Deborah D L Chung
Deborah D. L. Chung
|Born||Template:Error Template:ErrorDecember 0, 1950|
|Residence||East Amherst, NY, United States|
|Known for||Negative Resistance|
In July 1998, Deborah Chung and Shoukai Wang of the University of Buffalo presented the results of an experiment that showed an apparent absolute negative resistance in bare carbon fibers held together by pressure.
In the experiment, two bundles of carbon fibers are arranged in a cross shape, with the ends of each bundle shorted with copper foil and silver paint (at A, B, C, and D in the image). A current is driven through one branch, and a voltage is measured across the other branch. In the paper, the voltage divided by current is referred to as an "apparent resistance". (A real electrical resistance requires both the current and voltage to be measured at the same points.)
The paper describes how the apparent contact resistance of the interface changes from positive to negative when the fibers are compressed. The current-voltage characteristic of the measured "negative resistance" is then a straight line of negative slope through the origin. The apparent negative resistance was also observed in metal wires (silver-coated copper), but was not observed for a single fiber crossing another single fiber. The paper claims that this phenomenon is useful because the forward flow and backflow of electrons in the same piece of material can be reproducibly controlled by external forces.
It was initially reported on July 9, 1998 by the University as a breakthrough in room temperature superconductor research, in the press release Superconduction At Room Temperature: Negative Electrical Resistance Seen In Carbon Composites, claiming that the discoveries "have enabled carbon-fiber materials to superconduct at room temperature", because of measurements of "zero apparent resistance" at certain pressures. This was quickly seized upon by the free energy community as a working example of a device that supplies energy with no apparent source, claiming it to be a true, absolute negative resistance, and was reported in the popular press as a breakthrough. The original press release was later pulled from UB's website, on July 16, 1998, and replaced with one which stated "her findings do not indicate that the combination is itself a superconductor."
Chung's paper itself says:
True negative resistance in the former sense is not possible due to energy consideration. However, apparent negative resistance in the former sense is reported here. ... Although the negative resistance reported here is apparent rather than true, its mechanism resembles that of true negative resistance (which actually does not occur due to energetics) in that the electrons flow in the unexpected direction relative to the applied current/voltage.
Wang, Chung, Apparent negative electrical resistance in carbon fiber composite
Chung Negative Resistor Experiment