Advances in the Current and Future X-ray Sources

by Kwang-Je Kim (ANL)

Thursday Dec 5, 2019, 3:30 PM → 5:00 PM Pacific/Honolulu

Rm 112 (WAT Hall)

X-rays from synchrotron radiation (SR) and free-electron lasers (FELs) have huge impact in the recent advances in various areas of science and technology. Having gone through several generations of advances, the research facilities based on SR are currently at the 4th generation stage, thus referred to as 4GSRs. A 4GSR employs spontaneous radiation from undulators installed in an “ultimate storage ring”, in which the phase space area of the electron beam is “diffraction limited” in the soft X-ray spectrum. In an X-ray FEL (XFEL), the spontaneous emission is self-amplified in a long undulator by a factor about a million, giving rise to intense, quasi-coherent radiation. The brightness of the first generation XFELs driven by Cu-linac is about the same as that of 4GSRs. We are about to witness the advent of XFELs driven by super-conducting RF (SCRF) linacs with a repetition rate higher by three to four orders of magnitudes than that from Cu-linacs, and thus proportionally higher brightness.  An SCRF linac operating in CW mode can also drive an X-ray FEL oscillator (XFELO), which can potentially deliver brightness higher by three orders of magnitude due to its extremely narrow spectral bandwidth.  An R&D program by an ANL-SLAC collaboration is launched recently to be carried out in the undulator hall of the LCLS using double electron bunches from the SLAC Cu-linac to test the first two-pass amplification in an XFELO.