Continuously Variable Inertance Tubes for Pulse Tube Refrigerators
Pfotenhaue, J. M.
MetadataShow full item record
The efficiency and cooling power of pulse tube refrigerators are highly dependent on the phase angle between the mass flow and pressure waves used to produce cooling. Inertance tubes are commonly used to set the phase angle for optimal efficiency. However, due to variations in fabrication or assembly, it is frequently unclear whether installed inertance tubes, with their fixed dimensions, produce the desired phase shift. A variable inertance tube allowing continuous adjustments to its geometry during operation has been constructed and mounted on a pulse tube, along with instrumentation to measure the pressure and mass flow oscillations and their relative phase at the interface between the inertance tube and pulse tube. A LabVIEW™-based lock-in amplifier enables real-time observation of the phase information. The variations in phase realized by changing the respective length and effective diameter of an inertance tube between 1.27 m to 1.55 m, and 6.52 mm to 6.61 mm, respectively, are compared to published models.