I would say that a vacuum is a pretty good insulator, not semiconductor. No
free carrier density in a vacuum.
Also, a superconductor has a critical temperature, a critical current
Density, and a critical magnetic field, which is generally considered to be
Hc2 since most commercially used superconducting wires are made of Type 2
superconductors. For magnetic fields greater than Hc2, there are no more
superconducting regions in the material.
By the way, some of you may be interested in knowing that Richard Hake did
some of the major early work on high field superconductors before he became
an physics education researcher.
Larry Woolf; General Atomics; 3550 General Atomics Court, San Diego, CA
92121; Phone:858-455-4475; FAX:858-455-4268; http://www.sci-ed-ga.org
-----Original Message-----
From: John S. Denker
At 01:06 PM 1/8/02 -0800, Bernard Cleyet wrote:
I thought the best superconductor was a vacuum (no crit. B, etc.)
Huh?
I don't see the slightest similarity between a vacuum and
a superconductor. How, for instance, would you set up
a persistent current?
And what means "no crit B"? Does that mean zero critical
field (i.e. not a superconductor at all) or does it mean
infinite critical field?
A vacuum is in some respects a pretty good _semi_conductor, but
that's a horse of a different color entirely.