A thermal analysis and optimization of the APT 210 kW power coupler

Abstract

This paper presents the thermal analysis and heat load optimization of the continuous power 210 kW, 700 MHz RF power coupler (PC) for the Accelerator Production of Tritium (APT). The PC is a co-axial design with RF power transmitted in the annular region between two concentric cylinders. Thermally, the PC represents a link from room temperature to the superconducting niobium cavities operating at 2 K. The analysis includes all the major heat transfer mechanisms: conduction, RF joule heating in normal and superconducting materials, infrared radiation, and, forced and natural convection cooling of the inner and outer conductors. A performance comparison is given for one and two single point thermal intercepts, versus a counter-flow heat exchanger on the outer conductor. The benefits of r4educing the operating temperature of the center conductor are discussed. The variation in thermal performance of the inner and outer conductors for several operating modes is also presented