Nearly copropagating sheared laser pulse FEL undulator for soft x-rays

• Published in: Journal of physics. D, Applied physics Vol. 46; no. 32; pp. 325501 - 1-11
• Main Authors: Lawler, J E, Bisognano, J, Bosch, R A, Chiang, T C, Green, M A, Jacobs, K, Miller, T, Wehlitz, R, Yavuz, D, York, R C
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 14.08.2013; Institute of Physics
• Subjects: Beams (radiation); Doppler effect; Electron beams; Exact sciences and technology; Free electron lasers; Free-electron lasers X-ray lasers X-ray beams; Gain; Lasers; Physics; Relativistic electron beams; Soft x-rays; Near infrared radiation; Shear; Electron beams; Hard x radiation; Soft X radiation; Laser pulse; Wide band; Laser radiation; Exitance; Titanium; Free electron; Doppler effect
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/46/32/325501

A conceptual design for a soft x-ray free-electron laser (FEL) using a short-pulsed, high energy near infrared laser undulator and a low-emittance modest-energy (∼170 MeV) electron beam is described. This low-cost design uses the laser undulator beam in a nearly copropagating fashion with respect to the electron beam, instead of the traditional 'head-on' fashion. The nearly copropagating geometry reduces the Doppler shift of scattered radiation to yield soft, rather than hard x-rays. To increase the FEL gain a sheared laser pulse from a Ti : sapphire or other broadband laser is used to extend the otherwise short interaction time of the nearly copropagating laser undulator beam with a relativistic electron beam.