Single-stage 4-valve and active buffer pulse tube refrigerators

A single-stage pulse tube refrigerator driven by a 7 kW scroll compressor i s equipped with a set of solenoid valves Such that two different operationa l modes can be realised, namely a 4-valve configuration and an active buffe r configuration. Typical refrigeration loads of 100 W at 57 K are achieved for both modes. In the 4-valve configuration, no-load temperatures down to 24.6 K are reached with the optimal valve settings for 57 K load measuremen ts. In this paper both systems are compared with respect to various operati onal parameters. (C) 2001 Elsevier Science Ltd. All rights reserved.