Experiments: Approved - Nonactive

Coherent Smith-Purcell Radiation as an Electron Bunch Diagnostic Technique

AE21. Spokesperson: D. Nguyen, LANL.

Abstract We have designed a new technique for measuring subpicosecond electron bunch lengths using coherent Smith-Purcell radiation. This new diagnostic technique involves passing the electron beam in close proximity of a grating with period comparable to the electron bunch length. The emitted Smith-Purcell radiation will have a coherent component whose angular position and distribution are directly related to the electron bunch length and longitudinal profile, respectively. This new diagnostic technique is inherently simple, inexpensive and non-intercepting. We show that the new technique is also scaleable to femtosecond regime. grating. A collimator is used to confine the beam to a well-defined height above the grating. Two mirrors, one cylindrical and one spherical, act like a 90° paraboloid and focus the coherent SPR to a spot at the detector located outside the diagnostic module. The coherent SPR signals at different angles, provided they are within the acceptance angle of the two curved mirrors, are focused to different positions at the focal plane. A detector array located at the focal plane of the curved mirrors is used to cover a range of observation angles at any given time. Alternatively, the two curved mirrors can be rotated together with the pivot at the grating to cover a larger range of angles.

Selected publications:

Fundamental idea -

PAC'97 paper, ELECTRON BUNCH LENGTH DIAGNOSTIC WITH COHERENT SMITH-PURCELL RADIATION.

for information contact: Dinh Nguyen [dcnguyen@lanl.gov]

Last Modified: December 3, 2007
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