The maximum electron energy achievable in conventional resonant linear accelerators

Abstract

It is shown that, in resonant high-energy electron linear accelerators, undulator radiation should be observed, which is emitted by off-axis beam particles interacting with the transverse field of nonsynchronous spatial harmonics of the fundamental axisymmetric mode of a periodic accelerating structure. The mean power emitted by an individual electron is proportional to the squared distance between the electron and the accelerator axis and to the squared electron energy. This circumstance may limit the maximum energy to which offaxis beam electrons can be accelerated.