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This paper describes a theoretical investigation of the ability of the rectifying interface to precisely control the temperature of a distributed load under dynamically changing conditions. The precise temperature regulation is enabled using temperature feedback control of a throttle valve placed in the loop. Flow modulation using the throttle valve is governed by a Proportional-Integral (PI) controller with gains that are selected to meet design temperature control criteria; specifically, a maximum temperature fluctuation and settling time. A linear thermal model based on experimental data is used to develop the control algorithm. The model demonstrates the ability to regulate the distributed load temperature under rapid load changes.

This paper describes progress towards the development of a large-capacity, singlestage, Stirling-type, pulse-tube refrigerator (PTR) for high temperature superconducting power applications. Specifically, the design and fabrication of an experimental PTR is described followed by a series of design modifications which have focused on optimization of the flow transition components the hot and cold ends of the pulse-tube. Computational fluid dynamic models are described and have been used to guide the design modifications. The impact of each modification on cooler performance is discussed. The cooler is instrumented with piston displacement sensors, high-frequency pressure sensors, and thermocouples along the regenerator wall, within the cold heat exchanger gas volume, and along the pulse-tube wall. These sensors provide some characterization of the flow distribution in the regenerator and pulse-tube.

This paper describes the design and preliminary experimental results for a large capacity (300W at 65 K) single-stage, Stirling-type pulse-tube. The regenerator, the critical component in the pulse-tube, was optimized via a parametric study accomplished using the REGENv3.2 program. The pulse tube system was subsequently designed using a 1st order model that calculates the pressure-flow characteristics of the system coupled with 2nd order models of the various internal loss mechanisms. An experimental pulse-tube system was fabricated based on this design; the pulse-tube apparatus allows simultaneous, high frequency measurement of instantaneous compressor piston position as well the instantaneous pressures at various locations in the system. In addition, the average temperatures along the regenerator, within the cold heat exchanger gas volume, on the cold heat exchanger surface, and along the pulse-tube are measured. This comprehensive set of measurements will allow a thorough evaluation and verification of the design model over a wide range of operating conditions including compressor stroke, frequency, charge pressure, and load temperature. This paper presents some preliminary experimental progress and compares the measured pressure-flow behavior with the design model predictions.