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August 1964 Radio-Electronics
 [Table of Contents]
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Electronics,
published 1930-1988. All copyrights hereby acknowledged.
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The history of
superconductors
spans over a century, beginning in 1919 with the discovery by Heike Kamerlingh Onnes, and has led to significant advancements in the field of
physics and technology. A superconductor is a material that exhibits zero
electrical resistance and the expulsion of magnetic fields when it is cooled
below a critical temperature. In other words, it can conduct electric current
without any loss of energy due to resistance, and it can also expel magnetic
fields from its interior. This phenomenon is known as superconductivity.
Superconductors have numerous practical applications, including in the
construction of powerful magnets for medical devices like MRI machines,
high-speed electronic circuits, and potentially even in energy transmission and
storage systems. Superconductivity is a quantum mechanical phenomenon that was
first discovered in certain metals and has since been observed in various
materials, including ceramics and some specialized compounds. This "The 1960's - Superconductivity's Decade?"
article from a 1964 issue of Radio-Electronics magazine is an
optimistic view of the state of the art at the time. Sixty years later, we're
still not really "there" with superconductors.
The 1960's - Superconductivity's Decade?
Detail of RCA's mighty supermagnet shown in the photo.
By Eric Leslie
As the 1940's were marked by the transistor; the 50's by discovery of the maser-laser,
so may progress in the 1960's be linked with the phenomenon of superconductivity.
Already it is suggested that it may be instrumental in "achieving an exotic generation
of high-performance computers, microwave radar and communications equipment, magnets,
scientific instruments, high-current storage batteries, magnetohydrodynamic power
supplies, and propulsion systems for outer space." The fact is that superconductivity
is still so new in application that, like the laser in the 1950's, its possible
applications are still largely unknown.
When this superconducting magnet "went normal" (out of superconductivity), fantastic
power of magnet pleated heat-absorbing copper sheet around center of magnet winding.
Magnet still worked after that! Light-colored flat ribbon above and below accordion-pleated
copper is niobium-tin alloy winding, which becomes superconducting at low temperatures.
Wrinkled flat strips at top of winding form are connecting leads.
Unlike the laser and the transistor, which were absolutely new when brought to
public attention, the principles of superconductivity have been known for many years.
In 1911, Kammerlingh Onnes, experimenting with the production of extreme cold, discovered
that certain metals lost all their resistance when lowered to the temperature of
liquid helium (4° K approximately) .
Not much use was made of this phenomenon for many years, for the simple reason
that the magnetic field set up by any great amount of current through the superconductor
would cause the superconductivity to disappear immediately. In recent years new
superconductive materials, "hard superconductors", have been found that will work
at higher temperatures and higher currents.
A niobium-tin mixture has the greatest ability in this direction, but until recently
was so brittle that it could not be made into usable conductors. A number of processes
have been developed for using the niobium-tin compound. Possibly the most successful
is that of Dr. J. J. Hanak, of RCA Laboratories, who evaporates niobium stannide
on a stainless-steel ribbon.
A magnet made of ribbon produced by this process was demonstrated at the David
Sarnoff Research Laboratories recently. A field of 107 kilogauss makes it one of
the strongest magnets of the world; yet it is only about 6 inches in diameter and
uses a fantastically small fraction of the power required by other magnets of similar
type.
Specifications of the RCA 107-Kilogauss Magnet
At the same demonstration, RCA showed a microwave amplifier that uses superconductivity
to work in the gigacycle frequency range, a superconductive computer memory and
a high-speed electronic switching system usable in computers.
All these devices, of course, depend on operating at extremely low temperatures.
Other companies are developing the necessary "refrigerators" which will make it
possible to handle such cryogenic devices efficiently and economically.
Posted September 15, 2023
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