Potential production of ultrashort electron bunches with the Advanced Photon Source linac

Abstract

With the recent addition of a chicane bunch compressor to the Advanced Photon Source (APS) linac, it may now be possible to create ultrashort electron bunches, with rms bunch lengths on the order of 10 fs and peak currents of several hundred amperes. Although such bunches are too short to be useful for free-electron-laser-related work, they would still provide a potential source of short-pulse spontaneous radiation, either from an undulator or a bending magnet. The APS linac features a high-brightness thermionic rf gun that delivers a beam to the linac via an alpha magnet. This setup provides a first stage of bunch compression at an energy of about 3 MeV, as well as permitting elimination of the low-energy tail using a scraper in the alpha magnet. In simulations, this beam has been further compressed using the chicane bunch compressor at 150 MeV. Scrapers in the chicane are used to aid in the production of a clean, short pulse. This paper discusses the results of these simulations, including jitter sensitivity and the effects of coherent synchrotron radiation and wakefields.