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More on JSF Laser System 422

Posted by michael from the huh-huh-fire-huh-huh dept.
An anonymous reader writes "Seems Lockheed Martin has won a contract to equip future versions of the Joint Strike Fighter with a 100-kW laser. Housed in a dome within the aircraft, the laser's turret would emerge for firing [sound familiar?], and the laser itself is spec'ed to achieve airborne and ground kills at a distance of more than six miles. The problem? According to this Aviation Week article, Lockheed Martin has to figure out how to dissipate 900 kilowatts of heat. Maybe the Finnish airforce could value-add to the OEM model." We mentioned this earlier.
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More on JSF Laser System More

More on JSF Laser System

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  • Popcorn anyone? (Score:3, Insightful)

    by Wireless Joe ( 604314 ) on Friday September 27, 2002 @06:56PM (#4347888) Homepage
    Can I get mine with extra butter and popped from 6 miles away, please?

  • sounds more like (Score:5, Interesting)

    by graveyhead ( 210996 ) <fletch@fletchtr[ ]cs.net ['oni' in gap]> on Friday September 27, 2002 @06:57PM (#4347893)
    the plot of Real Genius [imdb.com] than a star trek episode...
  • 900Kw of heat, and only a 100Kw laser? Wow, not to effcient is it?

    I would bet that they could rig up some sort of Athelon style heat sink, the air flow over it at Mach 1 should be able to take care of the heat. That seems the be how much air flow is required in my Dual Athelon system here.

    • Re:Thats a lot of heat! (Score:5, Informative)

      by spike hay ( 534165 ) <blu_ice&violate,me,uk> on Friday September 27, 2002 @07:04PM (#4347918) Homepage
      900Kw of heat, and only a 100Kw laser? Wow, not to effcient is it?

      Very efficient for a laser. Most lasers get less than 1%.
    • 900Kw of heat, and only a 100Kw laser? Wow, not to effcient is it?

      It's more efficient than a the single-digit percentage efficiency of a standard incandescent light bulb.

    • Intentionally radiating 900Kw of heat into the air is *not* a good strategy for a stealth aircraft.

      Cheers
      -b
      • If you read the article, you'll see that the heat will get transferred to the fuel. Although this sounds crazy, apparently there will be enough mass so that the temperature change will be only a few degrees.
    • I would bet that they could rig up some sort of Athelon style heat sink, the air flow over it at Mach 1 should be able to take care of the heat. That seems the be how much air flow is required in my Dual Athelon system here.

      They need a case mod for the JSF. I suggest one of the water-cooled systems; a second non-laser-firing plane can fly alongside with the radiator. Only a few hundred meters of tubing for the water would be needed to connect the two.

      Alternatively, mount a gigantic fishtank on top of the aircraft.

      I don't remember any of the other weird case mods that have been posted here, for which I'm sure all of you are thankful. :-)

    • Thats a lot of heat!

      900 Kw? That's only about 1200 horsepower.

      I wonder if they could dump it into the engine intake air, for a boost? Or just wrap an extra turbopump around a radiator to get an extra couple hundred horses worth of thrust (and a free fan for the radiator) whenever the laser fires.
  • Anyone remember the Uplift Saga by David Brin? In the first book, can't recall the name, they were flying a spaceship through the upper parts of the sun, and they were using a laser to dissipate heat. So....was David Brin talking out of his ass, or is there really a way to put the heat generated into the beam?

    • Anyone remember the Uplift Saga by David Brin? In the first book, can't recall the name, they were flying a spaceship through the upper parts of the sun, and they were using a laser to dissipate heat. So....was David Brin talking out of his ass, or is there really a way to put the heat generated into the beam?

      I know lasers are often used to lower the temperature of small numbers of atoms in order to observe quantum effects, among other things. This is not the same as dissiptating heat, mind you. Heat is a measure of radiation, whereas temperature is a measure of molecular motion. I would imagine that Brin got his vocabulary mixed up.

