Theory of wakefields in a dielectric-filled cavity

Abstract

An analytical solution of a wakefield from a charge moving on the axis of a dielectric-filled cylindrical cavity is derived. A solution to the wakefield in a waveguide with only a boundary at the cavity entrance is already known. To take into account a boundary at the cavity exit, we introduce an imaginary antibeam, with opposite charge, which is created at the same time when the beam passes the exit boundary and continues to move along with the original beam at the same velocity. Although the beam has been annihilated in the net effect, the original beam and the antibeam produce their own wakefields, respectively, because they were created at different times. These superimposed fields are then mirror reflected as usual by the conducting exit boundary and the wakefield can be obtained by properly mirror reflecting them whenever it reaches a boundary. We find a resonance condition to enhance wakefields with multiple bunches of charges, and show that the acceleration gradient increases under that condition.

Electron bunch length measurement with a wakefield radiation decelerator

“…To compare the analytical and the simulated DWR spectrum result, we delete the longitudinal field components in the edge and interference zones according to Refs. [26][27][28], then the simulated DWR spectrum can be…”

Terahertz Acceleration Technology Towards Compact Light Sources

“…In this study, we neglect F wf i because the relatively short propagation distances and bunch lengths make the effect of wakefields negligible. For acceleration studies involving long propagation distances, or multiple bunches of substantial charge, wakefields should be taken into consideration by implementing formulas derived in previous studies [354]. We also neglect the radiation reaction force since the employed scheme accelerates the electrons primarily via the z-directed component of the electric field, with minimal transverse wiggling.…”

Effect of Transition Radiation and Dispersion Spreading at Achievement of a Large Transformer Ratio of Driver-Bunch Energy Into Wakefield in a Dielectric Resonator Accelerator

“…Also the computer simulation of wakefield excitation in the cylindrical dielectric resonator by the train of three bunches has been performed. The contribution of dispersion spreading and transition radiation (see [20]), excited at the input and output boundaries of the resonator, into the wakefield is taken into account. It has been shown that the dependence R=2N, which follow from the theory for Cherenkov radiation is performed approximately.…”