24 Result(s)
within
S. W. Van Sciver
Characterization and Evaluation of Materials
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Article
Drag Measurement on an Oscillating Sphere in Helium II
Here we report measurement of the drag on a 3 mm oscillating sphere in superfluid 4He in the temperature range 1.6 K to 2.1 K. A Nb-Ti superconducting solenoid is used to suspend a niobium sphere; meanwhile a sim...
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Article
Separation of Micron-Scale Particles by Size Using Helium II
Here we report on a new technique we are develo** to classify micron scale particles, i.e., separate them by size, using superfluid 4He (He II). The technique is based on the unique property of He II, that is i...
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Article
Particle Image Velocimetry Studies of Counterflow Heat Transport in Superfluid Helium II
Heat is transported in helium II by a mechanism known as thermal counterflow where the liquid behaves as if it consists of two fluid components: the viscous normal fluid that carries the entropy and the invis...
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Article
Direct Measurements of Quantum Turbulence Induced by Second Sound Shock Pulses in Helium II
Direct measurements in a wide channel of He II at 1.7 K are presented of quantum turbulence induced by second sound shock (SSS) pulses. Such pulses are moving volume sources of power flux density, with the Vin...
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Article
The motion of micron-sized particles in He II counterflow as observed by the PIV technique
The motion of micro-spheres in He II thermal counterflow has been measured using the Particle Image Velocimetry (PIV) technique. Although the tracer particles are able to track the motion of the normal fluid c...
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Article
Tracer Particles for Application to PIV Studies of Liquid Helium
Material selection and methods for introduction of tracer particles into liquid helium are reviewed for application in particle image velocimetry experiments. The combination of low temperature environment and...
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Chapter
Optimal Integration of Binary Current Lead and Cryocooler
An optimal integration of a binary current lead and a two-stage cryocooler has been analytically sought to minimize the required refrigerator power. The binary current lead is a series combination of a normal ...
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Chapter
Thin-Film Thermometer and Heater Design for the Detection and Generation of Second Sound Shock Pulses
Using a known heater design, and a common type of pencil lead graphite in a novel thermometer design, second sound shock (SSS) pulses comparable to those of previous researchers were successfully transmitted a...
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Chapter
Numerical Study of Two-Phase Helium II Stratified Channel Flow
A key feature of the cryogenic system for the proposed TeV Superconducting Linear Accelerator (TESLA) is a He II two-phase flow line that provides cooling for the superconducting RF cavities. Understanding the...
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Chapter
A Particle Seeding Apparatus for Cryogenic Flow Visualization
A particle seeding apparatus to create neutrally buoyant solid particles in liquid helium (He I and He II) has been developed and successfully tested as part of a flow visualization experiment. The apparatus c...
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Chapter
Flow in Horizontal Two Phase He II /Vapor
Analytic and experimental studies of forced flow two phase He II and vapor in a horizontal channel are reported. A simple analytic model is presented that describes the steady state flow phenomena for both iso...
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Chapter and Conference Paper
Recent Developments in HTS Technology at the National High Magnetic Field Laboratory
The National High Magnetic Field Laboratory (NHMFL) has established a program that supports development of high temperature superconductors to generate the highest magnetic fields possible. A near term goal is...
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Article
Experimental evidence of homogeneous superfluid turbulence in large-pore porous media
Experimental results are presented for counterflow and isothermal coflow through large-pore porous materials, with porosities greater than 90% and permeabilities of order 10−11 m2. Counterflow velocities ranging ...
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Chapter and Conference Paper
Strain Dependence of Bi-2223 Tape Conductors for Application in High Field Magnets
We report preliminary results on the transport Jc of BiPb 2223/Ag tape conductors produced by the powder- in-tube method. Measurements include the temperature dependence of Jc between 4K and Tc on a variety of co...
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Article
Attenuation of second sound in bulk flowing He II
New measurements of second sound attenuation in bulk flowing He II are reported which extend to a region of higher Reynolds number. An expression for the attenuation explicitly containing the quantum vortex li...
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Chapter
Design and Performance of Forced-Flow HeII Heat Exchangers
HeII heat exchangers are used in systems requiring near absolute-zero temperatures. A unique characteristic of superfluid helium is its strong internal convection, which prevents the existence of pronounced te...
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Chapter
A Thin Film Flowmeter for use in Liquid Helium II
A novel flowmeter design has been investigated for the metering of liquid He II bulk flows in small channels. The flowmeter consists of a thin film heater with thin film temperature sensors located upstream an...
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Chapter
Pressure Drop of He II Flow Through a Porous Media
The behavior of liquid helium in porous materials continues to be of interest for the purpose of helium fluid management in a weightless environment. The present paper reports on measurements of He II pressure...
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Chapter
Characterization of a Centrifugal Pump in He II
As part of an effort to determine the feasibility of helium transfer in space a centrifugal pump was tested in He II at a variety of flow rates, pump speeds and fluid temperatures. The pump which has a straigh...
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Chapter
Application of a Square Function Heat Pulse to Forced Flow He II
The present is the third report on a series of experiments involving forced convection heat transfer in He II. A square function heat pulse is applied to the middle of a copper flow tube, 3 mm in diameter and ...