    • Well, in Sundiver, the book you remember, heat is absorbed and used to generate power for the laser - the key being superefficient power generation, which we don't have today.
    • You can use lasers to lower temperatures, but that's by using the energy of the laser to cancel out the vibrations of the atoms, not by putting energy into the laser beam.
  • This could be a hell of a weapon system, if they can get it to work right. Also, I wonder what the time period is for the 100KW to be transfered to the target? If this is a pulsed laser, that'd be great, but if its a continious laser, I wonder how well it'll really work against a manuvering aircraft. Still, 5 miles up and destroying ground based vehilces would be a nice way to do things.

    • Re:Very Nice if it works (Score:4, Informative)

      by tc ( 93768 ) on Friday September 27, 2002 @07:13PM (#4347945)
      Watts is a measure of power, i.e. energy per unit time. So, to ask how long it takes to deliver 100KW is nonsensical. Did you perhaps mean, how long can this thing fire for continuously, i.e. how much energy can I fire at the target in a burst?
      • Watts is a measure of power, i.e. energy per unit time.

        Oops, good point, been out of school too long, I'm used to hearing laser power in terms of Joules, which necessates the type of question I asked. Sorry, didn't engage brain fully.

        • I'm still wondering how much damage that would do. 100 Kilowatts, isn't that like 67 hairdryers? How much damage can you do with 67 hairdryers? (Mental image from Diamond Age: an army of girls armed with hairdryers marching on the city at the end of the book.)

          Seriuosly, I'm wondering if the laser isn't affected by clouds and stuff, or it can track the target for a while, because I guess I'm not sure what effect this weapon is going to have. I could see it being bad for metal, like a tank, but what will it do to brick or concrete? What does it do when you shine it on someone? Really bad sunburn in like one second? Third degree burns after two?

          Won't the beam be all un-collilmated and shit after passing through six miles of atmospheric effects, or is 100 kW so much that it laughs at minor perturbations?

          At first I was kinda horrified by the prospect of airborne killer lasers, and well I guess I still am. But I'm afraid of a fully-loaded F-18 even without the lasers. Cluster bombs in particular are something I never want to have dropped anywhere near me. Unlike cluster bombs, when the laser turns off, it won't leave behind unexploded little bomblets for the kids to play with.

          And I bet that huge killer lasers are a lot more environmentall friendly than the current nasty chemicals used in conventional weapons.

          Unless they use freon for dissipating that extra 900 KW.

          • Re:Very Nice if it works (Score:5, Informative)

            by JoeRobe ( 207552 ) on Friday September 27, 2002 @09:07PM (#4348320) Homepage
            I work in a laser lab, were the laser we work with (an Argon Ion) puts out a maximum 15 watts of power (of multiple wavelengths of visible light) in a ~5mm diameter beam.

            At 1/2 watt, it will blind you immediately if your eye passes in front of it.

            At 3 watts, it will burn through a piece of paper.

            At 6 watts, it's burning through my sleeve.

            At 8 watts if I accidentally wave my hand through it, it will cause blisters to form several minutes later.

            At 10 watts, our power meter starts smoking and our mirrors begin to get these ugly burn marks on them.

            At 15 watts, it'll burn through an aluminum can.

            This is for a continuous wave laser (one that doesn't pulse). Now you can imagine what 100,000 watts will do:). The question is, seeing as how this must be firing in pulses, what is the pulse length? Minutes? Seconds? Milliseconds?

            I'm also curious what wavelength it is firing at. I didn't notice it in the article (but I definitely could have missed it). Anyway, I hope that helped answer your question. Maybe some other slashdotters out there have worked with more powerful lasers?

            JoeRobe
          • How much damage can you do with 67 hairdryers?

            Depends. Take all the energy dissipated by those hairdryers in, say, 1 second, cram it into a pulse lasting, oh, say, a microsecond, and you're dumping a lot of power. That sort of power will happily break things.

            Or, to put it another way: 100 kilowatts, isn't that like 135 horsepower? How much damage can you do with 135 horsepower? Try driving a Ford Festiva into a bridge abutment at 70 miles per hour, and you'll find out.
          • And I bet that huge killer lasers are a lot more environmentall friendly than the current nasty chemicals used in conventional weapons.


