| Paper | Title | Page |
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| MOPMB026 | Development of Transformative Cavity Processing - Superiority of Electropolishing on High Gradient Performance over Buffered Chemical Polishing at Low Frequency (322 MHz) | 145 |
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Funding: The work is supported by DOE Awards DE-SC0022994. A DOE grant R&D titled ¿Development of Transformative Preparation Technology to Push up High Q/G Performance of FRIB Spare HWR Cryomodule Cavities¿ is ongoing at FRIB. This R&D is for 2 years since September 2022. This project proposes four objectives: 1) Superiority on high gradient performance of electropolishing (EP) over buffered chemical polishing at low frequency (322 MHz), 2) High Qo performance by the local magnetic shield, 3) Development of HFQS-free BCP and, 4) Wet N-doping method. This paper will report the result of first object, and a local magnetic shield design and simulation to reduce the residual magnetic field < 0.1 mG in the vertical test Dewar, for the object 2. |
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| DOI • | reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB026 | |
| About • | Received ※ 14 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 08 July 2023 | |
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| MOPMB067 | Design of a Cathode Insertion and Transfer System for LCLS-II-HE SRF Gun | 267 |
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Funding: Work supported by cooperation project between MSU and HZDR RC113062 from the U.S. Department of Energy Office of Science under Cooperative Agreement DE-AC02-76SF00515. Superconducting radio frequency photo injectors (SRF gun) offer advantages for operating in continuous wave (CW) mode and generating high-brightness and high-current beams. A new SRF gun is designed as a low emittance photo injector for LCLS-II-HE and a prototype gun is currently being developed under collaboration between SLAC, FRIB, HZDR and ANL. The aim is to demonstrate stable CW operation at a cathode gradient of 30 MV/m. One of the crucial component for successful SRF gun operation is the photocathode system. The new SRF gun will adopt the HZDR-type cathode, which includes a cathode holder fixture (cathode stalk) developed by FRIB and a sophisticated cathode exchange system designed by HZDR. This innovative cathode insertion system ensures accurate, particle-free and warm cathode exchanges. A novel alignment process targets the cathode to the stalk axis without touching cathode plug itself. To commission the prototype gun, metallic cathodes will be used. A specifically designed vacuum system ensures vacuum pressure of 10-9 mbar for transport of a single cathode from the cleanroom to the gun. Thus maintaining cathode quality. |
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| DOI • | reference for this paper ※ doi:10.18429/JACoW-SRF2023-MOPMB067 | |
| About • | Received ※ 18 June 2023 — Revised ※ 23 June 2023 — Accepted ※ 26 June 2023 — Issue date ※ 18 July 2023 | |
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| TUPTB069 | Design and Tests of a Cathode Stalk for the LCLS-II-HE Low Emittance Injector SRF Gun | 589 |
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| A SRF gun can operate CW with a high gradient and ultra-low vacuum for high-quantum efficiency, low MTE photocathodes, useful features for delivery of high-brightness, high-repetition-rate beams. For these reasons, an SRF gun based photoinjector was chosen for a proposed Low Emittance Injector addition to the LCLS-II-HE facility, which will operate CW with bunch rates up to 1 MHz. For this injector, a prototype 185.7 MHz QWR gun is being developed in a collaborative effort among FRIB, HZDR, ANL and SLAC, with the goal of achieving a photocathode gradient of at least 30 MV/m. The photocathode is held by a coaxial fixture (cathode stalk) for thermal isolation from the cavity body. The system must allow for precise alignment of the photocathode, particle-free photocathode exchange, cryogenic (55-70 K) or warm (273-300 K) photocathode operating temperatures, and DC biasing to inhibit multipacting. A prototype cathode stalk has been built and bench tests are underway to validate the design. Measurements include RF power dissipation, DC bias hold-off, multipacting suppression and heat transfer effectiveness. This paper describes the cathode stalk design and the test results. | ||
| DOI • | reference for this paper ※ doi:10.18429/JACoW-SRF2023-TUPTB069 | |
| About • | Received ※ 03 July 2023 — Revised ※ 27 July 2023 — Accepted ※ 19 August 2023 — Issue date ※ 20 August 2023 | |
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