Experimental study of staging method for two-stage pulse tube refrigerators for liquid 4He temperatures

✍ Scribed by C. Wang; G. Thummes; C. Heiden

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 846 KB
• Volume: 37
• Category: Article
• ISSN: 0011-2275
• DOI: 10.1016/s0011-2275(97)00142-2

✦ Synopsis

The first two-stage pulse tube refrigerator, providing a lowest temperature of 2.23 K and a cooling power of 370 mW at 4.2 K, employed a parallel arrangement of the two pulse tubes with phase shifters located at room temperature'. With the aim of increasing the COP at liquid 4He temperatures, three modified staging methods were tested in this paper. All refrigerator versions operate with the same two regenerators as already used in the first two-stage setup' and also the same 6 kW He-compressor combined with a redesigned G-M rotary valve. The best performance is achieved with a parallel arrangement two-stage refrigerator by introducing proper negative DC flow and impedance tubes. So far the highest cooling power achieved on the second stage at 4.2 K was 0.5 W. With a heat load of 20 W at 67 K on the first stage, the second stage can provide a cooling power of 0.42 W at 4.2 K. Details of the design of the different refrigerators and a comparison of their performance are presented.