            Huge killer lasers that use a chemical reaction to pump the beam generate some horrifically nasty chemical byproducts. Take a COIL, a chemical oxygen-iodine laser. You don't want to breathe, ingest, or even look too hard at what's leftover when one of those fires.
  • I guess they forgot about the "splash" dammage effet of a "laser". If this device were to hit any sort of reflective material, the potential to permenently blind large ammounts of people is great.
    • guess they forgot about the "splash" dammage effet of a "laser". If this device were to hit any sort of reflective material, the potential to permenently blind large ammounts of people is great.

      Hey, even better. Not only do you take the tank out, you blind the infantry that is near it!

    • Chrome tanks, chrome fatigues, and mirror Cochese shades?

      SWEEET!

      • Very interesting point. What's to keep an enemy from using a reflective material, not much unlike that used in traffic signs, which somehow reflects *most* of the light directly back at the same angle it's coming from?

        How do these signs work anyway? I discovered this once when I was playing with a laser pointer and a stop sign in front of my house. It looked really bright from my perspective if I was the one aiming the pointer, but if someone else did it from another angle, it didn't look much different from shining it on a plain wall.

        • At these levels of power, the reflective material would have to reflect virtually all light in order to be safe. And when I say "virtually all," I mean on the order of 99.999%. I believe a 12 watt laser can cut through sheet aluminum pretty handily, and aluminum is both somewhat reflective and highly heat-conductive. A kilowatt-scale laser should be able to cut through just about anything, shiny or otherwise.
    • With that kinda wattage, I'd image the reflective damage would do more damage than just blinding. You'll probably wind up with a quite crispy coating if you're in the path of any reflected shimmers =)

  • Dissipating the heat into the fuel... (Score:3, Interesting)

    by richard-parker ( 260076 ) on Friday September 27, 2002 @07:10PM (#4347936)

    To dissipate the heat, cooling loops will be employed to take heat from the laser system and transfer it into the aircraft's fuel tank, where it can be burned away.
    ...
    "If you think about the amount of fuel onboard a jet aircraft, if you put all that heat in the fuel, you might raise it by a degree, something on that order," he said.
    Unless, of course, the aircraft has expended 99% of its fuel - in which case the temperature of the remaining 1% of the fuel would raise by 100 degrees. Ouch.

  • Heat (Score:5, Funny)

    by bytesmythe ( 58644 ) <bytesmythe@@@gmail...com> on Friday September 27, 2002 @07:12PM (#4347943)
    Lockheed Martin has to figure out how to dissipate 900 kilowatts of heat

    They can use whatever heatsink comes out for those 4 Ghz Pentiums...

    • No way...too simple. All the fighter pilots should just ask Lockheed to install auto-warming cupholders now. It will help drowsey pilots on those long flights around hostile airspace.
    • Actually, that wouldn't be a bad idea. A high-end PC HSF might have 2 fans - imagine the air cooling you could get at Mach 2!
  • As powerful as a 900Kw laser is, should they mayhap try focusing on making it produce less heat, rather than attempting to simply funnel it away?

    I'm sure they already investigated it, but I'd be looking to more applied material sciences to come up with a cooler-by-design laser, rather than cooler-by-dissipation. Less of a power drain that way too.
    • From the article:
      Lockheed Martin believes that a 100-kilowatt laser is the minimum power level needed to be an effective weapon for a fighter.

      However, "to get 100 kilowatts of light out, you've got to put a megawatt of electrical power in, so somewhere along the way you've got to deal with 900 kilowatts of cooling," Tom Burris, lead for directed energy at Lockheed Martin Aeronautics, told The DAILY. "That's a ton, for a fighter that normally does tens of kilowatts of cooling."

      It's a 100KW laser; that requires 1MW of energy. The energy that didn't go into the laser is lost as waste heat, hence 900KW of heat need to be dissipated. The only way to reduce the amount of heat would be increasing the laser's efficiency, and as other posters have already pointed out, 10% is excellent efficiency for this kind of system.

