Three-cell traveling wave superconducting test structure

TL;DR

This paper discusses the development and testing of a superconducting traveling wave accelerating structure, demonstrating promising results for higher gradients and longer cavities in particle accelerators.

Contribution

It presents the design, manufacturing, and successful testing of a single-cell feedback cavity, paving the way for a three-cell traveling wave superconducting cavity.

Findings

Single-cell cavity achieved high accelerating gradient

Feedback waveguide effectively recirculates RF power

Design of a three-cell cavity is underway

Abstract

Use of a superconducting traveling wave accelerating (STWA) structure with a small phase advance per cell rather than a standing wave structure may provide a significant increase of the accelerating gradient in the ILC linac. For the same surface electric and magnetic fields the STWA achieves an accelerating gradient 1.2 larger than TESLA-like standing wave cavities. The STWA allows also longer acceleration cavities, reducing the number of gaps between them. However, the STWA structure requires a SC feedback waveguide to return the few hundreds of MW of circulating RF power from the structure output to the structure input. A test single-cell cavity with feedback was designed, manufactured and successfully tested demonstrating the possibility of a proper processing to achieve a high accelerating gradient. These results open way to take the next step of the TW SC cavity development: to build and test a traveling-wave three-cell cavity with a feedback waveguide. The latest results of the single-cell cavity tests are discussed as well as the design of the test 3-cell TW cavity.