Pressure measurements with a precision of 0.001 ppm in magnetic fields at low temperatures

摘要

Pressure measurements made by an ac bridge technique with a precision of 0.001 ppm in magnetic fields at low temperatures using a Stratyndash;Adams type gauge are described. In order to improve the sensitivity and the longhyphen;term stability of the bridge system, coaxial cables without dielectric insulator were developed, with a small cable capacitance temperature coefficient of the impedance. This pressure measurement system has a sensitivity ofdP/Psim;5times;10minus;10and a longhyphen;term stability ofdP/Psim;2.4times;10minus;9over 18 h. This is especially useful for measurements such as electric and magnetic susceptibility measurements in magnetic fields at low temperatures requiring a high precision.