ABSTRACT
Viscosity molecular gauges operate on the principle of transferring molecular moment between gaseous molecules and mechanical elements that are in motion. The motion of the mechanical element is affected by a friction, drag, and forces of residual gases in vacuum. Viscosity gauges are also designed in the forms of oscillating fibers or very thin oscillating plates made of quartz. Some viscosity vacuum gauges have been developed into more sophisticated and high-precision devices with novel approaches and applications of contemporary electronics for the control of sensing elements and measurements of induced electronic signals. D. J. Pacey reported the oscillating Quartz crystals (QC) viscosity gauge in 1959. In QC viscosity gauges, electrical oscillation parameters—in particular the electrical impedance of oscillating crystals—change with the pressure variation in vacuum due to the friction of the oscillating crystals with molecules of vacuum background. Oscillations of QC bar and fork viscosity gauges have theoretically been studied using a string beads-model oscillator.
