Question about Liquid Accelerators

[Interlord1]

I was wondering, how realistic are weapons that accelerate a beam of Molten iron/other metals to high percents of C using magnets. Can you even use magnets on liquids? Would it all bounce around in the barrel destroying it? Etc. If you can answer this, thanks, its been bugging me for hours.

[Eleas]

I was wondering, how realistic are weapons that accelerate a beam of Molten iron/other metals to high percents of C using magnets. Can you even use magnets on liquids? Would it all bounce around in the barrel destroying it? Etc. If you can answer this, thanks, its been bugging me for hours.

With the energy levels involved in accelerating ferromagnetic metals to high fractions of C, you're already looking at liquefaction. You're also looking at insane levels of kinetic energy (impact as well as recoil), meaning the temperature of the impactor would be trivial for damage purposes. You'd ideally want to prevent the projectile from dispersing in any case, meaning you'd want it to be as solid as possible, but at those speeds, my gut tells me it wouldn't be a factor in penetration anyhow.

[Interlord1]

Ah, okay, so what about to speeds like 0.5-1%, I'm wondering because I read somewhere that the reapers on mass effect used "magnetohydrodynamic" weapons which ejects a stream of molten metal at the target.

[adam_grif]

I seem to recall something about magnetic materials losing their magnetism past a certain temperature. Additionally, I have no idea how a liquid or gas would behave in a gauss setup or railgun, and I'm pretty sure solids behave as fluids when they impact at hypervelocity anyway.

EDIT:

Curie temperature

and

Hypervelocity seems to be defined as the point that things behave as fluids for the impact.

[Interlord1]

Okay, thanks.

[adam_grif]

Lol yeah I thought of the Thanix gun when I read your OP.

TBH it's pretty daft, the codex implies that the heat is a non-trivial part of the damage mechanism. I think what happened is (as usual) the cutscene guys rooted up Sovereign's main gun effects in the first game, and then they scrambled to explain why Sovvy used a pew pew gun when the codex said that pew pew guns are shit. So they come up with this "it was firing molten metal at high fractions of C!"

Of course, when you see the guns in action, they are going at extremely low speeds and look just like your standard scifi beam weapons

[Connor MacLeod]

Thanix Cannons as described as behaving (magically) like a shaped-charge weapon, only the velocity is an unknown fraction of lightspeed. Faster than normal mass acceleartor cannon, but that's it. It probably is more like a high mass particle beam (where you use much more massive "ammo" in fewer numbers than a true particle beam. say grains of sand or dust sized or something else.) Like with their normal MACs they achieve the absurd velocities due to their magic "mass effect" fields which "reduce mass but not really reduce it" in a manner much like Andromeda's (but at least the explanation of how/why sounds more plausible here.)

I vaguely recall some 'net articles pointing them to being a tribute (copy) of some old sci fi weapon from some novel (I think Arthur C clarke built it) and being related (loosely) to shaped charge weapons.

[Simon_Jester]

Ah, okay, so what about to speeds like 0.5-1%, I'm wondering because I read somewhere that the reapers on mass effect used "magnetohydrodynamic" weapons which ejects a stream of molten metal at the target.

Even at those energies it doesn't matter. 1% of c translates to about one kiloton of kinetic energy per kilogram of mass in the impactor; the difference between a kilogram of liquid metal and a kilogram of solid metal is nothing compared to that.

Firing solid projectiles without melting them would be the real challenge at those speeds. Heat in the projectile isn't an extra-powerful damage mechanism, it's an undesired side effect you have to either live with or figure out how to get rid of.

And getting rid of it is a problem likely to require a soft-SF solution. If there's a real way to do it, no one's figured it out yet and no one is likely to do it in a way based on technology available today. The material science and power handling technology isn't up to it, not by orders of magnitude.

If you step of from there into the 10% of c range, you might as well think of your 'mass driver' as a particle beam, because the difference between a solid shot and a bolt of dissociated high-energy particles is academic except insofar as the solid shot will hang together better.

This is the one context in which I can imagine a "plasma cannon" as a meaningful concept- with a "plasma cannon" being a mass driver that fires with homicidal indifference to whether the round gets melted/vaporized on the way out the barrel. Whether the increased muzzle velocity would justify the reduced shot cohesion I don't know (I kind of doubt it).

And, again, this is completely a soft-SF concept; you need handwavium materials to handle the stresses involved.

[Stargazer]

Lol yeah I thought of the Thanix gun when I read your OP.

TBH it's pretty daft, the codex implies that the heat is a non-trivial part of the damage mechanism. I think what happened is (as usual) the cutscene guys rooted up Sovereign's main gun effects in the first game, and then they scrambled to explain why Sovvy used a pew pew gun when the codex said that pew pew guns are shit. So they come up with this "it was firing molten metal at high fractions of C!"

Of course, when you see the guns in action, they are going at extremely low speeds and look just like your standard scifi beam weapons

That's...not too unlikely, unfortunately.

[Lord of the Abyss]

I vaguely recall some 'net articles pointing them to being a tribute (copy) of some old sci fi weapon from some novel (I think Arthur C clarke built it) and being related (loosely) to shaped charge weapons.

Yes, in Earthlight. A ship is destroyed by a blast composed of white hot liquid steel; it was actually something of a joke about all those "energy beams" in sci-fi that glow visibly in space. A character even goggles in disbelief at the bright, highly visible beam because it's "impossible", beam weapons don't do that in a vacuum. Interestingly, while Clarke himself considered it impossible due to magnetism weakening under heat as mentioned by adam_grif, it turns out there are ways around that and DARPA is working on a real world version called "MAHEM".

[Sarevok]

Can we please all agree not to use terms like "high fractions of C" ?

[adam_grif]

Can we please all agree not to use terms like "high fractions of C" ?

We aren't given anything more specific for the Thanix, so what are we supposed to say?

[Stargazer]

I vaguely recall some 'net articles pointing them to being a tribute (copy) of some old sci fi weapon from some novel (I think Arthur C clarke built it) and being related (loosely) to shaped charge weapons.

Yes, in Earthlight. A ship is destroyed by a blast composed of white hot liquid steel; it was actually something of a joke about all those "energy beams" in sci-fi that glow visibly in space. A character even goggles in disbelief at the bright, highly visible beam because it's "impossible", beam weapons don't do that in a vacuum. Interestingly, while Clarke himself considered it impossible due to magnetism weakening under heat as mentioned by adam_grif, it turns out there are ways around that and DARPA is working on a real world version called "MAHEM".

That DARPA project is probably what the codex writers for Mass Effect based the Thanix on. They use the same kind of terminology -- magneto hydrodynamic for DARPA, magnetic-hydrodynamic for Mass Effect. As inaccurate as the Mass Effect codex might be at times, they at least do some research on real-world hypothetical technologies to "ground" their technobabble in. For example, one of the writers once referenced Atomic Rockets.

[Simon_Jester]

Can we please all agree not to use terms like "high fractions of C" ?

I use it only for highly-relativistic particle beams, for which I feel I have a right to do so.