A magnetostrictive water pump using Terfenol-D has been designed and built, achieving a flow rate of 15mi/sec at 5 psi, using 41 watts. This is a higher flow rate and lower pressure than previous magnetostrictive pumps. The pump is 6" long and 3.6' in diameter. A model ofpump performance has been developed, including valve inertia which limits the drive frequency, and trapped air in the chamber, which can reduce the flow rate and make the pump noisy. Methods have been developed to eliminate trapped air. The pump uses a hydraulic stroke amplifier, which turned out much stiffer axially than it was designed to be. This has adversely affected pump performance, because of fmite Terfenol compliance and fmite housing compliance. With a stroke amplifier of optimal stiffness, and with better quality Terfenol, the pump should be able to achieve a flow rate of 30 mllsec at 5 psi, consuming 25 to 35 watts. Although the power is more than would be needed by a piezoelectric pump of the same performance, a Terfenol-D actuator offers important advantages, including low voltage and no known fatigue mechanism. Furthermore, much ofthe modeling would be relevant to a piezoelectric pump as well.
A novel radiation-hardened-by-design (RHBD) technique that utilizes charge sharing to mitigate single-event voltage transients is employed to harden bias circuits. Sensitive node active charge cancellation (SNACC) compensates for injected charge at critical nodes in analog and mixed-signal circuits by combining layout techniques to enhance charge sharing with additional current mirror circuitry. The SNACC technique is verified with a bootstrap current source using simulations in a 90-nm CMOS process. Reductions of approximately 66% in transient amplitude and 62% in transient duration are observed for 60-degree single-event strikes with an LET of 40 MeV*cm 2 /mg.The SNACC technique can be extended to protect multiple sensitive nodes (M-SNACC). M-SNACC is used to harden the bias circuit of a complementary folded cascode operational amplifier, providing a significant reduction in single-event vulnerability for a 8-bit digital-to-analog converter.
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