Experiment performance study of a single-stage coaxial pulse tube cryocooler pre-cooled by liquid nitrogen operating at 56 Hz: Achieving 0.5 [email protected] K cooling capacity

Abstract

The increasing demand for lightweight, high efficiency cooling systems in space cryogenic detection necessitates advancements in pulse tube cryocooler (PTC) design. Traditional two-stage PTCs precool the second-stage hot end to 80 K using the first stage, but the second-stage compressor operates at ambient temperature, inducing significant thermal losses in the transition regenerator due to temperature gradients. This inefficiency, coupled with low operating frequencies and high mass/volume limitations, impedes performance. This study proposes a new single-stage high frequency PTC system to replace traditional second-stage units, addressing compactness and efficiency challenges. The system employs liquid nitrogen precooling (total mass: 2.6 kg) and integrates an inertance tube-gas reservoir phase shifter with a stainless steel screen regenerator. A multi-physics coupling model optimizes phase modulation, enabling direct cooling in the 80 K range. At 1 MPa and 56 Hz with 10 W input power, the system achieves a no-load temperature of 15.8 K after precooling. Operational testing demonstrates 0.5 W effective cooling capacity at 25.5 K and a specific mass cooling power of 192 mW/kg. Frequency optimization reveals enhanced performance near 60 Hz, achieving a record low no-load temperature of 13.5 K at 62 Hz and effective cooling within the 20 K range. Further integration with a micro compressor (300 g, 30 W) is proposed, leveraging first-stage PTC precooling to minimize system volume and mass. This design advances high frequency PTC technology for space applications, offering superior cooling density and operational flexibility compared to traditional architectures.