Imagining realistic energy weapons

[Tamren]

How much of a muzzle flash do lasers usually have? Beam weapons in general are usually depicted with a cone shaped "flash" emitting from the barrel where the emerging beam inexplicably gets thicker momentarily. Is this just artistic license or does it actually happen? For light to spill out in a "bloom" effect a laser emitter would have to have a lot of unfocused light that doesn't join the beam. So that would probably indicate a poorly designed system.

Most of the examples I can find online are pictures of high powered laser pointers. And its hard to tell if its a characteristic of the beam or something to do with the camera used to take the picture. The mortar point defence laser linked earlier certainly doesn't have one. (visible to the naked eye at least).

[Aygar]

How much of a muzzle flash do lasers usually have? Beam weapons in general are usually depicted with a cone shaped "flash" emitting from the barrel where the emerging beam inexplicably gets thicker momentarily.

A laser in a average enviroment will not have a gun like muzzle flash. If the there are particulates in the air these will cause some backscatter but this will not be muzzle flash like. If the beam is powerful enough then as the beam gets closer to its focal point it may start ionizing the air around it which will be visible but that would not be near the emitter.

--Aygar

[Aygar]

Tamren

See also
http://www.projectrho.com/rocket/sidear ... php#Lasers
and
http://panoptesv.com/SciFi/LaserDeathRay/DeathRay.html

These websites have good information on the behavior of lasers

[osmium]

@ anti-carrot

Do you know what happens when a flywheel fails? I would not call it "not too dangerous" Either the flywheel gets loose, you waste a lot of weight containing it in the first place, or you generate a ton of heat as all of that stored energy (as well as the energy you spent getting the wheel up to speed) is converted to heat. A lot of the new carbon fiber etc high strength materials flywheels are not these miraculous energy storage technology, they have advantages and disadvantages. The difficulty in any energy storage method is getting the energy back into the form you desire, some methods have better (others worse) conversion back to the form of energy you want.

Chemical lasers are nice because the direct byproduct you're looking for is generated and you can just dump the spent reactants (getting rid of the waste heat generated). Batteries are a natural, but with fly wheels or gravitational potential storage systems (towers full of weights and pulleys) you've gotta get that mechanical potential back to something you can use to drive a laser or something. They're certainly great for any mechanical system, but you'd really need to look at the numbers for the specific energy weapon in question to see how they actually stack up vs batteries because it's not just energy storage density, but more like usable energy density because it you lose 50% of that stored energy in conversion...

-O

[Siber]

I recall hearing about flywheel storage where the flywheel is a very long tightly wound ribbon, so when it fails it shreds itself and is relatively easy to contain.[citation needed] I suppose that'd cause a lot of waste heat, but any man portable weapon system could be dropped pretty easily. Seems like the conversion from spinning things to electrical power is something we've rather refined, in every power turbine we've ever built, too...

[Mjolnir]

The ribbon version Siber mentioned and other composite flywheels disintegrate into hot particles rather than producing high-momentum shrapnel. With modern low-rotor-mass very-high-RPM flywheels, the big problem with a failure is dealing with the angular momentum (which can be done using two counterrotating flywheels arranged so that failure of just one is unlikely), and getting them in a usefully sized package. A portable version would need gimbaling so precession forces aren't a problem, which adds to the bulk. In any case, anything capable of releasing large amounts of stored energy in a short pulse on demand is potentially going to do so when sufficiently mistreated...even chemical-propellant bullets.

Flywheels have major advantages for energy weapons, though: high energy density, high efficiency, high charge rate, and given the right design, very high discharge rate. A variation known as a compulsator is used in railguns and other applications needing high energy pulses. Batteries just can't achieve the needed power density and have high losses, and capacitors have low energy density (which indirectly limits the power density at large energies, due to the physical size of the capacitors and the lengths of connecting conductors). For stationary and vehicle-mounted applications, they're a pretty obvious choice.

[Voitan]

http://www.wired.com/dangerroom/2011/02 ... -a-record/

Currently, the free-electron laser project produces the most-powerful beam in the world, able to cut through 20 feet of steel per second. If it gets up to its ultimate goal, of generating a megawatt’s worth of laser power, it’ll be able to burn through 2,000 feet of steel per second. Just add electrons.

