Demonstration of sub-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>GV</mml:mi><mml:mo>/</mml:mo><mml:mi mathvariant="normal">m</mml:mi></mml:mrow></mml:math> accelerating field in a photoemission electron gun powered by nanosecond <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>X</mml:mi></mml:math>-band radio-frequency pulses
Wei Hou Tan, Sergey Antipov, Darrell Doran, Gwanghui Ha, Chunguang Jing, Ernest Knight, Sergey Kuzikov, W. Liu, Xueying Lu, P. Piot, John Power, Jiahang Shao, Charles Whiteford, Eric Wisniewski
Abstract
Radio-frequency (rf) photoemission electron guns operating at higher accelerating gradients offer a pathway to produce brighter electron bunches. Brighter beams are expected to revolutionize many areas of science: they could form the backbone of next-generation compact x-ray free-electron lasers or provide coherent ultrafast quantum electron probes. We report on the experimental demonstration of an rf photoemission electron source supporting an accelerating field close to $400\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ at the photocathode surface without major rf breakdown or significant dark current over a 3-week experimental run. This unprecedented gradient was achieved by operating the gun in a new regime with short rf pulses, $\ensuremath{\sim}9\text{ }\text{ }\mathrm{ns}$ $X$-band (11.7 GHz). The demonstrated paradigm provides a viable path to form relativistic electron beams with unprecedented brightness.