Electron beam energy spread measurements using optical klystron radiation

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In accelerators, the electron beam longitudinal dynamics critically depend on the energy distribution of the beam. Noninvasive, highly accurate measurement of the energy spread of the electron beam in the storage ring remains a challenge. Conventional techniques are limited to measuring a relatively large energy spread using the energy spread induced broadening effect of radiation source size or radiation spectrum. In this work, we report a versatile method to accurately measure the electron beam relative energy spread from 10 -4 to 10-2 using the optical klystron radiation. A novel numerical method based on the Gauss-Hermite expansion has been developed to treat both spectral broadening and modulation on an equal footing. A large dynamic range of the measurement is realized by properly configuring the optical klystron. In addition, a model-based scheme has been developed for the first time to compensate the beam-emittance-induced inhomogeneous spectral broadening effect to improve the accuracy of the energy spread measurement. Using this technique, we have successfully measured the relative energy spread of the electron beam in the Duke storage ring from 6×10-4 to 6×10-3 with an overall uncertainty of less than 5%. The optical klystron is a powerful diagnostic for highly accurate energy spread measurement for storage rings and other advanced electron accelerators. © 2010 The American Physical Society.






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Jia, B, J Li, S Huang Scott, C Schmidler and YK Wu (2010). Electron beam energy spread measurements using optical klystron radiation. Physical Review Special Topics - Accelerators and Beams, 13(8). p. 80702. 10.1103/PhysRevSTAB.13.080702 Retrieved from https://hdl.handle.net/10161/4310.

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Ying Wu

Professor of Physics

Prof. Wu is interested in nonlinear dynamics of charged particle beams, coherent radiation sources, and the development of novel accelerators and light sources. One of his research focuses is to study the charged particle nonlinear dynamics using the modern techniques such as Lie Algebra, Differential Algebra, and Frequency Analysis. This direction of research will significantly further the understanding of the nonlinear phenomena in light source storage rings and collider rings, improve their performance, and provide guidance for developing next generation storage rings. The second area of research is to study and develop coherent radiation sources such as broad-band far infrared radiation from dipole magnets and coherent mm-wave radiation from a free-electron-laser (FEL). With this direction of research, he hopes to study the beam stability issues, in particular, the single bunch instabilities in the storage ring, develop diagnostics to monitor and improve the stability of the light source beams, and eventually develop novel means to overcome instabilities. These areas of research will provide foundations for developing a femto-second hard x-ray Compton back scattering radiation source driven by a mm-wave FEL - a next generation light source.

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