Low Input Power 4 K Pulse Tube Cryocooler Driven by an Inverter Helium Compressor: Intrinsic Temperature Oscillations and Mechanical Vibrations

Abstract We report on the intrinsic mechanical vibrations and thermal oscillations of a small-scale two-stage pulse tube cryocooler operated by an inverter driven helium compressor. The combination offers a cooling power ranging from 35 to 156 mW at 4.0 K with an electric input power of 0.9 to 2.3 kW respectively. This system has been characterized with respect to mechanical and temperature stability. The acquired data from an accelerometer attached to the 2 nd stage of the cryocooler shows a longitudinal peak-to-peak displacement of a few tens of μ m. Additionally, temperature oscillations of a few hundred mK were found, with a maximum around 10.5 K. Based on this characterization, this article presents the reduction of these unwanted intrinsic effects by use of a compressor with variable operation modes.