Author:
Li Jintao,Wang Na,Yue Sen,Tian Saike
Abstract
Abstract
Undulators with small gap have been widely used in various
light sources all over the world for the demand of high brilliance.
A large number of in-air undulators with small gap will be installed
in the storage ring of the High Energy Photon Source, and become one
of the important impedance contributors. Antechambers are adopted
for the bypass of the synchrotron radiations, as well as to reach
high vacuum in the beam pipe with small aperture. Due to the
asymmetric structure of the vacuum chamber, monopole wakefield in
the transverse planes will be excited by the beam passage. In
addition, photon absorbers will be installed in the vacuum chamber
of the in-air undulators to shield the downstream components, which
will introduce extra resonances in the transverse planes. In this
paper, a series of numerical simulations are performed to
investigate the impedance of the in-air undulator vacuum chamber.
The high order modes generated by the photon absorber and their
mitigations are also investigated.
Subject
Mathematical Physics,Instrumentation
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