11

A Microwave Beam Monitoring System for Direct Measurement of Ultra Short Electron Bunches--Haimson Research Corporation, 3350 Scott Boulevard, Building 60, Santa Clara, CA  95054-3104; 408-988-6007

Dr. Jacob Haimson, Principal Investigator, Haimson@aol.com 

Ms. Beverly Mecklenburg, Business Official, Haimson@aol.com 

DOE Grant No. DE-FG03-01ER83247

Amount:  $749,913

Recent advances in high frequency linear accelerator technology have resulted in steady-state electron beams having RF bunch widths of 50 to 200 femtoseconds, considerably shorter than the practical resolution of fast diagnostic streak camera systems.  Therefore, the accurate measurement of the longitudinal phase space of ultra short bunches using microwave power would be highly advantageous and economically attractive, especially if the complexity, sensitivity, and a priori assumptions associated with alternative electro-optic methods could be avoided.  This project will develop a circularly-polarized, beam-deflecting microwave structure that provides a highly amplified image display of the electron bunch, with phase and energy distributions projected in orthogonally-differentiated azimuthal and radial directions.  Combining such a microwave structure with a beam focusing element offers a simple on-line diagnostic for the definitive measurement of ultra short RF bunches.  During Phase I, a detailed microwave and beam optics analysis was performed, and the results indicated that, with an emittance-limited beam image focused at the analyzing plane, a dual-input circularly-polarized microwave structure could produce phase resolution less than 1 degree (100 femtoseconds at 17 gigahertz).  In addition, the design parameters of all major components were established, and an overall layout drawing was prepared to show how the bunch monitoring system could be integrated into an existing accelerator test facility.  Phase II will fabricate the microwave beam deflector and the associated rectangular waveguide network, the beam focusing system and diagnostic chamber, and the peripheral subsystems.  The electro bunch diagnostic equipment will be integrated into an existing 17 gigahertz linear accelerator test facility, and high power beam tests will be conducted to evaluate the performance of the overall system.

Commercial Applications and Other Benefits as described by the awardee:  The technology should result in an on-line beam monitoring system capable of accurately evaluating the RF bunch performance of advanced accelerator systems.  The attainment of very short RF bunches should be of considerable interest for free electron lasers, wakefield accelerators, linear colliders, and the generation of intense coherent radiation.