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09-06-2017, 08:34 PM | #11 |
Join Date: May 2010
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Re: [Ultra-Tech] [Spaceships] Weapons that are hard or impossible to miniaturize
Sorry, there was a typo in the original post that mangled the question. If I'm reading the equations on Wikipedia right, going from say 1nm to 0.1nm requires an FEL 10 times as long, correct?
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09-06-2017, 08:38 PM | #12 |
Join Date: May 2010
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Re: [Ultra-Tech] [Spaceships] Weapons that are hard or impossible to miniaturize
The whole Spaceships line assumes they're uncommon, though. Two miles translates to SM +19 or +20, which is easy enough to extrapolate but which we have no worked examples of. Even the suggestion for turning an Adversary-class warship into a planet-killer using cosmic power only uses SM+18.
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09-06-2017, 08:49 PM | #13 | |
Join Date: Aug 2007
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Re: [Ultra-Tech] [Spaceships] Weapons that are hard or impossible to miniaturize
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09-06-2017, 09:34 PM | #14 | ||||
Join Date: Nov 2004
Location: The plutonium rich regions of Washington State
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Re: [Ultra-Tech] [Spaceships] Weapons that are hard or impossible to miniaturize
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https://en.wikipedia.org/wiki/Plasma_acceleration We're still working out some of the kinks at TL 8 - we can get particle energies of a GeV in a few cm, but the emittance may not be tight enough to be usable as a spacecraft-to-spacecraft weapon. Also, the theoretical maximum amount of energy you can transfer from your laser pulse to a particle bunch is 50%, in practice current wakefield accelerators are more like 10% to 20%. At this point you need to ask yourself if you should just use that laser to fry your enemies instead. If you use the particle beam from a wakefield accelerator to drive an x-ray free electron laser, you can get around the emittance problems - FELs self-organize their electron bunches to draw energy from the particles and transfer it to the x-ray field. Quote:
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We don't have gamma ray lasers, but you can use particle beams to get narrow gamma ray beams using laser Compton backscatter (in principle, you can also use positron annihilation in flight, but that's a tech path that we are not currently pursuing in favor of Compton backscatter). Quote:
https://en.wikipedia.org/wiki/Halbach_array This forces the electrons to move in a sinusoidal pattern. The modes of the electromagnetic field whose force is constantly opposing the motion of the electrons will have work done on them and be amplified. With a suitably long wiggler or a resonant cavity, you can get a very narrow band of modes, like a laser beam. If the radiation field is intense enough and the wiggler is long enough, the electrons will self-organize into bunches to produce super-radiant coherent motion. Now you have a free electron laser. For a tuneable FEL, you will need separate wigglers for different frequency bands. The wiggler for the x-rays will have a pitch way too short for when you need visible light, so you would divert the electron bunches to a visible light wiggler. (The visible light wiggler would probably also be inside a Fabry-Perot resonant cavity, https://en.wikipedia.org/wiki/Fabry%...interferometer allowing you to achieve your laser behavior threshold with a much shorter wiggler.) Luke |
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09-07-2017, 09:27 AM | #15 |
Join Date: May 2010
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Re: [Ultra-Tech] [Spaceships] Weapons that are hard or impossible to miniaturize
I'd forgotten the thing about streamlined ships, but the lengths in the table are for "typical cylinders". There's no indication you can stretch them out significantly beyond what's in the table without the same DR handicap streamlined ships face. Note: two miles is 3,520 yards. SM+19 is 3,000 yards, while SM+20 is 5,000 yards. An SM+18 ship that was two miles long would be 175% of the typical length for an unstreamlined ship, which I think would be an issue for DR.
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09-07-2017, 09:34 AM | #16 |
Join Date: May 2010
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Re: [Ultra-Tech] [Spaceships] Weapons that are hard or impossible to miniaturize
Assuming a loaded spaceship has the same density as water (which probably overestimates the volume of a warship), a two-mile long cylindrical SM+18 ship would only have a radius of 100 yards. I guess that's not so bad–you can visualize it as bundle of ~4 #2 pencils.
Edit: Still, doubling the length of a skinny cylinder holding volume is increasing the surface area by approximately sqrt(2). More precisely, as [radius divided by length] of the original cylinder goes to 0, the ratio of their surface areas goes to sqrt(2). Which probably justifies the reduction in DR of streamlined ships. Last edited by Michael Thayne; 09-07-2017 at 11:07 AM. |
09-07-2017, 09:47 AM | #17 | ||
Join Date: May 2010
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Re: [Ultra-Tech] [Spaceships] Weapons that are hard or impossible to miniaturize
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09-07-2017, 10:17 AM | #18 | |
Join Date: Jul 2008
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Re: [Ultra-Tech] [Spaceships] Weapons that are hard or impossible to miniaturize
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And, well, sort of. If, like an MBT, your spaceship armor plan cares about protection in one direction above all others, a cylinder with a single massively armored endcap is a pretty good design...
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I don't know any 3e, so there is no chance that I am talking about 3e rules by accident. |
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09-07-2017, 11:10 AM | #19 | |
Join Date: May 2010
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Re: [Ultra-Tech] [Spaceships] Weapons that are hard or impossible to miniaturize
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And that's a good point. I've previously suggested a "tank hull" design feature that double DR from the front and rear while halving it on the top and bottom. I should look more at the SDV hulls in THS 3e to figure out what a simple way to model would look like. |
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09-07-2017, 11:11 AM | #20 |
Join Date: Feb 2005
Location: Berkeley, CA
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Re: [Ultra-Tech] [Spaceships] Weapons that are hard or impossible to miniaturize
This has the side effect that tactics favors multiple firing platforms so you can hit the side armor.
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