On Mon, Mar 27, 2017 at 11:47:43AM -0700,  (via tml list) 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.

Quite a few TL7 superconductors can easily handle kiloamp currents per
square millimetre in tens of tesla magnetic fields.  A reasonably
thick cable could carry a million amps, while still remaining well
within magnetic field limits throughout.  With good insulation it
could maintain a potential of ten thousand volts -- probably quite a
lot more with advanced materials science, but let's leave a very wide
safety margin.

So carrying a few tens of gigawatts should not be ridiculously
difficult given room-temperature superconductors that are otherwise
similar to our own liquid helium superconductors.

In case of failure, it might not even go boom.  A superconducting
cable like the above would have strong magnetic fields, but confined
mostly within the cable itself.  The energy would be on the order of a
couple hundred kilojoules per metre of cable.  Probably not even
enough to melt it if the field collapses unexpectedly, let alone
explode, but there would certainly be many other related hazards.

Real-world superconductor failures tend to be explosive since they are
almost always used to generate intense magnetic fields throughout a
volume much larger than the superconductor itself, and so storing
greatly more energy.  In a failure situation all that energy gets
dumped into nearby conductors, including the no longer superconducting
coils.

- Tim