Jackson and Tull
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Creare

In August 2004, Jackson and Tull was tasked to design and build a protoflight Cryocooler Electronics (CCE) box for the Alaska Cryocooler System (ACS) under the Raytheon Contract. The CCE effort includes the design of the CCE box to drive a two-stage Reverse Turbo-Brayton (RTB) Cryocooler being designed and developed by Creare. J&T will deliver two sets of protoflight electronics to be used to test the engineering model (EM) and flight model (FM) cryocoolers.

The design of the Cryocooler Electronics and cryocooler is strongly based upon the NICMOS Cryocooler developed by J&T and Creare that is currently flying on the Hubble Space Telescope (HST). The J&T design electronics will consist of three rotating field inverters with duty cycle control voltage regulation. One inverter will supply power to the compressor motor. The other two will absorb power from the two turbo-alternators and regulate their speed. J&T will also design a digital system controller that will interface to the electronics control, and set the frequency and amplitude of the AC voltage waveforms for the three inverters to achieve commanded speeds and power levels, and temperature control. Control algorithms are expected to closely resemble those used in the NICMOS Electronics Support Module (ESM) for the NICMOS cryocooler. J&T will also design and build the signal conditioning electronics for telemetry used by the system controller, and the D/A and A/D converters that support the system controller.

The overall development effort is expected to take almost 2 years with final integration and test of the Cryocooler electronics box with the cryocooler being conducted at Creare located in New Hampshire. The CCE was originally scoped as a brassboard development effort and has growth to be protoflight development effort. The purpose for this change in scope was for J&T to develop a design that is as close to a flight design as possible to mitigate any potential risk with the flight delivery schedule.

To date, J&T has completed a preliminary design and just recently conducted an Advance Design Review that was held at the Raytheon facility in El Segundo, California. J&T will conduct the Preliminary Design Review in Spring 2005 and deliver the first of two CCE boxes for integration and test in September 2005.

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