Optical Design Considerations Relevant to Reflective UV Launch Gratings for Photocathode Irradiation

Bolton, Paul

关键词: DESIGN;    DIFFRACTION GRATINGS;    PERFORMANCE;    ELECTRON BEAMS;    BEAM BUNCHING;    IRRADIATION;    LASERS;    PHOTOCATHODES;    PULSE TECHNIQUES XFEL;   

DOI  :  10.2172/1000321
RP-ID  :  SLAC-TN-10-079
PID  :  OSTI ID: 1000321
Others  :  TRN: US1100083

学科分类：核物理和高能物理

美国|英语

来源: SciTech Connect

【 摘 要 】

The characteristics of photoelectron microbunches emitted from a photocathode in response to laser irradiation determine many of the incident laser pulse requirements. RF photocathode designs based on grazing incidence of the irradiation benefit from the removal of launch optics from the electron beamline and enhanced absorption at Brewster angles. However, this also introduces two well known complexities in the laser pulse 'launch' requirements: (i) a transverse spatial anamorphism to guarantee that the projected transverse spatial profile of the irradiation is circular (in the plane of the photocathode) and (ii) a 'time slew' or tilted amplitude front on the laser pulse that is incident on the photocathode to guarantee that the temporal (longitudinal) profiles are synchronous across the entire transverse irradiation profile in the photocathode plane. A single diffraction grating can be used to fulfill these combined requirements. This reported work focuses on grating behavior only. It does not address imaging requirements associated with relayed optical transport from the grating to the photocathode. Because the grating is a highly dispersive optical element by design, the dispersive aspects of all launch requirements are important.