RF thermal and new cold part design studies on TTF-III input coupler for Project-X

TL;DR

This study investigates thermal management and new cold part designs for the TTF-III RF input coupler in Project X, aiming to improve power handling and reduce temperature rise through simulations and design modifications.

Contribution

It introduces optimized copper coating thickness and a novel cold part design to enhance the performance of the TTF-III coupler for superconducting linacs.

Findings

Optimized copper coating reduces temperature rise.

New cold part design improves coupling and power handling.

Simulation results show decreased multipacting probability.

Abstract

RF power coupler is one of the key components in superconducting (SC) linac. It provides RF power to the SC cavity and interconnects different temperature layers (1.8K, 4.2K, 70K and 300K). TTF-III coupler is one of the most promising candidates for the High Energy (HE) linac of Project X, but it cannot meet the average power requirements because of the relatively high temperature rise on the warm inner conductor, some design modifications will be required. In this paper, we describe our simulation studies on the copper coating thickness on the warm inner conductor with RRR value of 10 and 100. Our purpose is to rebalance the dynamic and static loads, and finally lower the temperature rise along the warm inner conductor. In addition, to get stronger coupling, better power handling and less multipacting probability, one new cold part design was proposed using 60mm coaxial line; the corresponding multipacting simulation studies have also been investigated.