  • Not on the plane... (Score:4, Funny)

    by SaturnTim ( 445813 ) on Friday September 27, 2002 @07:17PM (#4347972) Homepage

    I didn't want it on the aircraft,
    I wanted them mounted on the sharks!

    All I want are sharks with freakin laser beams on their head!

    --Dr. Evil.

  • I wonder.... (Score:5, Funny)

    by nizo ( 81281 ) on Friday September 27, 2002 @07:20PM (#4347980) Homepage Journal
    if they are gonna put a huge warning sticker on the front of the figher: "Do not stare directly into laser"?
  • ... of how hot this laser could get? I'm sorry, I'm not the guy you can throw kilowatts at and know exactly how powerful (or not so powerful) a laser like that is.

    Don't get me wrong, it sounds cool, but I've yet to hear of a vehicle mounted laser that could do much damage other than filling people's houses with popcorn.
    • Well, a watt is a joule/second.

      A calorie is the amount of energy to raise 1 gram of water by 1 degree Celsius and there are 4.19 Joules in a calorie. Therefore, 100 kilowatts = 100 000 W = 100 000 J/s ~ 25 000 calories/s which means we could raise 25 kg of water by 1 degree in 1 second. Now this would have to depend on the surface area of the target - it could be 2.5 kilograms of water by 10 degrees in a second or .25 kilograms of water by 100 degrees. This is not particularily accurate but it gives you an idea of the power - water is not particularily easy to heat and if this laser could fire for even a few seconds on a fairly small surface area....ZAP!
  • The legendary SR-71 (high altitude mach 3 spyplane) kept the fuel stored at an extremely low temperature in the tanks (sub zero initially I believe), then pumped it through fuel lines running throughout the aircraft. The fuel would absorb the heat from the various internal components of the plane before arriving at the engines.
    • Odd, I seem to recall that the SR-71's fuel tanks also leaked at low temperature. That'd make it a real pain to keep the liquid cooled. Though not outside the realm of posibillity.

      • They did not leak because of the low fuel temperature. They leaked because of loose sealings that had to exist due to the expansion of the materials in high-speed, high-friction flight. The JSF will not experience such heat and likewise will not need accomodations like this.
    • The SR-71 didn't use cryogenic fuel. It used a hydrocarbon fuel not very different from kerosene.

      I didn't realize, however, that it used fuel to cool the toasty bits. I'll read up on that. I'm on a team at school that is looking at using the J58 engine cores from the '71 as the first engine stage for an air-breathing SSTO vehicle. We're going to need to cool our airframe a bit. : )

      • Re:Not the first time fuel has been used to cool (Score:5, Informative)

        by Phanatic1a ( 413374 ) on Friday September 27, 2002 @08:44PM (#4348263)
        It used a hydrocarbon fuel not very different from kerosene.

        Very different from kerosene. Most military jet aircraft run on JP-5 or JP-8, which are essentially aviation kerosenes.

        The SR-71 runs on JP-7. JP-7 is a more viscous fuel with a low vapor pressure and a very high flashpoint. So high, in fact, that the SR-71 can't start its own engines. To light the fires on a Blackbird takes a chemical ignition system, where the ground crew squirts a measure of tetraethylborane into the engines. TEB is actually hypergolic with JP-7, and the resultant explosion starts the engines.

        The airframe heats up to 1000 degrees F in high mach flight, and so it has to be built to fit together nice at the higher temperature. When it's on the ground and cool, it does indeed leak fuel like a sieve. And yes, they do pump fuel from tank to tank in flight to cool hot spots.

        Dear lord, what a plane. 5.2 thrust-to-weight ratio. 3200km/h. 85,000 ft ceiling. 1100 C inlet temperatures. 2000 degree combustion exhaust. Has successfully evaded over 4,000 SAMs.

        Like, wow.
    • The legendary SR-71 (high altitude mach 3 spyplane) kept the fuel stored at an extremely low temperature in the tanks (sub zero initially I believe), then pumped it through fuel lines running throughout the aircraft. The fuel would absorb the heat from the various internal components of the plane before arriving at the engines.

