The Joint Accelerator Conferences Website (JACoW) is an international collaboration that publishes the proceedings of accelerator conferences held around the world.
TY - CONF AU - Schneidmiller, E. AU - Yurkov, M.V. ED - Petit-Jean-Genaz, Christine ED - Kim, Dong Eon ED - Kim, Kyung Sook ED - Ko, In Soo ED - Schaa, Volker RW TI - Transverse Coherence and Fundamental Limitation on the Pointing Stability of X-ray FELs J2 - Proc. of IPAC2016, Busan, Korea, May 8-13, 2016 C1 - Busan, Korea T2 - International Particle Accelerator Conference T3 - 7 LA - english AB - The radiation from SASE FEL has always limited value of the degree of transverse coherence*. When transverse size of the electron beam significantly exceeds diffraction limit, the mode competition effect does not provide the selection of the ground mode, and spatial coherence degrades due to contribution of the higher azimuthal modes. An important consequence of this effect are fluctuations of the spot size and pointing stability of the photon beam**. These fluctuations are fundamental and originate from the shot noise in the electron beam. The effect of pointing instability becomes more pronouncing for shorter wavelengths. We analyze in detail the case of optimized SASE FEL* and derive universal dependencies applicable to all operating and planned x-ray FELs. We show that the hard x-ray FELs driven by low energy beams may exhibit poor spatial coherence and bad pointing stability. PB - JACoW CP - Geneva, Switzerland SP - 735 EP - 737 KW - FEL KW - radiation KW - electron KW - photon KW - emittance DA - 2016/06 PY - 2016 SN - 978-3-95450-147-2 DO - 10.18429/JACoW-IPAC2016-MOPOW012 UR - http://jacow.org/ipac2016/papers/mopow012.pdf ER -