High Power Rf Testing Of A 3-Cell Superconducting Traveling Wave Accelerating Structure

Superconducting rf technology has been recommended recently as the basis for the International Linear Collider, (ILC) accelerating structures. The principal goal of this proposal is development of a new experimental device - the Superconducting Traveling Wave Accelerator (STWA), a technology that may prove of crucial importance to the ILC. The present state of the art in superconducting structures has obtained a gradient of ~30 MV/m; the STWA technology in this proposal will further increase the gradient by a factor of up to ~1.40. We plan to design, develop and demonstrate the multi-cell Superconducting Traveling Wave Accelerating Structure under the scope of this project. Traveling wave SC accelerating structure need arises from demand for a high accelerating gradient. Proposed STWA structure operates at the same surface magnetic and electrical field magnitudes as the TESLA cavity surface to avoid undesirable superconductivity break down. The main goal of this new project is a 3-cell SC traveling wave cavity development and its experimental demonstration and testing. The mulitcell cavity with feedback will allow traveling wave excitation in the resonance ring and corresponding tuning studies that are of great importance for the SC traveling wave projects success. The tuning aspects of traveling wave regime stability and backward wave reduction at high power have been considered as a key issue for the SC traveling wave structure concepts. In Phase I of this project, the results of the optimization of a multi-cell L-band SC traveling wave cavity will be revisited along with the tuning issue analysis. Cavity shape, magnetic and electrical surface field ratios, inter-cell coupling coefficient, accelerating field flatness, and coupling section design will be reviewed. Special attention will be paid to feedback loop operations with the two coupler feed system. Based on these studies the requirements for the conceptual design of the traveling wave structure will be formulated. Commercialization Applications and Other Benefits: The main goal of the project is a development of the superconducting accelerating structure with the increased gradient for the linear collider. This structure will allow the total length of the linear collider to be reduced by 20-40% with a corresponding reduction in construction costs. The proposed structure is an inexpensive solution that permits the use of currently available accelerator components.