Development of torodial magnetic thermometry to study new phenomena associated with the superfluid transition in liquid sup 4 He

Miscellaneous · Fri Jan 01 00:00:00 EST 1988

OSTI ID:6053856

Duncan, R V

A new type of paramagnetic susceptibility thermometry called toroidal magnetic thermometry (TMT) has been developed. These TMT thermometers have a thermal resolution of five nanoKelvin near the {sup 4}He superfluid transition temperature T{lambda} = 2.172K, making TMT roughly a factor of fifty times better in resolution than conventional germanium resistance thermometry which is commercially available. The dramatic improvement in thermal resolution provided by TMT has been used to observe new phenomena associated with the superfluid transition in pure liquid {sup 4}He. Such phenomena include a component of the thermal boundary (Kapitza) resistance R{sub K} which is singular at the superfluid transition temperature T{lambda}. In addition to the boundary effects described above, these TMT thermometers have been used to detect the depression of T{lambda} be a heat current Q flowing through the liquid helium. When these values of {Delta}T{lambda}(Q) were used to calculate the depression of the superfluid density {Delta}{rho}{sub s}(Q) the results agreed well with a prediction based on the theory of Ginzburg and Pitaevskii. The calibration of the TMT thermometers provide high-resolution measurements of the a.c. paramagnetic susceptibility of their magnetic salt: Copper ammonium bromide (CAB). These calibration parameters, together with power dissipation data near the CAB Curie temperature {Tc} = 1.79K, provide information on the magnetic critical behavior of this nearly ideal Heisenberg ferromagnet. Throughout the detailed description of the TMT design, aspects of the CAB magnetic critical phenomena are discussed.

• Research Organization: California Univ., Santa Barbara, CA (USA)
• OSTI ID: 6053856
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
47 OTHER INSTRUMENTATION
HELIUM 4
SUPERFLUIDITY
TRANSITION TEMPERATURE
THERMOMETERS
DESIGN
CALIBRATION
DENSITY
GINZBURG-PITAEVSKII THEORY
MAGNETIC SUSCEPTIBILITY
TEMPERATURE GRADIENTS
EVEN-EVEN NUCLEI
HELIUM ISOTOPES
ISOTOPES
LIGHT NUCLEI
MAGNETIC PROPERTIES
MEASURING INSTRUMENTS
NUCLEI
PHYSICAL PROPERTIES
STABLE ISOTOPES
THERMODYNAMIC PROPERTIES
640450* - Fluid Physics- Superfluidity
440500 - Thermal Instrumentation- (1990-)