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  • 1
    Electronic Resource
    Electronic Resource
    Damping of mechanical vibration by superconducting YBa2Cu3O7−x in a magnetic field (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 643-645 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: As the load capacity of magnetic bearings using high-Tc superconductors increases, the inherent damping decreases. Damping of externally generated vibration is an important unsolved problem. A proposal is made for an active damping system, based upon the strong temperature dependence of the magnetic flux dissipation in a high-Tc superconductor in the region of the phase transformation a few degrees below the transition temperature. The damping system would be distinct from the levitated system. The strong temperature dependence of the dissipation is demonstrated with a single crystal of yttrium barium copper oxide, but a melt-processed ceramic sample would behave in the same way. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114146
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  • 2
    Electronic Resource
    Electronic Resource
    Measurement of the thermomechanical coefficient in confined normal liquid3He (1995)
    Springer
    Journal of low temperature physics 101 (1995), S. 775-779 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The thermomechanical coefficient ΔP/ΔT has been measured for liquid3He from 2–20 mK. The temperature difference was established across3He in a porous plug with 90 nm pore diameter. The coefficient was ∼ 5 kPa K−1 and only weakly temperature dependent; in terms of the heat capacity per unit volume, the coefficient varies from ∼ 4C at 2 mK to ∼ C at 20 mK.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00753389
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  • 3
    Electronic Resource
    Electronic Resource
    Direct Measurement of the Thermal Expansion of Liquid 3He (1999)
    Springer
    Journal of low temperature physics 116 (1999), S. 433-441 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have made a direct measurement of the thermal expansion of liquid 3 He between 1 and 200 mK at saturated vapour pressure, by measuring the change in volume as a function of temperature with a coaxial capacitive level detector. Our results do not depend on calibrations against known liquids, nor require any other data as input. We find good agreement with other, less direct methods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021767727875
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  • 4
    Electronic Resource
    Electronic Resource
    Kapitza resistance—A universal curve (1974)
    Springer
    Journal of low temperature physics 17 (1974), S. 43-48 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It is shown that when all unquestionable data on Kapitza resistance are plotted as reduced thermal boundary resistivity versusTϑD, then a universal curve results. The curve shows that for smallTϑD they are close to the acoustic mismatch theory, and for largeTϑD they are close to the phonon radiation limit. The parameterTϑD extends over three orders of magnitude, which compares with the usual factor of two in most measurements. The universality has several implications: First, it shows that Kapitza resistance is to first approximation a bulk effect; next, the curve can be used to test theories of Kapitza resistance (an example is given); finally, the value for an unmeasured solid-liquid helium interface can be estimated with some reasonable confidence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00654542
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  • 5
    Electronic Resource
    Electronic Resource
    The thermomechanical effect in normal liquid3He (1995)
    Springer
    Journal of low temperature physics 101 (1995), S. 1013-1022 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A thermomechanical effect has been found in normal liquid3He. The effect appears only when the temperature gradient is established across liquid3He confined in small pores so that the3He quasiparticle scattering is boundary limited. This was achieved with a porous plug of packed 70 nm copper-oxide powder. The magnitude of ΔP/gDT varies from 4 C at 2 mK to ∼C at 20 mK, where P is pressure, T is temperature and C is the heat capacity per unit volume. The sign is positive, meaning that the3He “moves” from cold to hot. If viewed as an analogue of thermoelectricity, the magnitude of this thermomechanical effect is unsurprising. However, as shown in the following paper, it is an order of magnitude larger than a theoretical prediction for liquid3He.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00754521
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  • 6
    Electronic Resource
    Electronic Resource
    The anomalous heat capacity of cerium magnesium nitrate (1977)
    Springer
