A tuner for a superconducting traveling wave cavity prototype

Abstract

Use of a superconducting traveling wave accelerating (STWA) structure with small phase advance per cell for future high energy linear colliders may provide an accelerating gradient 1.2-1.4 times larger [1] than a standing wave structure. However, the STWA structure requires a feedback waveguide [1]. Recent tests of a 1.3 GHz model of a single-cell cavity with waveguide feedback demonstrated an accelerating gradient comparable to the gradient in a single-cell ILC-type cavity from the same manufacturer [2]. This opened the way for traveling wave cavity technology. A 3-cell traveling wave cavity was developed [3,4] and is being manufactured at AES, Inc [5].The tuner requirements for the traveling wave cavity are considered in this paper. The results of detailed studies of the mechanical and tuning properties of the superconducting resonator with a 3-cell traveling wave accelerating structure are also presented. The tuner design presented here was developed based on the results of these studies. A tuner test stand was developed and measured at room and liquid nitrogen temperatures under a 300 kg load to prove the tuner design feasibility. Test data are presented and discussed.

Flexible superconducting wiring for integration with low temperature detector and readout fabrication

“…If we take a reasonable value of 50 MPa for the yield stress in niobium, then we nd that niobium wiring begins to plastically deform for bend radiuses below 4 mm with a device layer thickness of 4 um. The breaking strain in niobium is larger than 0.4 [8], [9]. Imamura et al report superconductivity in niobium lms with both compressive and tensile stress up to 400 MPa [10].…”

Progress towards 3-cell superconducting traveling wave cavity cryogenic test

“…The cavity was optimized to withstand external pressure variations -stiffening ribs and rings were added to the mechanical design. Nevertheless, the cavity was still sensitive to the effects of the Lorentz force and a special tuner [5] was designed and built to compensate it. This paper presents some of the final stages towards cryogenic test of the threecell prototype: preliminary RF measurements and final manufacturing phase.…”