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Post by n2maniac on Dec 15, 2016 7:27:51 GMT
Looking at the effectiveness of the multi-GW lasers people here have made, I started wondering about light-like beams that can be made more efficiently than laser light yet still focused down. Then I remembered why electron microscopes are used (the small wavelength of fast electrons makes diffraction limited optics no longer a limit), that electron beam welding is a thing, and wondered about projecting a beam of charged particles at a far away target. A quick pro/con list: + Particle charge * acceleration voltage = particle energy, no obvious loss mechanisms + Electron rest mass is low enough that 1 MV (megavolt) acceleration voltage yields gamma ~ 3 (v=0.89 c) + Dielectric breakdown is limited only to the insulation's capability in space. An object a meter long could provide 10s of MV of acceleration without needing complicated insulation schemes, as opposed to a few MV in air on Earth. + Fine focusing can be 100% electronic. No pesky mass in mirrors to move! ? Relativistic electrons have nonzero penetrating capability and tend to cause the target to emit X-rays. May damage internals easier, but also may leave armor more intact. ? The beam will interact with the magnetic fields of nearby planets and the solar wind to some extent (not sure this is problematic over a few 10s or 100s of km). - The beam will repel itself, attempting to defocus as it flies farther. Higher electron speeds somewhat alleviate. - Hitting a target with such a beam will charge it, preventing further hits unless a positive ion beam is also fired.
Firing the beam randomly into space will charge the ship firing it, attracting electron beams (including the one fired at some point) and charged particles. May act as a countermeasure? ? An insulated target hit with this will build up charge and dangerous voltages inside the insulator, eventually discharging violently. What has been looked at before? Well, the SDI program looked into this apparently. Apparently, the bolded problems above were bad enough that neutral beams were preferred. Preferred enough to launch a neutral hydrogen beam emitter into space. (Worth noting: poor beam divergence on that flight article (~1mrad). Dunno how fixable that is with the design). Thoughts from anyone else on this type of thing?
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Post by goduranus on Dec 15, 2016 7:49:49 GMT
Make MPDs into plamsa cannons!
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Post by The Astronomer on Dec 15, 2016 12:17:57 GMT
Looking at the effectiveness of the multi-GW lasers people here have made, I started wondering about light-like beams that can be made more efficiently than laser light yet still focused down. Then I remembered why electron microscopes are used (the small wavelength of fast electrons makes diffraction limited optics no longer a limit), that electron beam welding is a thing, and wondered about projecting a beam of charged particles at a far away target. A quick pro/con list: + Particle charge * acceleration voltage = particle energy, no obvious loss mechanisms + Electron rest mass is low enough that 1 MV (megavolt) acceleration voltage yields gamma ~ 3 (v=0.89 c) + Dielectric breakdown is limited only to the insulation's capability in space. An object a meter long could provide 10s of MV of acceleration without needing complicated insulation schemes, as opposed to a few MV in air on Earth. + Fine focusing can be 100% electronic. No pesky mass in mirrors to move! ? Relativistic electrons have nonzero penetrating capability and tend to cause the target to emit X-rays. May damage internals easier, but also may leave armor more intact. ? The beam will interact with the magnetic fields of nearby planets and the solar wind to some extent (not sure this is problematic over a few 10s or 100s of km). - The beam will repel itself, attempting to defocus as it flies farther. Higher electron speeds somewhat alleviate. - Hitting a target with such a beam will charge it, preventing further hits unless a positive ion beam is also fired.
Firing the beam randomly into space will charge the ship firing it, attracting electron beams (including the one fired at some point) and charged particles. May act as a countermeasure? ? An insulated target hit with this will build up charge and dangerous voltages inside the insulator, eventually discharging violently. What has been looked at before? Well, the SDI program looked into this apparently. Apparently, the bolded problems above were bad enough that neutral beams were preferred. Preferred enough to launch a neutral hydrogen beam emitter into space. (Worth noting: poor beam divergence on that flight article (~1mrad). Dunno how fixable that is with the design). Thoughts from anyone else on this type of thing? If this thing has a real world formula, it might be implemented, or at least, a cool mod.
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Post by wafflestoo on Dec 15, 2016 23:11:20 GMT
Or you pair a beta-PAWS and an alpha-PAWS together to alleviate a lot of the ion charge and beam defocusing problems... plus it would generate a massive arc through the target between the two impact points. I imagine that would play havoc on a ship's electronics systems.
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Post by lawson on Dec 16, 2016 1:37:17 GMT
Or you pair a beta-PAWS and an alpha-PAWS together to alleviate a lot of the ion charge and beam defocusing problems... plus it would generate a massive arc through the target between the two impact points. I imagine that would play havoc on a ship's electronics systems. And if the beams were close enough together and slightly skewed, The two beams would orbit each other. Even if particle beams aren't very long range, I bet they'd make great point-defense weapons.
