Development of a Laser-Driven Photocathode Radio Frequency Electron Gun System at NSRRC

Wai-Keung Lau^1*, An-Ping Lee¹, Ming-Chang Chou¹, Hsin-Pai Hsueh¹

¹Light Source Division, National Synchrotron Radiation Research Center, Hsinchu, Taiwan

* Presenter:Wai-Keung Lau, email:wklau@nsrrc.org.tw

High brightness electron guns are crucial sub-systems of many large scale facilities such as linear colliders, x-ray free electron lasers (FEL) and ultra-low emittance synchrotron radiation sources. A laser-driven photo-cathode rf gun has the capability to generate low emittance electron beam of high charge density and its beam temporal structure is controllable by the drive laser. Due to their superior performance and flexibility, photocathode rf guns became the most employed technology among other means of high brightness electron beam generation. In addition, its compact footprint enables also the development of laboratory-scale equipment like inverse Compton scattering x-ray/γ-ray sources, ultrafast electron diffraction (UED) as well as intense coherent THz radiation sources. In this report, the efforts of developing a high brightness electron linear accelerator (linac) test system that based on photo-cathode rf gun technology at NSRRC will be presented. This test linac has been operational regularly since 2017 for novel light source development and testing of accelerator key components. Generation of intense coherent THz radiation of 20 μJ pulse energy from a 10-cm period planar undulator has been demonstrated. Investigation of the possibility of using this linac to drive a 266-nm UV laser seeded VUV FEL is in progress.

Keywords: High brightness electron guns, Linear accelerator, Coherent THz radiation, Free electron lasers