We will defeat our enemies by drilling through the planet to hit em on the otherside of the world. Clearly.

[Imbrooge]

Wouldn't the size of a beam weapon weilded by a person be, at the minimum, the size of an antipersonal weapon (like an M-60) or am I being too generous and it would have to be bigger?

I don't really know much about beam weapons but thats just what i'm extrapolating based on what i've skimmed through this thread and would like to confirm it. Presumibly the powersource is ambiguous but is definantly the main reason why I assume it would be so big for something a person would weild.

[Karst45]

We will defeat our enemies by drilling through the planet to hit em on the otherside of the world. Clearly.

i wonder what would happen if you were to drill through the planet with a laser. Would it only melt the rock and stop when it hit the magma? Would it continue to the core and be stopped here or would it continue all the way to the other side. I also wonder what problem that could cause for each situation.

[osmium]

It's just a matter of energy output. What would actually happen would depend heavily on the makeup of the planet and how quickly you can put energy into the target. If it just makes the surface molten and allows said liquid to flow back into the path of the beam you'd have to melt the whole planet. I'm not sure you can physically generate enough power to actually punch through a planet, asteroid sure, big asteroid maybe. You'd be much much better off spending that energy accelerating a 2km wide asteroid at said planet and letting that impact glass the surface of much of the planet and cause the sun to be blocked by the resulting dust storm.

-O

[discord]

and with sufficient velocity would crack the mantle of a tectonically active planet, which would be all kinds of bad....

[bunnyboy]

If you try drill through planet with laser, this will happen.

First laser will turn the air into plasma like big straith lightning. When the laser hit on the surface, earth/stone/existing materia turns to gas, expanding explosively. The hot gas get on way the laser. When the hole goes deeper, there are more plasma on way, which will melt the edge of hole. Also when deeper, to hole will turns to plasmageysir, when high pressure of hot gas try come out of hole.


But if you wan't to continue, you will heat the atmosphere until there are no life on planet, then melt the continent, then melt the planet, then create small star.
And if you still continue "drilling" it will only blow away matter until the gravitation is weak enough to have a hole on to cloud.

[Imbrooge]

2bunnyboy: That is overkill.

In general I realised you could make a laser look like a typical camera, or a flashlight. I am uneasy around cameras enough as it is, the idea that some guy asking to take your picture could actually be pointing a deadly weapon at you and you'd be none the wiser is a whole new can of worms to me.

Even a big flashlight but thats probably more on the remain inconspicious until you reach your target kind of thing.

[bunnyboy]

2bunnyboy: That is overkill.

Yes it is. But any weaker laser makes only a "lava pot" and keeps it steaming.
So no hole through earth. It could work with potato shaped asteroids, when gravity is weak enough to squirt melted & evaporated materia away (in your direction).

In general I realised you could make a laser look like a typical camera, or a flashlight. I am uneasy around cameras enough as it is, the idea that some guy asking to take your picture could actually be pointing a deadly weapon at you and you'd be none the wiser is a whole new can of worms to me.

You don't like this.

[AviLam]

2bunnyboy: That is overkill.

In general I realised you could make a laser look like a typical camera, or a flashlight. I am uneasy around cameras enough as it is, the idea that some guy asking to take your picture could actually be pointing a deadly weapon at you and you'd be none the wiser is a whole new can of worms to me.

Even a big flashlight but thats probably more on the remain inconspicious until you reach your target kind of thing.

Yaap it is. But any gradual laser system device makes only a "lava pot" and keeps it very hot.
So no starting through globe. It could execute with spud established asteroids, when intensity is inadequate enough to implement demolished & vanished materia away.

[sunphoenix]

Wouldn't 'said' laser beam have to be several million degrees centigrade to have that effect? It would be more of a plasma beam then wouldn't it? Since photons... from a certain theory of their nature, have a mass {miniscule as it is}... isn't there a maximum beam density for a given laser bore size?

I would think only a FEL {free electron laser} could attain such beam intensity as I can think of no such material lens that could sustain such temperatures?

[Well unless your talking 'Doc' E.E. Smith Solid Neutronium lenses harvested from the cores of stars... "Love Ya 'Doc'!"]