ACTDP Cryocooler Concepts

As noted in the ACTDP 6K Cooler Development Program link, the ACTDP study phase led to four cryocooler designs capable of meeting the baseline requirements of 20 mW of cooling at 6 K, together with an additional 150 mW at 18 K. Three of these concepts ( the Ball, TRW and Lockheed concepts) were selected to proceed into the hardware demonstration phase (92). The four concepts are summarized below.

Ball ACTDP cooler concept

 

Ball Aerospace ACTDP Cryocooler Concept

As shown in the above figure, Ball Aerospace's ACTDP cryocooler concept utilized a multistage Stirling refrigerator to precool a J-T loop powered by a linear-motion Oxford-style compressor. The J-T loop provides remote cooling of the 6 K and 18 K loads and isolates the loads from compressor-generated vibration and EMI. No intermediate radiative precooling is required, and the compressor elements are easily separated by over 3 meters from the cryogenic loads. The multistage refrigerator is based on leveraging existing Ball flight-quality Stirling compressors, J-T cold-end technology, and drive electronics; these technologies are configured and adapted to meet the specific needs of the ACTDP mission requirements (88,95). The baseline concept has a projected total system mass of approximately 31 kg (including flight drive electronics) and has an estimated end-of-life input power of less than 200 watts into the drive electronics.

TRW ACTDP cooler concept

TRW ACTDP Cryocooler Concept

TRW's ACTDP cryocooler concept, illustrated above, utilizes a multistage pulse tube refrigerator to precool a J-T loop powered by a linear-motion Oxford-style compressor. The J-T loop provides remote cooling of the 6 K and 18 K loads and isolates the loads from any compressor-generated vibration and EMI. The multistage refrigerator is based on leveraging existing TRW flight-quality pulse tube compressors and drive electronics and developmental J-T cold-end technology; these are configured and adapted to meet the specific needs of the ACTDP mission requirements (87). The baseline concept shown in the accompanying illustration has a projected total system mass of approximately 27 kg (including flight drive electronics) and has an estimated end-of-life input power of <200 watts into the drive electronics.

Lockheed ACTDP cooler concept

Lockheed Martin ACTDP Cryocooler Concept

Lockheed Martin's ACTDP cryocooler concept (shown above) utilizes a multistage pulse tube refrigerator to directly cool the 6 K and 18 K loads. The single-unit multistage refrigerator leverages existing Lockheed flight-quality pulse-tube compressors, cold heads, and drive electronics, and laboratory pulse tube technology that has demonstrated direct cooling down to 4K; these are being configured and adapted to meet the specific needs of the ACTDP mission requirements (89). The baseline concept has a projected total system mass of approximately 25 kg (including flight drive electronics) and has an estimated end-of-life input power of less than 200 watts into the drive electronics.

Creare ACTDP cooler concept

Creare ACTDP Cryocooler Concept

Creare's ACTDP cryocooler concept utilizes a multistage turbo-Brayton refrigerator with optional precooling by a cryoradiator. The turbo-Brayton loop, which has remotely located turbo-expanders operating at 6 K and 18 K, generates minimal vibration and allows the 6 K and 18 K loads to be widely separated from the loop's room-temperature compressor and electronics. The multistage refrigerator is based on leveraging existing Creare flight-quality turbo-Brayton compressors, expanders, and drive electronics as well as new developmental hardware aimed at low temperature operation. These hardware elements are configured and adapted to meet the specific needs of the ACTDP mission requirements. The baseline concept, shown above, has a projected total system mass of less than 40 kg (including flight drive electronics) and has an estimated end-of-life input power well under 200 watts into the drive electronics when using the intermediate-temperature radiator.


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