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Search Publications by: Peter Bradley (Fed)

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Displaying 26 - 50 of 50

Experimental investigation of Low-pressure refrigerant mixtures for Micro Cryogenic Coolers

February 4, 2013
Author(s)
Ryan J. Lewis, Yunda Wang, Peter E. Bradley, Marcia L. Huber, Ray Radebaugh, Y. C. Lee
Micro Cryogenic Coolers (MCCs) can achieve very small sizes and high efficiencies when operating with a refrigerant mixture, but micro-scale compressors have a limited pressure output. Four refrigerant mixtures were designed to operate between 0.4 MPa and

Development of a 4K Regenerator and Pulse Tube Test Facility

October 10, 2012
Author(s)
Michael A. Lewis, Peter E. Bradley, Ryan P. Taylor, Ray Radebaugh
Recent advances in superconducting electronic systems are requiring larger envelopes for cooling power, efficiency, and operational environments from commercial based cryogenic cooling systems. One such system targeted at meeting these requirements is the

Verification of the Back-EMF Method for Piston Velocity Measurements

July 10, 2012
Author(s)
Ray Radebaugh, Michael A. Lewis, Peter E. Bradley
Linear compressors are used to drive pulse tube or Stirling cryocoolers, and they can be used as expanders in place of inertance tubes when inertance tubes cannot provide sufficient phase shifts between flow and pressure. Commercial linear compressors

DEMONSTRATION OF AN INTEGRATED MICRO CRYOGENIC COOLER AND MINIATURE COMPRESSOR FOR COOLING TO 200 K

November 17, 2011
Author(s)
Ryan J. Lewis, Mu Hong Lin, Yunda Wang, Jill Cooper, Peter E. Bradley, Ray Radebaugh, Marcia L. Huber, Yung-Cheng Lee
Joule-Thompson (J-T) based micro cryogenic coolers (MCCs) are attractive because they can provide the cryogenic temperatures needed for small electronic devices while having a low cost and small volumetric footprint. A compressor is a major part of a

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

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

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

Pulse Tube Cryocooler for Rapid Cooldown of A Superconducting Magnet

June 9, 2008
Author(s)
Michael A. Lewis, Ryan P. Taylor, Peter E. Bradley, Isaac Garaway, Ray Radebaugh
A single-stage pulse tube cryocooler was designed to provide rapid cooldown of a high temperature superconducting (HTS) magnet that is part of a gyrotron required for the generation of a high-power mm-wave (95 GHz) beams. These beams are used in the

Impedance Measurements of Inertance Tubes at High Frequency and Pressure

July 16, 2007
Author(s)
Michael A. Lewis, Ryan P. Taylor, Peter E. Bradley, Ray Radebaugh, Gershon Grossman, Zhihua Gan
Previous comparisons between measured and calculated inertance tube impedance were made at frequencies below 70 Hz and average pressures below 3 MPa. In this paper, we present results on similar comparisons for frequencies up to 150 Hz and average

Cryogenic Technologies Group Website

June 11, 2007
Author(s)
Marilyn R. Yetzbacher, Peter E. Bradley
Revised website of Information pertaining to the Cryogenics Group. Provides general information, staffing, contact information, articles and publications relative to the subject of cryogenics and cryogenic coolers and their applications. Of a more

Characterization of Inertance Tubes Using Resonance Effects

June 14, 2006
Author(s)
Michael A. Lewis, Peter E. Bradley, Ray Radebaugh, Zhihua Gan
Inertance tubes can be characterized by their inertance, compliance, and resistance. All three of these impedance components are present during normal measurements of inertance tube impedance. As a result, in comparing experimental results with models it

Proposed Rapid Cooldown Technique for Pulse Tube Cryocoolers

June 14, 2006
Author(s)
Ray Radebaugh, Agnes O?Gallagher, Michael A. Lewis, Peter E. Bradley
Some cryocooler applications, such as those for military operations dealing with high temperature superconducting (HTS) magnets, motors, or generators, require faster cooldown times than what can normally be provided with a cryocooler designed to

Evaluation of Pressure Oscillator Losses

August 29, 2005
Author(s)
Peter E. Bradley, Michael A. Lewis, Ray Radebaugh
Efficiencies of regenerative cryocoolers are influenced by losses within the pressure oscillator (compressor). An evaluation of these losses is important when searching for ways to improve the overall cryocooler efficiency. Typically, compressor efficiency

Impedance Measurements of Inertance Tubes

August 29, 2005
Author(s)
Michael A. Lewis, Peter E. Bradley, Ray Radebaugh
The flow impedance of an inertance tube 5.74 mm inside diameter and 2.36 m long coupled to various reservoir volumes was measured and compared with that predicted by a model based on a transmission line analogy. Though data at other average pressures and

Measurements of phase shifts in an inertance tube

January 1, 2005
Author(s)
Michael A. Lewis, Peter E. Bradley, Ray Radebaugh, Ercang Lou
Phase shifts and mass flows were measured at the inlet of an inertance tube. and the results are compared with transmission line models. The mass flow rates at the entrance to the inertance tube are obtained using a hot-wire anemometer. The hot wire was