A multichannel electrometer voltmeter has been developed that employs a mechanical resonator with voltage-sensing capacitance-probe electrodes that enable high-impedance, high-voltage, radiation-hardened measurement of an Internal Electrostatic Discharge Monitor (IESDM) sensor. The IESDM is new sensor technology targeted for integration into a Space Environmental Monitor (SEM) subsystem used for the characterization and monitoring of deep dielectric charging on spacecraft.
The resonator solution relies on a non-contact, voltage-sensing, sinusoidalvarying capacitor to achieve input impedances as high as 10 petaohms as determined by the resonator materials, geometries, cleanliness, and construction. The resonator is designed with one dominant mechanical degree of freedom, so it resonates as a simple harmonic oscillator and because of the linearity of the variable sense capacitor to displacement, generates a pure sinusoidal current signal for a fixed input voltage under measurement. This enables the use of an idealized phase-lock sensing scheme for optimal signal detection in the presence of noise.
This work was done by Brent R. Blaes, Rembrandt T. Schaefer, and Robert J. Glaser of Caltech for NASA’s Jet Propulsion Laboratory. NPO-47335
This Brief includes a Technical Support Package (TSP).
Capacitance Probe Resonator for Multichannel Electrometer
(reference NPO-47335) is currently available for download from the TSP library.
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Overview
The document is a Technical Support Package from NASA's Jet Propulsion Laboratory (JPL) detailing the Capacitance Probe Resonator for a Multichannel Electrometer, identified as NPO-47335. This technology is part of NASA's efforts to develop advanced sensors for monitoring environmental conditions in deep space missions, particularly in extreme radiation and temperature environments.
The primary objective of the project was to create an integrated suite of environmental sensors that could provide real-time data critical for diagnosing spacecraft operational anomalies. This data would also serve as a valuable resource for optimizing future spacecraft designs. The project progressed through various phases, with specific goals set for fiscal years 2009 and 2010.
In FY09, the focus was on developing requirements and integration architecture for a Space Environment Monitoring (SEM) subsystem using commercial off-the-shelf hardware. By FY10, the project aimed to prototype a multichannel high-voltage electrometer designed to measure internal electrostatic discharges (IESDM) on spacecraft. This new sensor technology was intended to monitor deep dielectric charging, which is crucial for spacecraft safety and functionality.
The document highlights the successful design and construction of a prototype voltage-sensing capacitance-probe resonator for the IESDM electrometer. This resonator was built on a printed-wire board featuring an embedded coil and floating electrodes, which were suspended in a fixed magnetic field using flexure springs. The prototype underwent testing to validate its electromechanical model, and oscillator electronics were developed and tested in conjunction with the resonator.
Additionally, the document notes the design and construction of signal-chain electronics for the IESDM-measuring electrometer, which underwent open-loop tests with the capacitance-probe resonator. During these tests, an offset in measurements was observed due to parasitic capacitance couplings between the resonator's floating electrode and surrounding conductors at different potentials.
Overall, the document emphasizes the importance of this technology in enhancing the reliability and safety of spacecraft operating in challenging environments. It also acknowledges the support from the California Institute of Technology and the U.S. government in advancing this research. The findings and developments outlined in the document are intended to contribute to broader technological, scientific, and commercial applications beyond aerospace.
