- Electrons conduct electricity through copper wires imperfectly because the electron flow continually collides with the atomic lattice structure of the metal they must pass through.
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- Using imperfect conductors requires that an electric potential ( a voltage ) must always be present to push the electrons along. The atomic collisions inside the conductor (resistance ) causes electric energy to transform into heat energy. Heat energy is wasted energy for electric circuits.
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- The idea that electric current could flow through a “ superconductor” without any resistance and without the need for continued electric potential was discovered 100 years ago. Today, it is still a mysterious phenomenon. The potential applications of superconductivity is enormous. Levitate trains, cheap electricity, powerful magnets, etc. The actual applications are still too expensive and very limited. CERN’s particle accelerator uses superconductor magnets at an enormous cost. Why have we not made more progress?
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- The discovery of superconductivity was first made using liquid helium at 4.2 degrees Kelvin.
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- Electricity is the flow of tiny charged particles through the resistance of bouncing off inelastic vibrating atoms. As temperatures go down the vibration of atoms decreases. The resistance to electron flow decreases. As the temperature approaches Absolute Zero, 0 degrees Kelvin, the vibrations nearly stop and the resistance is nearly zero. The material is superconducting.
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- In April 1911 this experiment was tried using liquid mercury. Sure enough at 4.2 Kelvin mercury has zero electrical resistance. Once current was flowing it would flow continuously without adding energy. Once started it would still be flowing today, 100 years later. Of course, only if kept at the extremely low temperatures of liquid helium, which is expensive.
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- Later it was discovered that superconductivity in lead was even easier to maintain at 7.2 Kelvin.
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- Superconductivity found in these simple metals occurred in only a micron of the metal’s surface. The electric current was easily stopped by the influence of any external magnetic field. However, if the superconductor was cooled below a critical temperature the magnetic field lines were expelled from penetrating the conductor. Magnetic field lines could only flow around the conductor and not inside it.
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- The explanations for these strange phenomena was not completed until 1972. The theory was that a gas of electrons are unstable in the presence of small, infinitesimal, attractive interactions. This causes the electrons to bind together in pairs, called “ Cooper Pairs”. The small , infinitesimal, attractive interactions were discovered to be “ phonons” Phonons are like sound waves in the metal that were at a resonant frequency. This allowed conduction of electron pairs at zero resistance. Phonon frequencies of oscillations are typically trillions of cycles per second.
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- The theory stated the pairing of two fermions were mediated by a boson field. The theory explains why sodium, gold, silver, and copper are not good superconductors, but lead is.
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- It was not until 1986 that the theory advanced using layered copper-oxide having zero resistance at 30 Kelvin. In 1987 yttrium-barium- copper-oxide would super conduct at 93 Kelvin. This is 16k above the boiling point of liquid nitrogen. Finally a cheaper cryogen could be used instead of expensive liquid helium. The record for some new exotic materials is up to 138 Kelvin for superconductivity.
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- Many demonstrations of successful power cables, transformers, generators, fault-current limiters, using superconductivity have been made. The technology is proven. The economics are not proven.
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- Magnesium Diboride (MgB2) super conducts at 39K.
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- CERN’s LHC uses superconducting magnets of niobium-titanium alloys. Today MgB2 would have been a better choice.
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- Superconductivity likely exists in the interior of Neutron Stars where fermonic quarks and gluon bosons reach a superconducting transition at 1,000,000,000 Kelvin. That is hot. A middle ground temperature would sure be nice. What we still need is a common, cheap material that will superconductor at 300 Kelvin. An announcement will be made shortly, stay tuned.
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RSVP, please reply with a number to rate this review: #1- learned something new. #2 - Didn’t read it. #3- very interesting. #4- Send another review #___ from the index. #5- Keep em coming. #6- I forwarded copies to some friends. #7- Don‘t send me these anymore! #8- I am forwarding you some questions? Index is available with email and with requested reviews at http://jdetrick.blogspot.com/ Please send feedback, corrections, or recommended improvements to: jamesdetrick@comcast.net. ---- “Jim Detrick” -- www.facebook.com, -- www.twitter.com, -- 707-536-3272 Thursday, December 27, 2012
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