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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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Chapter
Advances in Helium Cryogenics
This review provides a survey of major advances that have occurred in recent years in the area of helium cryogenics. Helium-temperature cryogenics is the enabling technology for a substantial and growing numbe...
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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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Chapter
He II Heat Transport in Cylindrical Geometry
Temperature difference measurements are presented for two different sized radius cylindrical heaters, r = 1.6 and 4.8 mm, and at different radial positions in the fluid adjacent to the heater. Previous measure...
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Chapter
Measurement of the Pressure Distribution and Drag on a Sphere in Flowing Helium I and Helium II
We have designed and constructed an apparatus for measuring the pressure distribution around a sphere as a function of Reynolds number (mass flow rate) in both He I and He II. Liquid helium possesses kinematic...
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Chapter
Effect of Heat Transfer on Cooling of Current Leads
Current leads supply electrical current to high-field superconducting magnets, operating at low temperatures. The heat leak flowing down the current lead must be intercepted and extracted. In the present work,...
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Chapter
Liquid Level Control Using a Porous Plug in a Two-Phase He II System
This paper presents results of an experiment which decouples the liquid counterflow component from the evaporative component of heat transfer in the two-phase He II system. Two baths, partially filled with He ...
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Chapter
Bi-2212 Coils for 1 T Class Insert Coils
We present the construction and in-field testing of three insert coils using Bi-2212 conductor with pure silver and alloyed silver stabilizer. We use a stacked double pancake configuration, where double pancak...
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Chapter
Heat Transport in Saturated He II with Surface Heat Transfer in the Turbulent Counterflow Regime
Many large cryogenic systems provide refrigeration using pressurized He II that is cooled by a saturated bath heat exchanger. These heat exchangers consist of a closed-end tube or vessel filled with saturated ...
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Chapter
Finite Element Code for Quench and Stability Analysis of Superconducting Magnets Cooled by He II
The design of the protection system for the superconducting portion of the 45-T Hybrid Magnet System being constructed at the National High Magnetic Field Laboratory and the establishment of safe and reliable ...
