Invited Paper AS-WeA1
Albert Nerken Award Lecture - Photocathodes for Future X-ray Light Sources

Wednesday, October 30, 2013, 2:00 pm, Room 204

Synchrotron sources of x-rays have revolutionized many areas of materials science. From the 1^st generation synchrotrons of the 1970s to the 3^rd generation of storage ring-based machines of today, the brightness has increased by around 6 orders of magnitude. Measurements that were formerly done at the mm spatial scale have become routine at sub 100 nm spatial resolution. New methods such as ptychography are taking us now to nm resolution. Storage rings can be pushed further, and sources with full transverse coherence are planned, increasing the brightness again b y 2 - 3 orders of magnitude. Over the last 10 years, there has been a parallel development of Free Electron Lasers (FELs), that push the peak brightness up again by a further factor of 10¹⁰ and reduce pulse length to the few fsec range. These machines complement quasi cw synchrotrons and are the tool of choice for studying ultrafast dynamics. I will briefly review some of these historical developments, and then focus on a key enabling technology for MHz repetition rate FELs, the production of ultrafast pulses of electrons from photocathodes. I will review our current work in the synthesis of high efficiency alkali antimonide based cathodes, and cathodes based on non-linear photoemission from plasmonic systems.