Two-Channel Dielectric Wakefield Accelerator

A rectangular dielelectric wake field electron accelerator would have attributes not found in other wake field accelerators. These attributes include: (1) continuous coupling between one channel, in which drive bunches travel, and a second channel, in which accelerated bunches travel, without the need for discrete transfer structures; (2) large step-up or transformer ratio in wake field amplitude in the acceleration channel, as compared to amplitude in the drive channel; and (3) rectangular geometry that affords relative ease in the precision fabrication of dielectric elements, along with improved beam stability. Together, these factors offer the possibility of achieving high acceleration gradients, as required for a future multi-TeV electron-positron collider. This project will build a rectangular, two-channel, dielectric wake field accelerator for a proof-of-principal experiment. First, a scaled-up, X-band bench-test model will be built to assess the effects of wall slots intended to damp higher-order modes. In Phase I, a five-zone rectangular dielectric wake field accelerator structure was analyzed to select tentative designs for an X-band bench-test prototype. Although the excitation of higher-order modes led to transverse wake forces similar to those in conventional accelerators, a number of strategies were identified to mitigate this effect. In Phase II, the X-band bench-test prototype structure will be built and tested to discover if design modifications are needed to account for the influence of wall slots. Then, an optimized. 80-GHz, two-channel dielectric wake field accelerator module will be built and experimentally tested. Analyses will be performed to identify a means to minimize the effects of transverse wakes. Commercial Applications and Other Benefits as described by the awardee: The two-beam, rectangular, dielectric wake field accelerator should enable the development of a multi-TeV collider for high-energy physics experiments. Because hundreds of modules ¿ each of which could have a commercial value of the order of $100,000 ¿ will be needed, the total market could to several tens of millions of dollars. In addition, the modular design would allow the accelerator to be built for a much lower final energy, as required for applications in medical radiology, industrial processing, and low-energy accelerator research and development.