    Journal of low temperature physics 27 (1977), S. 25-35 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract It has been demonstrated in several laboratories that the heat capacity of cerium magnesium nitrate is anomalous above 20 mK. The origin of the anomaly is unknown. We have measured the heat capacity of three samples of cerium magnesium nitrate from 0.15 to 0.6 K. The samples were: (a) from a cloudy region of a large single crystal grown from nominally 95% starting material, (b) from an optically clear region of the same single crystal, and (c) from a single crystal grown from 99.9% starting material. Within the scatter of the data the three heat capacity determinations showed the same anomaly as observed elsewhere; after subtracting an appropriate lattice contribution, the heat capacity above 0.1 K is more than twice that expected for a set of interacting magnetic dipoles on a regular lattice. The “cloudy sample versus clear sample” results ruled out crystal growth problems as the source of the anomaly. Chemical analysis by neutron activation analysis, mass spectrographic analysis, and optical absorption spectroscopy all showed the presence of approximately 0.06% praseodymium to cerium ratio in the two single crystals. The heat capacity arising from the hyperfine splitting of the non-Kramers doublet ground state of that concentration of praseodymium ions in cerium magnesium nitrate accounts for the heat capacity anomaly in magnitude and temperature dependence. No serious consequences are expected regarding the use of cerium magnesium nitrate as a primary thermometric substance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00654635
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  • 7
    Electronic Resource
    Electronic Resource
    Surface area of powdered cerous magnesium nitrate (1970)
    Springer
    Journal of low temperature physics 2 (1970), S. 157-160 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The anomalously small thermal boundary resistance between liquid He3 and powdered cerous magnesium nitrate (CMN) crystals must be due either to an unexpectedly large surface area, to a porous surface layer, or to a new coupling mechanism between the thermal excitations on either side of the interface. Measurement of the surface area of powdered CMN by the BET adsorption method shows that the first two possibilities can be ruled out.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00628109
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  • 8
    Electronic Resource
    Electronic Resource
    Phonon reflection at a silicon-3He interface (1978)
    Springer
    Journal of low temperature physics 32 (1978), S. 469-479 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: The reflection of heat pulses at an interface between the (111) surface of silicon and liquid 3He has been measured for heat pulse temperatures from 1.4 to 9K. The measurements were made with the silicon-helium temperature equal to 0.4 or 1.8K. The detectors were cadmium or aluminum superconducting bolometers. Longitudinal and transverse phonons incident nearly perpendicularly on the surface had reflection coefficients of 1 and 0.8, respectively, independent of pulse temperature. Transverse phonons incident at a large angle and diffusely reflected had reflection coefficients dropping from 0.7 at 1.5K to 0.4 at 9K. The results are in broad agreement with previous measurements on solid-4He interfaces obtained from heat pulse and monochromatic phonon experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00117964
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  • 9
    Electronic Resource
    Electronic Resource
    The vibrating wire viscometer as a magnetic field-independent3He thermometer (1988)
    Springer
    Journal of low temperature physics 70 (1988), S. 393-411 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract An analysis of the semicircular loop, vibrating-wire3He viscometer has been made. Emphasis was placed upon the magnetic field dependence of the resonance frequency and frequency width (damping) in order to study the suitability of the device for a field-independent thermometer. The analysis was complemented by experiments with Ta, Nb-Ti, Cu, Ag, Au, and Cu-Ni wires. It was found that the various wires, whether superconducting or pure or impure normal metals, have advantages and disadvantages. The superconducting wires show a large field-dependent frequency shift due to induced magnetization and a field-dependent damping due to flux motion. Pure normal metals also show induced magnetization (eddy-current) frequency shift and damping, and impure metals and alloys give Joule heating. Nevertheless, it is shown that the device can be used in the range 1–10 mK and for fields from 20 mT to 1 T.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00682788
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  • 10
    Electronic Resource
    Electronic Resource
    Critical temperature and critical current of thin-film superfluid3He (1988)
    Springer
    Journal of low temperature physics 70 (1988), S. 547-568 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Superfluid3He film flow over the rim of a copper beaker has been measured. The flow rate was measured as a function of temperature and as a function of depth of3He below the rim or film thickness at the rim. The critical current, calculated from the flow rate, varied as (1 −T/T c p )3/2 as expected for pair-breaking;T c p is a film-thickness-dependent critical temperature. However, the magnitude of the current was an order of magnitude smaller than expected for pair-breaking, in agreement with other experiments that have demonstrated a lower dissipation mechanism in superfluid3He. The suppression of the critical temperatureT c p /T c b , whereT c b =0.93 mK is the bulk3He transition temperature, varied from 0.93 to 0.7 as the film thickness at the rim varied from 120 to 90 nm. These ratios are larger than expected from Ginzburg-Landau or microscopic theory of superfluid3He-B.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00682165
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