Accession Number : AD0699162

Title :   A SPECIFIC HEAT AND FOURTH SOUND MEASUREMENT OF SIZE EFFECTS IN LIQUID HELIUM.

Descriptive Note : Technical rept.,

Corporate Author : CALIFORNIA UNIV LOS ANGELES DEPT OF PHYSICS

Personal Author(s) : Scott,Stephen Allan

Report Date : DEC 1969

Pagination or Media Count : 83

Abstract : An experimental and theoretical investigation of liquid helium confined to the small pores of highly compressed powders was made in order to investigate size effects in liquid helium. The specific heat measurements show that the bulk specific heat singularity is replaced by a flattened peak that is shifted towards lower temperatures with decreasing pore size. The theory of second order phase transitions was used to calculate the specific heat of liquid helium in finite systems. The superflow onset temperature and the super fluid fraction were determined from fourth sound (hydrodynamic pressure waves) measurements in the same powders in which specific heat measurements were made. The onset temperature and the temperature of the specific heat peak are equal within experimental error. (Author)

Descriptors :   (*POROUS MATERIALS, POWDERS), (*LIQUEFIED GASES, FILLING), (*HELIUM, SPECIFIC HEAT), (*SUPERFLUIDITY, HELIUM), POROSITY, PHASE STUDIES, ENTROPY, CRYOGENICS, HYDRODYNAMICS, MECHANICAL WAVES, MEASUREMENT, TRANSITION TEMPERATURE, COMPOSITE MATERIALS

Subject Categories : Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE