Development of a Dielectric-Based Short RF Pulse Two Beam Accelerator Prototype Module

Ultra-high gradient and ultra-high power rf are preferred for the future high energy collider design, but, due to the rf breakdowns, they are hardly to implement under the rf pulse length (>200ns) that currently are used in many designs. We plan to investigate a dielectric-based two-beam accelerator scheme using the short rf pulse (~20ns flat top) which may sustain a high gradient (>200 MV/m) in the accelerator with the generation of a fast rise time (500 MW), short rf pulse in the wakefield power extractor. In Phase I of this project, a new double-sided 26 GHz broadband coupler, which is to maintain the fidelity of a fast rise, short period rf pulse when feeding to the accelerating structure will be designed and fabricated for the 26 GHz Dielectric-Loaded Accelerating (DLA) structure. An alumina (dielectric constant of 9.7) based DLA structure in order to restrict the group velocity of the accelerating mode to around 10% of the speed of light (the dielectric constant plays the most important role in varying the group velocity of a DLA structure) will be made. Commercial Applications and benefits and Other Benefits: The short rf pulse Two-Beam-Accelerator presented here can explore a new technique to achieve a significantly high gradient (>200 MV/m) and high power (>500 MW) machine which may proceed toward the design of a future collider