The role of high-gradient and X-band technology is expanding steadily, with applications at a surprisingly wide range of scales. The April 2018 issue of the CERN Courier features an article on X-band technology: ''High-gradient X-band technology: from TeV colliders to light sources and more'' by Walter Wuench (CERN).
The article showcase how the demanding and creative environment of fundamental science serve as a fertile breeding ground for new technologies, in particular how technologies developed for CLIC show promise for smaller accelerators for applications outside high-energy physics. Several different XFEL applications are discussed: compact linacs and advanced diagnostics for photon sources (XFEL and Compton), medical applications (proton acceleration and very high energy electron therapy), and linacs to test advanced acceleration techniques.
Simulation of the field inside an RF deflector used to measure the bunch characteristics at XFELs, credit: A Grudiev