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Search Publications by: Ray Radebaugh (Assoc)

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Displaying 26 - 50 of 138

Cryocoolers for Aircraft Superconducting Generators and Motors

June 13, 2011
Author(s)
Ray Radebaugh
The proposal by NASA to use high temperature superconducting (HTS) generators and motors on future (2035) aircraft for turboelectric propulsion imposes difficult requirements for cryocoolers. Net refrigeration powers of about 5 kW to 10 kW at 50 K to 65 K

Experiments with Linear Compressors for Phase Shifting in Pulse Tube Cryocoolers

June 13, 2011
Author(s)
Michael A. Lewis, Peter E. Bradley, Ray Radebaugh
For the past year NIST has been investigating the use of mechanical phase shifters as warm expanders for pulse tube cryocoolers. Unlike inertance tubes, which have a limited phase shifting ability at low acoustic powers, mechanical phase shifters have the

Micro Cryogenic Coolers for IR Imaging

April 29, 2011
Author(s)
Ryan J. Lewis, Yunda Wang, Jill Cooper, Mu Hong Lin, Victor M. Bright, Yung-Cheng Lee, Peter E. Bradley, Ray Radebaugh, Marcia L. Huber
Joule-Thomson micro cryogenic coolers (MCCs) are a preferred approach for small and low power cryocoolers. With the same heat lift, MCC's power input can be only 1/10 of a thermoelectric cooler's input, and MCC's size can be only 1/10 of a Stirling cooler

Model for Transient Behavior of Pulse Tube Cryocooler

January 1, 2011
Author(s)
Gershon Grossman, Peter E. Bradley, Michael A. Lewis, Ray Radebaugh
This article describes an investigation of the transient behavior of a small (2.0 W at 85 K) Pulse Tube cryocooler operating at 120 Hz with an average pressure of 3.5 MPa, capable of relatively fast cool-down to about 60 K. In a series of experiments, the

Effect of Component Geometry on Flow Nonuniformities in a Large Pulse Tube Cryocooler

May 17, 2010
Author(s)
Michael A. Lewis, Ryan P. Taylor, Ray Radebaugh, Peter E. Bradley
A single-stage pulse tube cryocooler was designed to achieve 50 W of refrigeration power at 50 K when driven by a pressure oscillator that can produce up to 2.8 kW of acoustic power at 60 Hz. Initial experimental data produced no-load temperatures that

Mixed Refrigerants for a Glass Capillary Micro Cryogenic Cooler

April 24, 2010
Author(s)
Mu Hong Lin, Peter E. Bradley, Marcia L. Huber, Ryan J. Lewis, Ray Radebaugh, Yung-Cheng Lee
Optimized mixed refrigerants are applied in Joule-Thomson (JT) micro cryogenic coolers (MCC) to enhance efficiency. Mixed refrigerants deliver equivalent refrigeration power with much lower pressure ratio and flow rate compared to pure nitrogen refrigerant

Development of Miniature, High Frequency Pulse Tube Cryocoolers

April 5, 2010
Author(s)
Ray Radebaugh, Isaac Garaway, Alexander Veprik
Because acoustic power density is proportional to frequency, the size of pulse tube cryocoolers for a given refrigeration power can be reduced by operating them at higher frequencies. A frequency of about 60 Hz had been considered the maximum frequency

Diagnostics and Optimization of a Miniature High Frequency Pulse Tube Cryocooler

June 28, 2009
Author(s)
Isaac Garaway, Alexander Veprik, Ray Radebaugh
A miniature, high energy density, Pulse Tube cryocooler has been developed, tested, diagnosed and optimized to provide appropriate cooling for size-limited cryogenic applications demanding fast cool down. This cryocooler, originally designed using REGEN 3

Investigation of Flow Nonuniformities in a Large 50 K Pulse Tube Cryocooler

June 28, 2009
Author(s)
Michael A. Lewis, Ryan P. Taylor, Ray Radebaugh, Isaac Garaway, Peter E. Bradley
A single stage pulse tube cryocooler was optimized to provide 50 W of net refrigeration power at 50 K when driven by a pressure oscillator that can produce up to 2.8 kW of acoustic power at 60 Hz. The cryocooler was designed with the ability to provide

Optimization Calculations for a 30 HZ, 4 K Regenerator with Helium-3 Working Fluid

June 28, 2009
Author(s)
Ray Radebaugh, Yonghua Huang, Agnes A. O'Gallagher, John M. Gary
The NIST numerical software, REGEN3.3, which incorporates both He-4 and He-3 properties, was used to calculate the losses and second law efficiencies of 4 K regenerators operating at 30 Hz. Operating parameters, such as average pressure, pressure ratio

DESIGN, FABRICATION, AND ASSEMBLY OF A HOLLOW-CORE FIBER-BASED MICRO CRYOGENIC COOLER

June 21, 2009
Author(s)
James C. Booth, Mu Hong Lin, Peter E. Bradley, H.-j Wu, Ray Radebaugh, Y.C. Lee
One of the smallest Joule Thomson (J-T) micro cryogenic coolers (MCC) utilizing a hollow-core fiberbased heat exchanger (HX) is designed, fabricated, assembled and tested. Techniques that control mask material etching are developed to fabricate a multi

Cryocoolers: State of the art and recent developments

March 31, 2009
Author(s)
Ray Radebaugh
Cryocooler performance and reliability are continually improving. Consequently, they are more and more frequently implemented by physicists in their laboratory experiments or for commercial and space applications. The five types of cryocoolers most

Crycoolers and High-T c Devices

October 16, 2008
Author(s)
Ray Radebaugh
This chapter reviews various methods and their operating principles for producing cryogenic temperatures. The use of liquid cryogens for laboratory studies of superconducting electronic devices is a common practice. That technique is mentioned briefly but