On Mon, Mar 27, 2017 at 2:47 PM, (via tml list) <xxxxxx@simplelists.com> wrote:
> On 25 Mar 2017 at 17:28, Jeffrey Schwartz wrote:
>
>> On Sat, Mar 25, 2017 at 2:54 PM, (via tml list)
>> <xxxxxx@simplelists.com> wrote: > >> If it requires the services of a
>> starport - of at least grade C - and >> it's the _starport_ that needs
>> to be jumpstarted with the jump plant, >> you've got an ...
>> interesting ... situation... > > Even ignoring that, consider what
>> sort of cables you'd need to handle > that much power! >
>>
>> Traveller has room temp superconductors, which would help quite a bit
>> in that regard.
>
> Not as much as you might think.
>
> superconductors have *three* "critical" values to worry about.
>
> Critical temp: above this they aren't superconducting anymore
>
> Critical current: get more amps than this flowing and it quits being
> a superconductor. And a short time later it will explosively
> vaporize.
>
> Critical field: If the magnetic field strength exceeds this, it quits
> being a superconductor.
>
> When you are running massive amounts of power thru the cable, *any*
> of those happening will result in a positive feedback loop as the
> cable goes from zero resistance to rather high resistance. which
> increases the temp which increases the resistance which...
>
> Like I said, positive feedback loop. With an end result of "Boom" as
> the cable explosively vaporizes.
>

Understood.

On the other hand, even the lowly Type-S can handle 500Mw on a
flexible link coming into the turret.... so I strongly suspect that
the critical thresholds for those three factors are fairly high at
TL13+

PGMP's, FGMP's, and Gauss weapons are routinely used in pretty warm
environments, and are rated for the sun-side of the outside of a
spacecraft for boarding actions. If those superconductors work, I
suspect that the critical temp is much higher than most of us would
expect. if we're looking at a ship jump starting another ship, then
the worst case would be in orbit, with the sun shining on it... and
that's something those hand-held devices cope with. I suspect a
purpose built set of jumper cables would have mechanisms for handling
the issue. After all, they've been doing this for 2000 years.

A culture that can make handheld gauss weapons probably has a pretty
good understanding of magnetic fields, and the critical field issue
shouldn't be a surprise to them.

Critical current... I suspect that there's work arounds here as well.
Off the top of my head is upping the voltage to something truly
outrageous, and having some sort of step down transformer at the other
end. I suspect that developing a superconducting transformer would
involve some interesting math given the aforementioned critical field
issue, but if you can handle 500Mw in the close confined of a Type-S,
then your culture probably has a good handle on that.