Research

Multijunction thermal converters are routinely used at many primary standards laboratories for ac voltage measurements and calibrations. After nearly two decades of inactivity, the Primary Standards Laboratory at Sandia National Laboratories has reestablished the process of fabricating silicon based multijunction thermal converters. Initial results indicate the devices perform similarly to devices fabricated circa 2001 with ac-dc differences of less than 2 mu mathrm{V}/mathrm{V} over the frequency range of 20 Hz to 20 kHz. From 20 kHz to 1 MHz, the ac-dc difference was higher, but remained below 200 mu mathrm{V}/mathrm{V}. In addition to presenting these results, new design considerations, such as high-resistivity substrates for high-frequency applications, are discussed.

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TYPE Conference Poster YEAR 2020

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Acoustic Chamber Characterization

O'Brien, Edward O.; Kypta, Timothy K.; Stanford, Joshua S.; Tran, Hy D.

The basis of this project was to characterize the various uncertainty contributors of an acoustic chamber. The acoustic chamber will be used to calibrate and characterize infrasound sensors used in the field in the frequency range of 0.001 Hz to 4 Hz. The components characterized include the internal volume of the chamber, the piston area of the speaker creating the dynamic sound wave, the environmental stabilization of the chamber and the chamber's leak rate. Also, the resonant frequency of the chamber was evaluated and found to be far outside the frequency band of interest. ACKNOWLEDGEMENTS The authors would like to acknowledge Randy Rembold and John Merchant for supporting and funding this project through the Defense Threat Reduction Agency (DTRA). We would also like to thank Henry Lorenzo and Monico Lucero of Manufacturing Liaison working along with Robert Jones and Tony Bryce of Mechanical Calibration for performing the dimensional measurements of the Acoustic Chamber. We would like to thank Curt Mowry and Adam Pimentel of Organization 01852 for measuring the density of a sample of the fiber-reinforced material of the grate. We would also like to thank the two main reviewers of this document Raegan Johnson and Dalai la Mora whose comments/suggestions helped improve and clarify this report.

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TYPE SAND Report YEAR 2018

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