Pushing the Limits of Bright Electron Beams

Date(s) - Jan 19 2018
10:00 AM - 11:00 AM

Kavli Auditorium, Building 51, Room 102


Dr. SiddharthKarkare

Lawrence Berkeley National Lab

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.