America closer to battlefield laser weapons

America closer to battlefield laser weapons.

http://www.oaklandtribune.com/cda/article/print/0,1674,82%7E1865%7E1709759,00.html

 

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Currently the really powerfull lasers still are rather large. The challenge is to scale them down to fit a humvee or a soldier, the solid state lasers look very promising...

Meanwhile , I still think that excellent vehicles forheavy giant laser would be large stratospheic balloons the skin coated with the latest gallium/arsenide photovoltaics and hydrogen fuel cells and radar/infrared equipment to become some evil eye in the sky Airships are rather slow, but the sheer altitude will protect them from small firearms and the giant laser would protect it against large firearms / rockets /planes while also being the primary attack beam. The airship would create a really huge denial area where it could see and attack allmost anything that moves, also several airschips could act as relay stations for radardata to make a detailed realtime battlefield map, also relaying communication between troops or how about relaying energy by combining the pulses of two other lasers into one big beam against the really hard targets?

But all the technology of the world is not gonna make up for idiots behind the controls or bad foreign policy....

 

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There are many problems with this weapon. You'll need a very powerful power supply to give the energy needed to make these things useful which means a generator or big batteries which weigh allot. Then you have to be very close to whatever it is your shooting at for they get weaker with distance. They reflect off of mirrored objects and can be reflected right back at you.

 

Yeah, sounds impressive in the lab, and inch of steel being drilled in two seconds, but not much use for the battlefield.

Just try keeping a laser focussed on the same spot on a moving target for two seconds, before a torrent of hot metal is targetted back at you.

So the power needs to increase a hell of a lot, so targetting isn't an issue. And of course, size, so it's a matter of more power, in a smaller space, so a double whammy on energy density of your power supply.

Some day, maybe, but so far, I'm still fan a fast moving lumps of matter.

 

...try shaolin soccer!

 

Sorry for the long post, but this is a topic near and dear to my heart.

HMMWV Avenger is slated for rollout in 2006. That's a normal Humvee with a Deuterium-Fluoride chemical laser on its back, coupled with a short range search and track dual-mode radar for fire control. The primary purpose of HMMWV Avenger will be artillery mitigation. Like how everybody fears for Seoul if the North Koreans decide to pop off a few salvos of their tube artillery? Well, point defense lasers would take care of that nicely. If you recall about a year or so ago, the US Army tested the THEL at the HELSTF in White Sands, N.M. The THEL tracked and destroyed a 155mm artillery shell in mid-flight. The large significance of this is the small size, high speed, and low heat signature of a tube artillery projectile.

Here's the sexy press release picture, one of several:

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Well, the DoD has one part of your theory down, heh. A Blimp For Homeland Security?

This is all very true, and you're pegging every one of the obstacles to laser weapons development. Today's laser technology (with perhaps the exception of the newest chemical combustion lasers) don't lend themselves to easy weaponization.

About the only thing current tech is good for is hitting things that are naturally fragile and sensetive to outside influence. Chief amongst these are artillery shells and ballistic missiles. Both are largely unguided during flight, meaning that even the slightest impingement on their ballistic trajectory can send them careening far enough off target to render them ineffective, and not much additional damage is necessary to make them explode completely.

Additionally, missiles and artillery shells are small and fast. Take, for example, the Russian SS-N-22 Sunburn antiship missile. It flies above Mach 3 and less than 100 feet above the waves. At such a high speed, point defense guns like the CIWS (with a range of roughly two nautical miles) only have about six seconds to engage them before they hit during which they're in the CIWS's engagement envelope. The 14mm subcaliber sabot the CIWS's M61A1 Vulcan cannon fires from its six barrels has a very high muzzle velocity - about 3,800 feet per second. Even so, a Sunburn at two miles will have moved nearly 500 feet during the time from when the CIWS round left the gun barrel and when it arrived at the missile. So the CIWS has to lead the target by quite a bit. This is fine, because that's what the CIWS is designed to do anyway. But.... A ship with a point defense laser like the US Navy has been toying with since the early 1990s has an extreme advantage. The same Sunburn missile will have only moved about 4mm from the time a laser beam leaves its aperture to when it bathes the missile with its wonderful coherent beam of immolation. You don't need to lead a target at all with a laser.

