arXiv subjects
Publications and source records attributed to Paul J. Channell.
We present a new scheme for establishing longitudinal coherence in the output of X-ray FELs. It uses a sequence of undulators and delay chicanes and the careful tailoring of the initial e-beam with time dependent focusing. Simulation of a simplified model of the FEL shows that the idea works well.
Transverse breathing mode oscillations in a particle beam can couple energy into longitudinal oscillations in a bunch of finite length and cause significant losses. We develop a model that illustrates this effect and explore the dependence on mismatch size, space-charge tune depression, longitudinal focusing strength, bunch length, and RF bucket length.
We formulate the theory of the two-stream instability (e-cloud instability) with electrons trapped in quadrupole magnets. We show that a linear instability theory can be sensibly formulated and analyzed. The growth rates are considerably smaller than the linear growth rates for the two-stream instability in drift spaces and are close to those actually observed.