Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Road to AC voltage standard leads to important junction

24.07.2006
After 10 years of research, the National Institute of Standards and Technology (NIST) has unveiled the world's first precision instrument for directly measuring alternating current (AC) voltages. The instrument is being tested for use in NIST's low-voltage calibration service, where it is expected to increase significantly the measurement precision of industrial voltmeters, spectrum analyzers, amplifiers and filters.

Described July 14 at the Conference on Precision Electromagnetic Measurements in Turin, Italy,* the patented instrument** is based on the same "Josephson junction" technology used in NIST's widely used direct current (DC) voltage standards, offering high precision based on quantum physics. A Josephson junction consists of two superconducting pieces of metal separated by a thin insulator or normal metal. When a fixed DC voltage is applied across it, a junction responds by generating an AC current that oscillates like a wave at a frequency exactly proportional to the applied voltage.

The new instrument uses arrays of junctions to generate AC pulses in precisely measured voltage units over a range of audio frequencies. Arbitrary waveforms can be generated at different voltage levels for different applications. The new standard would establish an entirely new method for AC voltage metrology. Until now, AC voltage calibrations have been performed indirectly, by measuring the heat delivered by an instrument to a resistor, and comparing that measurement to the heat delivered by a known DC voltage. At low voltages (such as 2 millivolts), the new AC Josephson junction voltage standard should improve measurement accuracy as much as 1,000-fold.

The concept for the new device was co-invented by researchers at NIST and Northrop-Grumman in the mid-1990s.*** A number of innovations since then have led to the first practical system. For instance, to increase the output voltage, NIST developed "nano-stacked" arrays of Josephson junctions, in which the spacing between junctions is reduced to less than 100 nanometers by stacking the junctions on top of each other. Using this technique NIST can make programmable voltage standard integrated circuits with over 130,000 junctions on a single chip. The new AC instrument currently has a maximum output of 100 millivolts; NIST researchers hope eventually to increase that level to 1 volt.

Laura Ost | EurekAlert!
Further information:
http://www.nist.gov

More articles from Power and Electrical Engineering:

nachricht A big nano boost for solar cells
18.01.2017 | Kyoto University and Osaka Gas effort doubles current efficiencies

nachricht Multiregional brain on a chip
16.01.2017 | Harvard John A. Paulson School of Engineering and Applied Sciences

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

A big nano boost for solar cells

18.01.2017 | Power and Electrical Engineering

Glass's off-kilter harmonies

18.01.2017 | Materials Sciences

Toward a 'smart' patch that automatically delivers insulin when needed

18.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>