2011 Particle Accelerator Conference - List of Authors (Rose, D.)

Paper	Title	Page
MOP046	RF Breakdown Studies Using Pressurized Cavities	184
	R. Sah, A. Dudas, R.P. Johnson, M.L. Neubauer Muons, Inc, Batavia, USA M. BastaniNejad, A.A. Elmustafa Old Dominion University, Norfolk, Virginia, USA J.M. Byrd, D. Li LBNL, Berkeley, California, USA M.E. Conde, W. Gai ANL, Argonne, USA A. Moretti, M. Popovic, K. Yonehara Fermilab, Batavia, USA D. Rose Voss Scientific, Albuquerque, New Mexico, USA
	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.

Paper

Title

Page

RF Breakdown Studies Using Pressurized Cavities

184

R. Sah, A. Dudas, R.P. Johnson, M.L. Neubauer
Muons, Inc, Batavia, USA
M. BastaniNejad, A.A. Elmustafa
Old Dominion University, Norfolk, Virginia, USA
J.M. Byrd, D. Li
LBNL, Berkeley, California, USA
M.E. Conde, W. Gai
ANL, Argonne, USA
A. Moretti, M. Popovic, K. Yonehara
Fermilab, Batavia, USA
D. Rose
Voss Scientific, Albuquerque, New Mexico, USA

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.