UFO:AI, my comments and criticisms

[Grotus]

Perhaps the plastic shell has an extremely complex system of minaturized electromagnets that keeps the plasma together for a fraction of a second.

I like you idea but not its hilarious complexity. Just have the material have an inherent charge. You know, like a fridge magnet, but orders of magnitude stronger.

It doesn't have to be complex, what would plasma do in a shell of superconductive material?  If the superconductive shell wouldn't do the trick by itself, pattern rings of superconductor around the plastic shell, charge them up and you've got a magnetic bottle.  The superconductors wouldn't even have to be too high-temperature, just chill the plastic enough to keep them superconducting until they hit the target.

[blondandy]

I guess you mean use supercondunctors to create the strong magnetic field (like in an MRI scanner).

problem is that you need to be at liquid nitrogen temperatures for superconductivity. you could postulate that the problem of room temp superconductivity has been solved by clever aliens.

it is still complex

[Winter]

It doesn't have to be complex, what would plasma do in a shell of superconductive material?  If the superconductive shell wouldn't do the trick by itself, pattern rings of superconductor around the plastic shell, charge them up and you've got a magnetic bottle.  The superconductors wouldn't even have to be too high-temperature, just chill the plastic enough to keep them superconducting until they hit the target.

Please offer some evidence in support of this theory, I think it's very interesting. I'm sure the aliens could come up with technology to 'flash-freeze' a ball of plastic to superconducting temperatures. The breaking of such a frozen ball against a target would help to keep the plasma on the target instead of dispersing, as well.

Mind you, keeping something so cold whilst containing a mass of superheated plasma seems . . . unlikely.

With regards to room-temperature superconductors, if we give them to the aliens then there are a lot of possible weapons and equipment technologies that they could/should have of which I've never even heard. We'd need more technical expertise to help us out.

Regards,
Winter

[Adrian Magnus]

The aliens having room temperature superconductors would help explain their particle beam weaponry. The energy requirements for accelerating even sub-atomic particles to c-fractional velocities is non-trivial. A superconductor that doesn't need to be super-cooled would allow for high energy density storage which in turn would make it possible to power a pocket particle accelerator.

Regarding the plasma thing, the more minimalist the explanation the better. The weapon is implausible as is so we might as well just put in a short explanation to minimize hand-waving. Say "the plasma is encased in a bubble of a magnetically charged material" and leave it at that. The short range is explained by either the material (or plastic if you like) being stable for only a short about of time, or it rapidly losing its charge. Going about explaining just exactly what the material is, and how it is magnetically charged, or even saying the word "superconductor", is asking for the death of the audience's suspension of disbelief.

It's a good rule of thumb to minimize handwavium whenever possible.

[Grotus]

According to www.superconductors.org, the current world record is 138K, with a potential 150K compound in the works.  This is already significantly better than liquid nitrogen (77K), I would expect that even us feeble humans would be able to better than that given the next 77 years to work on it.

The whole point to using a superconductor would be to keep the hot plasma away from the container, so not a whole lot of heat transfer from the plasma would happen.  There would be radiant heat transfer, but no conduction.

[blondandy]

room temp superconductor, or some fanct cooling
superconductor makes strong electric current.
current creates magnetic field
field contains plasma
plasma does not need to touch physical container
a container is still required to stop air entering plasma containment field and scattering plasma, while the projectile is is flight.

i don't like the phrase "magnetic charge". it suggests magnetic monopoles, which are impossible.

[MDA]

Is there anyting preventing you having the plasma generated at the point of impact instead of within the weapon itself?  Something similar to a conventional shaped charge/hollow round?  

As far as design goes, it would solve the problem of plasma weapons being attenuated by smoke as well and would have armor-piercing capability.  Small rifle-sized rounds with miniaturized components capable of forming a jet of subatomic gunk instead of molten metal on impact.  
Punching a hole in heat resistant armor and delivering heat inside it where its actually contained by the armor would be pretty devastating.

I guess that changes the whole weapon mechanic, but its something.

http://en.wikipedia.org/wiki/Shaped_charge