The last large advantage is ammunition supply. The MIRACL and COIL are TRW's and Rockwell's contribution to the US laser weapons effort. Both of them are chemical lasers, meaning they produce laser light by amplifying the light from a flame of a chemical reaction. In the MIRACL (Mid-IR Advanced Chemical Laser) a combination of Deuterium and Fluorine is used, and in the COIL (Chemical Oxygen Iodine Laser), ...you can guess what it uses from the name. Both lasers use a binary chemical mixture for fuel, and the only electricity required is that to run the pumps and scavenging blowers - the lasing cavity looks more like a jet engine than an optical apparatus. For the Airborne Laser, a theater missile defense platform that will achieve interim operational capability in 2005, the COIL and lasing fuel is carried in the 747's cargo bay with the directing optics in a nose-mounted ball turret. Enough fuel for 200+ shots can be carried at once, and refueling takes minutes on the ground. For the HMMWV Avenger and THEL vehicles (about one in the same), fuel will be carried in the back and also be easily replenishable. You couldn't achieve this sort of compactness and flexibility with an electrical laser.

As for this article in particular it's pretty cool stuff, but for now:

For heavy targets like tanks and good heatsinks like the human body, kinetic projectiles will remain the superior form of attack for a long time to come.

 

Just for kicks, do you think it would be possible to use plasma, like from a fusion reaction to do this?

 

Common gas lasers like the Helium-Neon and Argon lasers use an electrically excited plasma to provide the light.

 

Not quite the plasma I was refering to.

 

Yeah, they could. And as Nasor pointed out, they already do. I know that's not the kind of plasma you meant but it's the same at an atomic level so yes, the physics would work. The issue, of course, is practicality. Until we get magnets compact and powerful enough....I'm sure you know the deal.

Anything that produces light can be turned into a lasing medium, provided you fit it into a resonant cavity with tuned mirrors.

Incidentally, the US Army's laser weapons research facility at China Lake has a compact solid state laser that produces 200khz pulses of near-IR at 100 kilowatts. By pulsing, it can drill through an inch of high carbon steel in less than one second. The coolest part? It can fit into a Humvee and run off of battery power, since its average power is still pretty low - low enough to run off of a modified vehicle's electrical system. They're going to put this laser in the F-35 Joint Strike Fighter for point defense against missiles, and perhaps in the AC-130 Spectre gunships for air-to-ground. Hard to believe that this kind of stuff will probably be on the battlefield within ten years.

 

You're leaving out the most important part; lasers need a 'lasing medium' that can undergo a population inversion and be made to emit photons via stimulated emission. Simply putting a light bulb in a mirrored resonant cavity wouldn't be enough to make a laser.

 

Yeah, that's better. I was being a little too simplistic.

 

What happens when the laser hits mirrored reflective anti-laser armor?

 

Reflective coatings would work somewhat as a countermeasure, but with a few important caveats.

1. No surface is 100% reflective. That energy which is not reflected is dissipated by the surface as heat. As heat builds up, the reflectivity of the surface will decrease, and it snowballs from there. Obviously this will increase the time it takes for a laser to inflict damage on a target, but at the power levels we're talking about, it won't be much to speak of. Mirrors for industrial lasers need to be water cooled, in spite of being over 99.5% reflective for this reason.
   
2. For a surface to remain highly reflective, it has to be kept scrupulously clean. I once accidentally destroyed a $500 Germanium mirror for a CO2 laser because I put it in the beam (set at 500 watts at the time) while it had an invisible sheen of oil from my finger on it that I had wiped off with a lens cloth. I hadn't used cleaning solvent though, and the mirror shattered in a fraction of a second. For tanks/aircraft/missiles to be able to reflect enough of a weapons-class laser beam to be impervious, they'd need to be polished to an optical grade and wiped off up to clean-room specs. Not the sort of thing that's practical in combat.
   
