Transformer Ratio Enhancement Experiment for Next Generation Dielectric Wakefield Accelerators

70838B02-II Dielectric wakefield acceleration is presently being studied intensively as a promising technique to provide efficient and cost effective high gradient acceleration of electrons for next generation linear colliders. This project will develop an experimental scheme to enhance the efficiency of dielectric wakefield acceleration by up to a factor of 4, compared to conventional collinear wakefield accelerators. In particular, a ramped, multibunch Dielectric Wakefield Accelerator, for increasing the efficiency of energy transfer from, the accelerating structure to the accelerated electron beam will be designed, developed, and demonstrated. In Phase I, the ceramics to be used in the accelerating structure were manufactured, and the required mechanical tolerances of 3-10 ?m and uniformity of dielectric properties in the range of 0.35% were achieved. A 13.625 GHz accelerating structure (dielectric permittivity of 16 and loss-factor in the range of 1-1.2 x 10-4) was fabricated and tested, and a prototype laser beam splitter was installed to produce a ramped bunch train of 4 bunches. The laser multisplitter was refined to provide control of the intensities, and ramped bunch train parameters were simulated and optimized for the accelerating structure. Phase II will complete both the engineering design and beam testing of the 13.625 GHz dielectric loaded accelerating structure, and improve the laser multisplitter for fine-tuning and final adjusting. Two features will be demonstrated: (1) generation of the Ramped Bunch Train with the characteristics required for the maximal Transformer Ratio value, and (2) bunch train propagation through the accelerating structure with control of bunch break up (BBU) effects. Commercial Applications and Other Benefits as described by awardee: The enhanced efficiency for Wakefield acceleration could be applied to a variety of accelerators, not only those dedicated to high energy physics. In addition, the advanced ceramic material developed for the accelerating structure should find multiple applications for dielectric resonators and filters in the wireless communication market, and also may find application to radar and stealth technologies.