Beam Physics Seminar
The cancellation effect has been an important and long-standing
controversial issue in the study of coherent synchrotron radiation (CSR)
induced electron bunch dynamics in bends.
In this talk, in order to illustrate the physical picture of the
cancellation effect, equations of motion are derived from the canonical
formulation of the dynamics for an ultrarelativistic electron bunch under collective interaction on a curved trajectory.
It is shown that two seemingly unrelated physical quantities for a bunch
in a bend, i.e., the kinetic energy change induced dispersion effect due
to the potential energy change, and the radial component of the collective radiative force, are actually strongly correlated. Using retarded potentials, we show that the logarithmic singularities in these two dynamical functions (resulted from the local interaction contributions) are actually cancelled, thus the local interactions influence the particle transverse optics only via the second or higher order terms.
The application of the cancellation effect in the CSR studies and
measurements is also highlighted.
Related Papers: PDF
(Coffee before the seminar starting 9:30 AM)