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Post by goduranus on Dec 16, 2016 5:24:45 GMT
This may not surprise real engineers but I just realized the MPDs in game are toroid plasma railguns, with cathode and anode being the two rails and the plasma being the armature.
Can this actually be used as a gun?
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Post by n2maniac on Dec 16, 2016 7:33:46 GMT
This may not surprise real engineers but I just realized the MPDs in game are toroid plasma railguns, with cathode and anode being the two rails and the plasma being the armature. Can this actually be used as a gun? Huh, did not realize. That makes a lot more sense as to the shape. The plasma will disperse in space dependent at a rate dependent on its internal plasma temperature, magnetic field properties, and launch velocity. This would create a diverging beam. If the beam were narrow enough, certainly would be a weapon. Rough calculations imply divergence is awful unless the magnetic field properties of the torus keep it together really well (invalidating my naive ideal gas assumption) or launch velocities greater than 1Mm/s were used.
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Post by goduranus on Dec 16, 2016 9:05:23 GMT
Shrink the plasma torus with an induction coilgun, stuck at the exit end?
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Post by wafflestoo on Dec 16, 2016 22:03:18 GMT
Or you pair a beta-PAWS and an alpha-PAWS together to alleviate a lot of the ion charge and beam defocusing problems... plus it would generate a massive arc through the target between the two impact points. I imagine that would play havoc on a ship's electronics systems. And if the beams were close enough together and slightly skewed, The two beams would orbit each other. Even if particle beams aren't very long range, I bet they'd make great point-defense weapons. Why am I suddenly picturing the battery cannons on the Yamato from 'Star Blazers'?
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Post by goduranus on Dec 17, 2016 4:46:55 GMT
I always thought those were weird. But maybe those are matter-antimatter beams, else one of the beams would spiral around a lot more than the other.
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Post by wafflestoo on Dec 17, 2016 6:21:50 GMT
I searched for longer than I care to admit, but I remember a few scenes where the two beams on the outer edges of the turret wound very tightly around the center beam cannon in a pattern roughly what you are describing... but I can't even remember what season that happened in; let alone the specific episode.
(also, I love how often hubris unwound the OPFOR's plots XD. It also probably didn't hurt that the Yamato was one tough SOB that could; and quite often did take a serious beating)
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Post by aetreus on Dec 18, 2016 5:36:39 GMT
This may not surprise real engineers but I just realized the MPDs in game are toroid plasma railguns, with cathode and anode being the two rails and the plasma being the armature. Can this actually be used as a gun? Huh, did not realize. That makes a lot more sense as to the shape. The plasma will disperse in space dependent at a rate dependent on its internal plasma temperature, magnetic field properties, and launch velocity. This would create a diverging beam. If the beam were narrow enough, certainly would be a weapon. Rough calculations imply divergence is awful unless the magnetic field properties of the torus keep it together really well (invalidating my naive ideal gas assumption) or launch velocities greater than 1Mm/s were used. It's possible to make a torus that binds itself pretty well, at least when the plasma involved is not particularly hot. Apparently there was enough possibility of actually firing these out of an accelerator that it was considered as a BMD technology.
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Post by morrigi on Jan 4, 2017 14:31:28 GMT
Huh, did not realize. That makes a lot more sense as to the shape. The plasma will disperse in space dependent at a rate dependent on its internal plasma temperature, magnetic field properties, and launch velocity. This would create a diverging beam. If the beam were narrow enough, certainly would be a weapon. Rough calculations imply divergence is awful unless the magnetic field properties of the torus keep it together really well (invalidating my naive ideal gas assumption) or launch velocities greater than 1Mm/s were used. It's possible to make a torus that binds itself pretty well, at least when the plasma involved is not particularly hot. Apparently there was enough possibility of actually firing these out of an accelerator that it was considered as a BMD technology. The U.S. government had a program to weaponize the technology back in the 90's, but the program dropped off the face of the earth.
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Post by n2maniac on Jan 6, 2017 7:18:01 GMT
Huh, did not realize. That makes a lot more sense as to the shape. The plasma will disperse in space dependent at a rate dependent on its internal plasma temperature, magnetic field properties, and launch velocity. This would create a diverging beam. If the beam were narrow enough, certainly would be a weapon. Rough calculations imply divergence is awful unless the magnetic field properties of the torus keep it together really well (invalidating my naive ideal gas assumption) or launch velocities greater than 1Mm/s were used. It's possible to make a torus that binds itself pretty well, at least when the plasma involved is not particularly hot. Apparently there was enough possibility of actually firing these out of an accelerator that it was considered as a BMD technology. Awesome. I wonder if there are any public papers on this topic (or someone with more plasma physics experience than I do)? Weaponization papers might not be easy to find, but I would bet there might be some fusion-related ones particularly since at least one company is banking on that working for them.
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qstl
New Member
Posts: 4
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Post by qstl on Jan 8, 2017 10:21:20 GMT
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