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 ( & gt;200ns) that currently are used in many designs. We propose a collider based on a short rf pulse (~22ns flat top), high gradient (~267MV/m loaded gradient), high frequency (26GHz) dielectric Two Beam Accelerator (TBA) scheme. This scheme is a modular design and its unique locally repetitive drive beam structure allows a flexible configuration to meet different needs. The preliminary study shows an efficient (~7% overall) short pulse collider may be achievable. As the first step, we will develop a 26GHz broadband Dielectric Loaded Accelerating (DLA) structure. Together with the existing 26GHz dielectric wakefield power extractor, we can test the first dielectric short pulse TBA prototype module in the project. Under Phase I of the project, we have finished conceptual design of a 26GHz short pulse TeV collider, which serves as the physics ground of the project--- the development of a 26 GHz dielectric-based TBA prototype. We have developed an alumina based DLA structure in order to restrict the group velocity of the accelerating mode to around 10% of the speed of light. We have finished the design of a new double-sided 26 GHz broadband coupler for the 26 GHz broadband dielectric accelerator. Two 26GHz broad band couplers are under fabrication. We will continue finish the complete 26 GHz dielectric-based broad band accelerating structure and test it at Argonne Wakefield Accelerator facility using the power from our previously developed wakefield power extractor. The complete two beam accelerator experiment is planned as well. Commercial Applications and Other Benefits: The proposed short rf pulse TBA can explore a new technique to achieve a significantly high gradient ( & gt;200 MV/m) and high power ( & gt;500 MW) machine which may proceed toward the design of a future collider. All engineering issues and their solutions in the process of this project will provide the basis of a practical dielectric based accelerator or power extractor in a practical dielectric-based two beam accelerator.