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Thermal Conductivity Measurements of Helium 4 Near the Lambda-Transition Using a Magnetostrictive Low Gravity SimulatorThere has been a recent increase in interest both experimentally and theoretically in the study of liquid helium very near the lambda-transition in the presence of a heat current. In traditional ground based experiments there are gravitationally induced pressure variations in any macroscopic helium sample that limit how closely the transition can be approached. We have taken advantage of the finite magnetic susceptibility of He 4 to build a magnetostrictive low gravity simulator. The simulator consists of a superconducting magnet with field profile shaped to counteract the force of gravity in a helium sample. When the magnet is operated with B x dB/dz = 21T(exp 2)/cm at the location of the cell, the gravitationally induced pressure variations will be canceled to within 1% over a volume of 0.5 cm in height and 0.5 cm in diameter. This technique for canceling the pressure variations in a long sample cell allows the lambda-transition to be studied much closer in reduced temperature and under a wider range of applied heat currents than is possible using other ground based techniques. Preliminary results using this low gravity simulator and the limitations of the magnetostrictive technique in comparison to doing space based experiments will be presented.
Document ID
20060038171
Acquisition Source
Jet Propulsion Laboratory
Document Type
Preprint (Draft being sent to journal)
External Source(s)
Authors
Larson, Melora
Israelsson, Ulf E.
Date Acquired
August 23, 2013
Publication Date
March 1, 1995
Distribution Limits
Public
Copyright
Other
Keywords
superconductive magnet heat current
helium magnetostrictive low gravity lambda-transition thermal conductivity

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