3. Surfaces are only reflective to a certain range of wavelengths. For example, the Germanium mirror I talked about above was highly reflective to CO2 laser radiation in the far-IR region at 10.6 microns (visible light centers around .4 microns) was glossy black - completely unreflective to visible light. OTOH, mirrors for a Ruby laser, which outputs radiation at .69 microns (deep red) are standard silver. If you switch the two with their respective lasers, each will shatter immediately. Now, weapons-class lasers like the MIRACL and COIL produce radiation in the near-IR at 1.3 microns. This is because 1.3 microns is the "brightest color" produced by the flame of the Deuterium-Fluoride combustion reaction, so it is the one chosen for amplification. The same lasers could produce a different wavelength with different mirrors tuned for another one of the more prominent lines produced by the DF reaction. So, if an enemy were to armor their vehicles/missiles with a reflective coating, provided they kept it clean and polished, the resonant cavity optics of the lasers could theoretically be changed to amplify a wavelength that they would be vulnerable to. That would take a bit of work though, so if an enemy were competent enough to pull something like this off, I would be tempted to shake their hands.

Just wait until they can build a high powered free electron laser. Any wavelength you want, at the touch of a button - or several at the same time.

 

Cool topic.
Firstly you could, perhaps, keep your reflective armour clean by covering it with, say a plastic film during manufacture. Laser burns through plastic and is then reflected. Could that work?
Also what about enviromental variables? Rain, Snow, dense fog cloud cover ect? Would that bleed energy from your beam?
Dee Cee

 

Plastics are long chain hydrocarbons, so would leave C amongst other things on the surface of the mirror when they burn, and render the mirror less effective. Basically, your coating will dirty up the mirror.

A better solution is a thicker coating deliberately designed to ablate, so when the laser hits it, it expands, to dissipate heat, maybe smokes, to make the beam less coherent. Of course, this is only effective if the laser pulse is fairly long. If the pulse is short and high energy (and from what Stokes Pennwalt is saying things aren't that far off) ther won't be time to dissipate the energy.

 

Also now that I think about it reflective armor is going to be very un-stealthy: radar will reflect perfectly and it will emit IR like a radiator.
How about this: a liquid armor when a laser hits it pierces the standard kinetic armor but between that and the interior chamber would be a liquid layer of high-pressure oil or tar that would squirt out of the lased hole, the laser would have to burn the continues stream of oil instead of the last layers of armor, as it burns the smoke would scatter the beam. Of course such a system would be limited to tank size vehicles, I could see large artillery shells with such a system but it would not be as effective (smoke would be blow away) or as long lasted (would not have much space for pumps and extra anti-laser fluid). It might be better for tanks and infantry to move under cover of IR scattering smoke, but missiles and artillery as offensive weapons will so be history if laser become the next thing. Dam if laser are coming it really going to change the nature of warfare. Missile and artillery will be useless against laser defended enemy, airplanes and satellites will even be endangered, all warfare will have to be done undercover on the ground.

 

Tremendously. The THEL (the joint US-Israeli point defense laser) will have a range of, at the most, about four kilometers. Around sea level the atmosphere is very dense (80% of earth's atmosphere is below 3km) and is nothing but transparent to a few megawatts of near-IR radiation. The atmosphere attenuates perhaps .001% of the optical energy, but that is enough to change its density and thus, refractive index. The beam is then lensed off the target as the atmosphere heats up.

At the HELSTF in White Sands, New Mexico, there are black pock marks on the desert floor where lensing has sent the beam of the THEL prototype tunneling into the earth.

The Airborne Laser (part of theater missile defense) will work around most of the atmosphere's attenuational effects by flying upwards of 15km where the air is very thin and very dry. Lensing will not be much to speak of up there, and its effective range will be in the hundreds of km, provided it has a line of sight to the ballistic missile it's gunning for.

First, good point about reflective armor and radar cross section.

Second, your idea has been considered among others. In the 1980s, when the American SDI effort was in full swing (and the USSR was also investigating directed energy weapons), concepts for laser armor were developed. The variant that most closely resembles yours was an ablative coating that would combust into a plasma when struck by a laser beam, thus scattering it before it could strike the foundational fuselage of the missile or aircraft. Not only would this be cheap to implement, but it would not compromise radar or IR stealth because it would be a very thin veneer of material. Principally the same as your idea, but much simpler to implement.

 

I diagree. There nature will certainly change, but a laser is incapable of indirect fire. You can't shoot it through a hill. Most likely the change will be to larger numbers of smaller munitions, to saturate defenses, and methods of thwarting the tracking systems the lasers rely upon. Many armies will discard some forms, but tube and rocket artillery will stay for a long time to come.