Wednesday, February 14, 2018 at 3:30pm
Physical Sciences Building, 401
245 East Avenue
Title: Pushing the Limits of Bright Electron Beams
Abstract: Electron beam brightness, the charge density per unit phase space, is the critical figure of merit which limits the performance of most electron beam applications ranging from multi-GeV-km-scale applications like X-ray free electron lasers and particle colliders, to few-100-keV-few-meters-scale long applications such as ultrafast electron diffraction and compact x-ray sources.
In this talk, first, I will discuss the limits of electron beam brightness and show how the brightest electron sources (photoinjectors) today are limited by the ability of materials to photo-emit electrons with minimal transverse momentum spread. I discuss how various factors such as surface non-uniformities, electron heating and electronic band-structure affect the transverse momentum spread of photoemitted electrons and how the design of new photoinjectors needs to be informed by these effects. Then I present our efforts to search for and develop novel materials to minimize the transverse momentum spread increasing the electron beam brightness by up to two orders of magnitude. Finally, I show how minimizing the transverse momentum leads to a new regime in beam dynamics where the disordered granularity in the electron beam limits the brightness.
Simulcast at Cornell: https://cornell.zoom.us/j/342920767