An international team presents the functional principle of a new source of synchrotron radiation in Nature Communications Physics. Steady-state microbunching (SSMB) allows to build efficient and powerful radiation sources for coherent UV radiation in the future. This is very attractive for applications in basic research as well in the semiconductor industry.
When ultrafast electrons are deflected, they emit light – synchrotron radiation. This is used in so called storage rings in which magnets force the particles onto a closed path. This light is longitudinally incoherent and consists of a broad spectrum of wavelengths. Its high brilliance makes it an excellent tool for materials research. Monochromators can be used to pick out individual wavelengths from the spectrum, but this reduces the radiant power by many orders of magnitude to values of a few watts only.
Size matters
But what if a storage ring were instead to deliver monochromatic, coherent light with outputs of several kilowatts, analogous to a high-power laser? Physicist Alexander Chao and his doctoral student Daniel Ratner found an answer to this challenge in 2010: if the electron bunches orbiting in a storage ring become shorter than the wavelength of the light they emit, the emitted radiation becomes coherent and therefore millions of times more powerful.
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Image: Jörg Feikes and PhD student Arnold Kruschinski in the control room of BESSY II and the MLS.
Credit: Ina Helms / HZB