| Paper | Title | Page |
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| MOP032 | High Pressure RF Cavity Test at Fermilab | 160 |
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Funding: Supported in part by DOE STTR grant DE-FG02-08ER86350 Operating a high gradient radio frequency cavity embedded in a strong magnetic field is an essential requirement for muon beam cooling. However, a magnetic field influences the maximum RF gradient due to focusing of dark current in the RF cavity. This problem is suppressed by filling the RF cavity with dense hydrogen gas. As the next step, we plan to explore the beam loading effect in the high pressure cavity by using a 400 MeV kinetic energy proton beam in the MuCool Test Area at Fermilab. We discuss the experimental setup and instrumentation. |
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| MOP046 | RF Breakdown Studies Using Pressurized Cavities | 184 |
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Funding: Supported in part by USDOE STTR Grant DE-FG02-08ER86352 and FRA DOE Contract DE-AC02-07CH11359 Many present and future particle accelerators are limited by the maximum electric gradient and peak surface fields that can be realized in RF cavities. Despite considerable effort, a comprehensive theory of RF breakdown has not been achieved, and mitigation techniques to improve practical maximum accelerating gradients have had only limited success. Recent studies have shown that high gradients can be achieved quickly in 805 MHz RF cavities pressurized with dense hydrogen gas without the need for long conditioning times, because the dense gas can dramatically reduce dark currents and multipacting. In this project we use this high pressure technique to suppress effects of residual gas and geometry found in evacuated cavities to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of radiofrequency and surface preparation. A 1.3-GHz RF test cell with replaceable electrodes (e.g. Mo, Cu, Be, W, and Nb) has been built, and a series of detailed experiments is planned at the Argonne Wakefield Accelerator. These experiments will be followed by additional experiments using a second test cell operating at 402.5 MHz. |
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| TUP083 | Phase and Frequency Locked Magnetrons for SRF Sources | 979 |
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Funding: Supported in part by STTR Grant DE-SC0002766 In order to make use of ferrite and/or garnet materials in the phase and frequency locked magnetron, for which Muons, Inc., received a Phase II award, materials must be tested in two orthogonal magnetic fields. One field is from the biasing field of the magnetron, the other from the biasing field used to control the ferrite within the anode structure of the magnetron. A test fixture was built and materials are being tested to determine their suitability. The status of those material tests are reported on in this paper. |
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| TUP092 | Multi-purpose 805 MHz Pillbox RF Cavity for Muon Acceleration Studies | 1003 |
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Funding: Supported by DOE grant DE-FG-08ER86352. An 805 MHz RF pillbox cavity has been designed and constructed to investigate potential muon beam acceleration and cooling techniques. The cavity can operate in vacuum or under pressure to 100 atmospheres, at room temperature or in an LN2 bath at 77 K. The cavity is designed for easy assembly and disassembly with bolted construction using aluminum seals. The surfaces of the end walls of the cavity can be replaced with different materials such as copper, aluminum, beryllium, or molybdenum, and with different geometries such as shaped windows or grid structures. Different surface treatments such as electro polished, high-pressure water cleaned, and atomic layer deposition are being considered for testing. The cavity has been designed to fit inside the 5-Tesla solenoid in the MuCool Test Area at Fermilab. Performance of the cavity, including initial conditioning and operation in the external magnetic field will be reported. |
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