Abstract
Field emission from a solid metal surface, the precursor of rf breakdown, has been continuously studied for a century from macroscopic to atomic scales. However, many fundamental questions are yet to be answered, especially in rf case. Uncontrollable field emission position is one of the main barriers on the path to explore its nature. This chapter introduces a novel method to control the location of field emission and that of rf breakdown with a pin cathode. The study has been conducted on an L-band single-cell photocathode rf gun at the Argonne Wakefield Accelerator facility. The first part is to study the evolution of field emission during the rf conditioning period. The experimental results suggest there is an rf breakdown threshold of the maximum electric field on copper surface. The second part is to examine the localized field emission dependence on global parameters. The stored energy of the rf gun was changed by adjusting the longitudinal position (distance between the cathode base and the gun back surface) of the cathode while the applied electric field on the cathode tip was kept constant. A strong dependence of field emission on the stored energy has been observed which implies that under certain circumstances, a localized field emission may be significantly altered by the global parameters in a system.
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Shao, J. (2018). Experimental Research of Pin Cathode. In: Investigations on rf breakdown phenomenon in high gradient accelerating structures. Springer Theses. Springer, Singapore. https://doi.org/10.1007/978-981-10-7926-9_3
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DOI: https://doi.org/10.1007/978-981-10-7926-9_3
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