Zeroue Effect Phenomena?
dwenbert ( (no email) )
Mon, 22 Jun 1998 04:15:09 -0400
----------
> From: dwenbert <dwenbert@spacey.net>
> To: Newman-L Mailing List <newman-l@emachine.com>
> Cc: freenrg-l@eskimo.com
> Subject: Re: Is pulse timing 50% incorrect?
> Date: Monday, June 22, 1998 3:58 AM
>
> The following article describes recent discoveries which have a direct
> bearing on several aspects of Newman's research and other zeroue devices.
> One theory, that superconductance occurs around/along the periphery of
the
> wires in a wound copper core under certain circumstances is borne out by
> the work done at GIT, in re: phenomena observed inside carbon fibers.
This
> is interesting because if true -- that Newmanesque devices benefit from
a
> gratuitous [magnetic field expelling] surface Meisner effect occasioned
by
> superconductive eddy currents along the copper core -- then, the
anomalous
> thermal properties of these zeroue devices [where what 'should' exhibit
> resistive heating is instead found cooling to below ambient temperature]
> are explainable in terms of the adiabatic paramagnetic thermal convection
> that such a laminar surface current flow would produce....
>
>
> ----- Dave W.
>
> Source: Georgia Institute Of Technology
> Posted 6/18/98
>
> Tiny Computers Of Carbon? Nanotubes That Conduct Huge Currents Without
> Heating Could Be Basis For New Electronics
>
> A report to be published in the June 12 issue of the journal Science
moves
> researchers one step closer to a practical application for electron wave
> effects in extremely small-scale circuits.
>
> In the paper, a team of scientists from the Georgia Institute of
Technology
> reports observing ballistic conductance -- a phenomenon in which
electrons
> pass through a conductor without heating it -- at room temperature in
> multi-walled carbon nanotubes up to five microns long. (A micron is a
> millionth of a meter).
>
> Structures of that size operating under those conditions could one day be
> useful for fabricating ever-smaller electronic devices. Their ability to
> conduct relatively large currents without harmful resistance heating
would
> allow use of the very small conductors.
>
> "This is the first time that ballistic conductance has been seen at any
> temperature in a three dimensional system of this scale," said Dr. Walt
de
> Heer, a professor in Georgia Tech's School of Physics. "There would be
> interest in this for ultra-small electronics, because it shows that you
can
> constrain current flows to narrow areas without heating up the
electronics.
> It also introduces a new stage of electronics in which the wave nature of
> electrons becomes important."
>
> In a simple experimental design using the positioning equipment of an
> atomic force microscope, the researchers found that the electrical
> resistance of the multi walled carbon nanotubes remained constant --
> regardless of their length or width. This quantum conductance is not seen
> in larger structures.
>
> "In classical physics, the resistance of a metal bar is proportional to
its
> length," said Dr. Z.L. Wang, a professor in Georgia Tech's School of
> Materials Science and Engineering. "If you make it twice as long, you
will
> have twice as much resistance. But for these nanotubes, it makes no
> difference whether they are long or short because the resistance is
> independent of the length or the diameter."
>
> That's possible, explained de Heer, because the electrons act more like
> waves than particles in structures whose size approaches that of the
> wavelength of electrons. "The electrons are passing through these
nanotubes
> as if they were light waves passing through an optical waveguide," he
said.
> "It's more like optics than electronics."
>
> In normal wires, the electrical energy they carry dissipates in the
> conductor, but in the nanotubes, energy dissipates only in the leads used
> to connect the tubes. Such effects had previously been seen only in
> structures a thousand times smaller, and finding them in the
comparatively
> large nanotubes was "quite surprising," de Heer said.
>
> "Until now, these effects were considered to be exotic and seen only
under
> very special conditions," he said. "Now we are seeing them abundantly and
> easily at room temperature with very simple devices."
>
> The absence of heating allows extremely large current densities to flow
> through the nanotubes. Wang and de Heer measured current densities
greater
> than ten million amperes per square centimeter. Normal resistance heating
> would have generated temperatures of 20,000 K in the nanotubes, well
beyond
> their combustion temperature of 700 K.
>
> Though they these effects were measured only in nanotubes of less than
five
> microns, such current densities are far greater than could be handled by
> any other conductor, Wang noted. At lengths of more than five microns,
> however, de Heer believes electron scattering may defeat the ballistic
> conductance effect.
>
> "We can only guarantee that we can carry that kind of current over five
> microns," he said. "We don't know what will happen if you try to conduct
> for longer distances. This will certainly not be a way to transport
current
> over large distances."
>
> In their laboratory, de Heer, Wang and collaborators Stefan Frank and
> Philippe Poncharal attached a tiny electrode to a bundle of nanotubes
that
> had a single long tube protruding from one end. They mounted the bundle
in
> place of the probe normally used in an atomic force microscope and
> connected a battery to the electrode.
>
> They then used the microscope controls to raise and lower the single
> protruding nanotube into and out of a pool of mercury that served to
> complete the circuit back to the battery. The resistance they measured as
> the nanotube was raised and lowered into the mercury remained constant,
> changing only when a shorter tube protruding from the bundle -- which
> resembles a handful of straw -- made contact with the liquid metal.
>
> The researchers measured the resistance of 20 nanotubes of different
> lengths and diameters through as many as 1,000 cycles that consisted of
> dipping them in and out of mercury and two other molten metals -- gallium
> and Cerrolow-117. The tubes averaged 15 nanometers wide and four microns
> long, but ranged from one to five microns in length, with diameters from
> 1.4 nanometers to 50 nanometers. The quantum of resistance remained 12.9
> kiliohms.
>
> Despite the importance of the discovery, de Heer cautions that electronic
> devices using nanotube conductors are perhaps decades away. One
fundamental
> issue is that carbon materials are incompatible with the silicon that is
> the basis of current integrated circuits. Solving that challenge will
> require a revolution in electronic design.
>
> "It would be like introducing silicon transistors during the age of
vacuum
> tubes," he said. "You couldn't combine the two because they are from
> different worlds. This just opens the door, it doesn't tell you how to
> build a better world. This should be seen as the proof of principle
showing
> that we can do ballistic conductance at room temperature."
>
> The researchers hope to follow up their work with measurements of other
> predicted device properties of the nanotubes. The research is sponsored
by
> the U.S. Army Research Office and the Georgia Tech Foundation.
> Copyright (c) 1995-97 ScienceDaily Magazine. E-mail: Dan Hogan,
> editor@sciencedaily.com
>