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Search Publications by: Ray Radebaugh (Assoc)

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Displaying 101 - 125 of 167

Heat Transfer Issues in Cryogenic Catheters

November 7, 2005
Author(s)
Ray Radebaugh
Catheters with diameters of 3 mm or smaller are capable of accessing many internal organs through arteries and veins. They provide the medical community with tools to operate on internal organs without the need to cut through the body to gain access. As a

Microscale Heat Transfer at Low Temperatures

September 26, 2005
Author(s)
Ray Radebaugh
This paper discusses the fundamentals and applications of heat transfer in small space and time domains at low temperatures. The modern trend toward miniaturization of devices requires a better understanding of heat transfer phenomena in small dimensions

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

Refrigeration for Superconductors

September 20, 2004
Author(s)
Ray Radebaugh
Temperatures in the range of 0.05 to 80 K are required for most applications of superconductors. Refrigeration powers range from fractions of a watt for many electronic applications to kilowatts for some large magnet and power applications. This paper

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

The Development and Application of Cryocoolers Since 1985

April 1, 2003
Author(s)
Ray Radebaugh
Many significant new developments in cryocoolers have occurred since about 1985 that have lead to grealy improved efficiencies, lifetimes, compactness, and low temperature limits. Many of the improvements have been spurred by the requirements of several

Refrigeration Methods for Superconductors

December 1, 2002
Author(s)
Ray Radebaugh
This chapter reviews various methods commonly used for achieving the cryogenic temperatures required of superconducting materials. The problems associated with cryogenic refrigerators (cryocoolers), such as poor reliability, low efficiency, electromagnetic

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