size in comparison with simulations performed using General Particle Tracer. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB093 | |
| About • | paper received ※ 19 May 2021 paper accepted ※ 08 June 2021 issue date ※ 02 September 2021 | |
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| THPAB025 | A Proposed Beam-Beam Test Facility COMBINE | 3802 |
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Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, license to publish or reproduce this manuscript. The COmpact Machine for Beam-beam Interactions in Non-Equilibrium systems (COMBINE) is a proposed, dedicated, beam-beam test facility. The base design would make use of a pair of identical octagonal rings (2.5 meters per side) one rotated 180 degrees from the other, meeting at their common interaction point. These would be fed by an electron gun producing up to 125 keV electrons. The low energy will allow for beam-beam tune shifts commensurate with existing colliders, some linac-ring type systems, and will also allow for an exploration of the predicted effects of gear-changing, which would be performed using a variable pathlength scheme. The low energy, and small size will allow for cost effective research, simulation code benchmarking, as well as training opportunities for students. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB025 | |
| About • | paper received ※ 20 May 2021 paper accepted ※ 01 September 2021 issue date ※ 16 August 2021 | |
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