Publications [#191672] of Ying Wu

Papers Published
  1. S. Huang, J. Y. Li, Y. K. Wu, Experiments on Madey Theorem with Optical Klystron Free-Electron Laser, Proceedings of 2009 Particle Accelerator Conference (2009), pp. 1244-1246 .

    Abstract:
    The Madey the­o­rem is a valu­able re­search tool for study­ing Free-Elec­tron Lasers (FELs). The the­o­rem re­lates the shape of the on-ax­is spon­ta­neous ra­di­a­tion spec­trum of FEL wig­glers to the FEL gain. The the­o­rem pre­dicts that degra­da­tion of the spon­ta­neous spec­trum, for ex­am­ple as a re­sult of the in­crease of the elec­tron beam en­er­gy spread, pro­vides a di­rect mea­sure of the re­duc­tion of the FEL gain. Ex­ten­sive ex­per­i­ments have been per­formed to study the va­lid­i­ty of the Madey the­o­rem for a stor­age ring base op­ti­cal klystron FEL. The ex­per­i­men­tal data show that the las­ing wave­length of the FEL is very close to the max­i­mum slope of spon­ta­neous spec­tra as pre­dict­ed by the Madey the­o­rem with a rel­a­tive wave­length dis­crep­an­cy less than 0.2%. Fur­ther anal­y­sis is un­der­way to un­der­stand this wave­length dif­fer­ence. In ad­di­tion, we have per­formed di­rect mea­sure­ments of the start up gain of the FEL and com­pared it with the chang­ing slope of the spon­ta­neous spec­tra. The pre­lim­i­nary re­sults show a good agree­ment be­tween the mea­sured FEL gain and the pre­dic­tion by Madey the­o­rem.