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Re: non-dissipative circuitry



In the context of non-dissipative switching,
with a nonzero voltage across the switch,
Ludwik Kowalski wrote:

Since we are "gedankening" let me observe that there should be no
spaaaakking in a "perfect vacuuuuum," i.e. in space without atoms.

I don't think you can avoid dissipation just
by switching in a vacuum.

In practice, if you have a perfect vacuum at
the beginning of the experiment, you won't at
the end, or at the relevant middle.

There is such a thing as corona. If (when!)
the field gets big enough, it will rip electrons
out of whatever material the switch is made of.
These electrons will accelerate through the
vacuum and hit the other electrode with a lot
of energy.

Even if the voltage is small enough that the
electrons won't vaporize the material where
they hit, the electrons will be injected into
bands far, far from where the supercurrent lives.
So at best you will have a two-fluid model, with
some supercurrent and some normal current. The
latter will be dissipative.

If you really think you can build a non-dissipative
switch (that closes against nonzero voltage and/or
opens against nonzero current) you'll need to
describe it in a lot more detail if you want me
to understand it.