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Cryoelectronics and Their Use in the JWST Optical Telescope Element Control Electronics
Keywords: Cryoelectronics , Extreme Cold, Reliability
The James Webb Space Telescope (JWST) is a large (6.5 meter aperture), multi-segmented telescope consisting of 18 hexagonal primary mirror segments that is passively cooled to temperatures as low as 25 Kelvin. A set of cryogenic actuators, each consisting of a motor, resolver, two LVDTs, and two temperature sensors, are mounted to each mirror segment and are used to control the positioning and radius of curvature of the mirrors. A large number of actuators (132) are required to adjust the wavefront of the primary mirror, and each actuator requires many wires to carry power and instrumentation signals between the actuators and control electronics. In order to reduce the thermal heat leak from the warm control electronics to the passively cooled region of the telescope and to reduce the mass of electronic cables and the overall mass of the spacecraft, JWST uses a unique electronics architecture consisting of 22 cryogenic flight electronics boxes that are used to multiplex signals from the warm control electronics to one actuator at a time. In the design and development of these 22 cryogenic electronics boxes, Ball Aerospace has done extensive cryogenic characterization testing on a wide range of electronic part types including resistors, capacitors, diodes, digital ICs, analog switch ICs, and discrete MOSFET’s. These tests included characterization of device performance over the temperature range of 300K down to 10K as well as total-ionizing dose radiation testing while the parts’ temperature was maintained at 30K during irradiation. This presentation will provide an overview of the cryogenic temperature and radiation test results for active and passive components that have been tested by Ball Aerospace for use on JWST.
Mr. Sandor Demosthenes , Senior Engineer
Ball Aerospace & Technologies Corp.
Boulder, CO

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