High frequency pressure oscillator for microcryocoolers

Abstract

Microminiature pulse tube cryocoolers should operate at a frequency of an order higher than the conventional macro ones because the pulse tube cryocooler operating frequency scales inversely with the square of the pulse tube diameter. In this paper, the design and experiments of a high frequency pressure oscillator is presented with the aim to power a micropulse tube cryocooler operating between 300 and 80 K, delivering a cooling power of 10 mW. Piezoelectric actuators operate efficiently at high frequencies and have high power density making them good candidates as drivers for high frequency pressure oscillator. The pressure oscillator described in this work consists of a membrane driven by a piezoelectric actuator. A pressure ratio of about 1.11 was achieved with a filling pressure of 2.5 MPa and compression volume of about 22.6 mm 3 when operating the actuator with a peak-to-peak sinusoidal voltage of 100 V at a frequency of 1 kHz. The electrical power input was 2.73 W. The high pressure ratio and low electrical input power at high frequencies would herald development of microminiature cryocoolers.

Explosive Micro-Bubble Actuator

“…The actuator can be used produce sound and/or pressure waves. The performance of the cryocooler designed by Vanapalli et al [110] could be improved if smaller actuators are used. The bubble actuator is considerable smaller than the piezoelectric actuator used in their research and could therefore lead to an improvement of the performance.…”

Explosive micro-bubble actuator

“…The performance of the cryocooler designed by Vanapalli et al [110] could be improved if smaller actuators are used. The bubble actuator is considerable smaller than the piezoelectric actuator used in their research and could therefore lead to an improvement of the performance.…”