Production of coherent soft X-rays in storage ring

With linac-based light sources, the electron beam has a high peak current and small energy spread, and this can be used to drive a seeded single pass free electron laser. On the other hand, the beams in a storage ring usually have a relatively low current and large energy spread. To generate ultrashort coherent radiation, the coherent harmonic generation (CHG) technique is a promising candidate. Dr. D. Xiang (SLAC National Accelerator Laboratory, USA) and Dr. W. Wan (Lawrence Berkeley National Laboratory, USA) have recently proposed a scheme to extend the harmonic number of the CHG technique by an order of magnitude using angular-modulated electron beams in the storage ring. The technique has the potential of generating femtosecond coherent soft X-ray radiation directly from an infrared seed laser. For more information, see the paper, "Generating Ultrashort Coherent Soft X-Ray Radiation in Storage Rings Using Angular-Modulated Electron Beams", D. Xiang et al., Phys. Rev. Lett. 104, 084803 (2010).