U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Search Publications by: Michael Lewis (Assoc)

Search Title, Abstract, Conference, Citation, Keyword or Author
Displaying 26 - 44 of 44

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

Inertance Tube Optimization for Pulse Tube Refrigerators

April 27, 2006
Author(s)
Ray Radebaugh, Michael A. Lewis, Ercang Lou, John M. Pfotenhauer, G. F. Nellis, L. F. Schunk
The efficiency of regenerative refrigerators is generally maximized when the pressure and flow are in phase near the midpoint of the regenerator. Such a phase relationship minimizes the amplitude of the mass flow for a given acoustic power flow through the

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

Measurement of Heat Conduction Through Bonded Regenerator Matrix Materials

December 1, 2003
Author(s)
Michael A. Lewis, Ray Radebaugh
Regenerative heat exchangers have had a significant influence on the development of small refrigerators for cryogenic applications. The optimized design of these regenerators takes into account the axial thermal conduction of the matrix. Until recently

Measurement of Heat Conduction through Metal Spheres

January 1, 2002
Author(s)
Michael A. Lewis, Ray Radebaugh
This paper describes the results of the measurements of heat conduction through a bed of packed metal spheres. Spheres were packed in a fiberglass-epoxy cylinder, 24.4 mm in diameter and 55 mm in length. The cold end of the packed bed was cooled by a

Effect of Regenerator Geometry on Pulse Tube Refrigerator Performance

June 1, 1998
Author(s)
Michael A. Lewis, T Kuriyama, J Xiao, Ray Radebaugh
This paper gives results of the cooling performance of a double-inlet pulse tube refrigerator using various redenerators. The same pulse tube was used for all the experiments and measured 4.76 mm in diameter and 46.2 m in length. A commercial linear

Measurement of Heat Conduction Through Stacked Screens

July 1, 1997
Author(s)
T Kuriyama, F Kuriyama, Michael A. Lewis, Ray Radebaugh
This paper describes the experimental apparatus for the measurement of heat conduction through stacked screens as well as some experimental results taken with the apparatus. Screens are stacked in a fiberglass-epoxy cylinder, which is 24.4 mm in diameter