Low Temperature System for Thermal Conductivity Measurements

Abstract

Germanium and platinum resistance thermometers are used with two metal Dewars over the temperature range from 1.2 to 300°K. A variable conductance helium exchange gas switch is employed together with automatic heating to maintain any desired temperature within this range. Two coupled potentiometric dc measuring circuits are used—one to measure and control the sample temperature, and the other to measure the temperature gradient. The performance of the system is discussed.