Design of a high repetition rate S-band photocathode gun

Abstract Photocathode RF guns have been developed in many laboratories for generating high quality electron beams for free-electron lasers based on linear accelerators. Such guns can generate electron beams with an exceptionally high peak current as well as a small transverse emittance. Their applications have been recently expanded for ultrafast electron diffraction, coherent terahertz radiation, and X-ray or γ ‐ ray radiation by Compton scattering. In this paper, we design an S-band normal-conducting gun with capabilities of high quality beam generation and high repetition rate operation. The RF design and thermal analysis of the gun cavity and coupler are introduced. Optimal position of the gun focusing solenoid for low emittance beam generation is found by performing particle tracking simulations. Then, the gun system is designed to be able to afford the optimal solenoid position. The cooling-water channel surrounding the gun cavity and coupler is designed and analyzed numerically. The pressure in the gun is simulated with a vacuum model containing the detailed inner structure of the gun. An injector for a free-electron laser application is designed by using this gun and the beam dynamics simulation is shown. A cold test with a prototype gun for confirmation of the RF design is reported.

[1]  R. Siemann,et al.  Experimental study of rf pulsed heating on oxygen free electronic copper , 2002 .

[2]  Jang-Hui Han.  Production of a sub-10 fs electron beam with107electrons , 2011 .

[3]  D. Meyerhofer,et al.  The design for the LCLS RF photoinjector , 1999 .

[4]  Henrik Loos,et al.  Commissioning the LCLS Injector , 2008 .

[5]  Wenhui Huang,et al.  Experimental demonstration of high quality MeV ultrafast electron diffraction. , 2009, The Review of scientific instruments.

[6]  Howard A. Padmore,et al.  Cathode R&D for future light sources , 2010 .

[7]  H. Ogawa,et al.  Development of Cs2Te photocathode rf gun system for compact THz SASE-FEL , 2008 .

[8]  U Schramm,et al.  Development of a high resolution and high dispersion Thomson parabola. , 2011, The Review of scientific instruments.

[9]  K. D. Friddell,et al.  First operation of a photocathode radio frequency gun injector at high duty factor , 1993 .

[10]  Thomas Weiland,et al.  Detailed characterization of electron sources yielding first demonstration of European X-ray Free-Electron Laser beam quality , 2010 .

[11]  P. Musumeci,et al.  High quality single shot diffraction patterns using ultrashort megaelectron volt electron beams from a radio frequency photoinjector. , 2010, The Review of scientific instruments.

[12]  J. Urakawa,et al.  100-femtosecond MeV electron source for ultrafast electron diffraction , 2009 .

[13]  Jacek Sekutowicz,et al.  RF gun design for the TESLA VUV free electron laser , 1997 .

[14]  Fumio Sakai,et al.  Quasi-monochromatic hard X-ray source via laser Compton scattering and its application , 2011 .

[15]  Single-side electron multipacting at the photocathode in rf guns , 2008 .

[16]  Jerome B. Hastings,et al.  Ultrafast Time-Resolved Electron Diffraction with Megavolt Electron Beams , 2006 .

[17]  S. Bryan,et al.  Storage ring vacuum system pressure modelling at Diamond , 2009 .

[18]  R. Ganter,et al.  Intrinsic emittance reduction of an electron beam from metal photocathodes. , 2010, Physical review letters.

[19]  Bruce E. Carlsten,et al.  New photoelectric injector design for the Los Alamos National Laboratory XUV FEL accelerator , 1989 .