Whenever two pieces of metal at different voltages are brought near each other, as when an appliance is plugged into a live socket, there is a chance there will be an arc between them.
Even in a vacuum, voltages can literally tear metal apart. Current research is using molecular dynamics to show what happens at the atomic level when material is damaged by arcing in vacuum. Credit: J. Norem, Z. Insepov, Th. Proslier, D. Huang, S. Mahalingam, and S. Veitzer
Most of the arcs people see are a breakdown of the gas between the metal surfaces, but this type of breakdown can also occur in a vacuum. This vacuum breakdown, which until recently has not been well understood, has implications for applications from particle accelerators to fusion reactors.
As part of an effort to understand the maximum accelerating field in particle accelerators, scientists at Argonne National Laboratory have been modeling the processes involved in vacuum breakdown. Now, a new model of this phenomenon is beginning to reveal what is happening in these arcs, and scientists are studying a number of new phenomena associated with them.
In this new model, the breakdown arc is triggered by the electric field in the vacuum gap literally tearing the metal apart. (The same force that causes "static cling" can be very powerful for high electric fields, particularly at tiny corners, and in cracks where the fields are intensified by the local geometry of the surface.) After the metal is torn apart, the fragments should become ionized and form microscopic plasmas that are very dense and cold (for a plasma). Because of the high densities in these plasmas, the surface fields inside the arc quickly become even stronger than they were at breakdown. The arc becomes very damaging to the metal surface over a comparatively large area, eventually leaving a pit that should be visible to the naked eye.
While this model seems to be internally consistent, researchers want to use it to produce predictions that can be verified experimentally. Current research is using molecular dynamics to show what happens at the atomic level when the material is torn apart, plasma modeling codes to show how the plasma initially forms and what its properties are, and electrohydrodynamics to show how the surface of the arc pit is affected. While current results seem generally consistent with existing experimental measurements, more precise tests are being developed.
In principle, a better understanding of the precise causes of electrical breakdown should suggest solutions that are relevant to fusion reactors and space communications, among other things.
Saralyn Stewart | EurekAlert!
From rocks in Colorado, evidence of a 'chaotic solar system'
23.02.2017 | University of Wisconsin-Madison
Prediction: More gas-giants will be found orbiting Sun-like stars
22.02.2017 | Carnegie Institution for Science
On January 15, 2009, Chesley B. Sullenberger was celebrated world-wide: after the two engines had failed due to bird strike, he and his flight crew succeeded after a glide flight with an Airbus A320 in ditching on the Hudson River. All 155 people on board were saved.
On January 15, 2009, Chesley B. Sullenberger was celebrated world-wide: after the two engines had failed due to bird strike, he and his flight crew succeeded...
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
27.02.2017 | Materials Sciences
27.02.2017 | Interdisciplinary Research
27.02.2017 | Life Sciences