Wakefields in Dielectric-Loaded Rectangular Waveguide Accelerating Structures
AIP Conference Proceedings
Employing modal analysis, an accurate formulation to represent the electromagnetic wakefields generated by an electron charge bunch traveling along an off-center axis in a dielectric loaded rectangular waveguide accelerating structure is presented. The resulting xdipole and y-dipole modes are described in detail. Specific analytical results were obtained for the dispersion characteristics, the transverse force, and the longitudinal wakefields. CP647, Advanced Accelerator Concepts: Tenth
... epts: Tenth Workshop, edited by C. E. Clayton and P. Muggli © 2002 American Institute of Physics 0-7354-0102-0/02/$19.00 542 wake field should consist of monopole modes LSMi n plus LSEi n  and the dipole mode in x-direction, (which we denote as x-dipole) and the dipole mode in y-direction (y-dipole). Here, we neglect the other higher order modes because we assume that the bunch trajectory does not deviate far from the axis, and keeping terms to this order is sufficient to ensure the accuracy of the final results. We have verified this by comparing our analytical results with a numerical simulation using a commercial EM code. The organization of this paper is as follows. In section II, we obtain the analytical expressions for the EM field components of multipole modes through potential functions, and then we calculate R over Q [R/Q], a very important structure parameter, for each related mode. Because R/Q has a very simple relation to the loss factor ki of beam loading , we can obtain the longitudinal component of the wakefield amplitude excited by a charged particle traveling beam easily, rather than computation of the wakefield using the Panofsky-Wenzel theorem as  .