The importance of producing accelerating gradients larger than those achievable with radiofrequency acceleration is well recognized. Large gradients will be necessary for the next generation electron-positron colliders and, in the more moderate energy range, for compact high brightness linacs suitable for applications as the injector for free-electron lasers. Among the alternative acceleration techniques of current interest are the laser-plasma, plasma wake-field and wake-field acceleration process. For those acceleration mechanisms involving plasmas, the periodicity of the structures is in general on the order of sub-millimeters so that accelerating gradients on the order of 1 GV/m is theoretically possible. Wake-field cavities are on the order of a few millimeters, thus will yield lower gradients on the order of 150 MeV/m. This gradient, if achieved empirically in particle acceleration, is sufficient for near term applications. Moreover, it probably is the most practical technique among those that were proposed recently from the point of view of fabrication and ease of phase matching in linac application. A program to investigate the feasibility of wake-field acceleration with an emphasis on the use of ellptical cavities is discussed here. A complete modal analysis was carried out which yields a full description of the wake-field acceleration mechanism. Experimental studies are in progress.
K W Chen, K W Chen,
S H Kim, S H Kim,
"Wake-Field Acceleration And Compact Accelerator Considerations", Proc. SPIE 0873, Microwave and Particle Beam Sources and Propagation, (9 May 1988); doi: 10.1117/12.965098; https://doi.org/10.1117/12.965098