      Not a very safe design it sounds like. One missle or spark could set the whole plane ablaze pretty quick. I guess their strategy was to assume that they could outrun any danger.
      • I guess their strategy was to assume that they could outrun any danger.

        There was no assumption about it; that's specifically what it was designed to do. The SR-72 could, outrun any danger, and probably still could today. When it's going into hostile airspace, it's running flat out at over Mach 3, and at very high altitudes of over 80,000 feet.

        Even if the plane you're trying to intercept it with can go that high, that's a hella difficult intercept geometry. Even for SAMs, which can travel at high Mach numbers, that's a hella difficult intercept geometry.

        Over 4,000 missiles have been fired at SR-71s over the years. Not one SR-71 was ever lost due to enemy fire.

        Assume, my ass. And really, let's face it; if you take a missile hit at Mach 3 and angels 80, the design of your fuel tanks is not going to make a bit of a difference, because the aerodynamic forces are going to rip the plane to shreds faster than you can say "Challenger."

        The fuel wasn't cryogenic, either. STP when it went into the tanks.

  • Focusing the beam (Score:3, Informative)

    by RayBender ( 525745 ) on Friday September 27, 2002 @07:36PM (#4348064) Homepage
    These clowns never mentioned that the "adaptive optics" they want to use to keep the beam focused are very experimental (in this application). I have worked with the stuff, and it is ok for astronomy - but actually focusing a laser in the sort of environment the JSF will be in (low altitude, high-G forces, turbulent flow across the aircraft skin) strikes me as really hard.

    I'd say we should wait and see how the ABL performs before getting rid of the trusty ol' AMRAAM.

  • Lockheed Martin has to figure out how to dissipate 900 kilowatts of heat

    Just a quick proposal here... perhaps it may be easier to dissipate 9,000 hectowatts of heat with current technology. Even better, I think they could probably dig up a cooling fan from a overclockers outlet that'll dissipate 90,000 deciwatts of heat with ease.
  • Housed in a dome within the aircraft, the laser's turret would emerge for firing [sound familiar?]

    You ignorant slut! Those are Phase Cannons, which use an entirely different technology than a laser.

    Enterprise is NOT Austin Powers. They do not use "LASERs"

    That's it! No Xbill for a week, Michael! You must suffer for your non-geekish ways, and suffer you shall!

  • Star Trek? Huh? (Score:3, Funny)

    by smoondog ( 85133 ) on Friday September 27, 2002 @07:39PM (#4348073)
    Housed in a dome within the aircraft, the laser's turret would emerge for firing [sound familiar?]

    I find the suggestion of a Trek parallel humorous. Of course a laser turret that emerges to fire is somehow the visionary genius of a Trek writer. But, I guess whale penises do that too. Oh well...

    -Sean

  • anyone else have images in there head of a joint strike fighter being sizzled with the black spy (insert terrorist of your choice) in a broken down mig one with a mirror hanging off the tail fin grinning in the for ground.
  • Maybe I'm missing something really obvious, but I don't see how it can achieve "airborne and ground kills at a distance of more than six miles" unless the air is clear. Heck, they say they need to do special tricks just to get the beam through the aircraft's own turbulence.

    If the laser is powerful enough I suppose it can evaporate the fog, but... let's see, World War II "FIDO" (Fog, Intense, Dispersal Of) installtions used 75,000 gallons of gasoline. I'm not sure just how long those 75,000 gallons lasted, but I don't think it was very long. Let's say an hour. One gallon of gasoline/hr = 100,000 BTU/hr = 30 kilowatts. So a FIDO installation while in operation might have been putting out about 2000 megawatts.

    On a clear day, you can kill forever?

  • Playing fast and loose with power and energy (Score:3, Informative)

    by HotNeedleOfInquiry ( 598897 ) on Friday September 27, 2002 @07:53PM (#4348133)
    "to get 100 kilowatts of light out, you've got to put a megawatt of electrical power in, so somewhere along the way you've got to deal with 900 kilowatts of cooling," This sentence means nothing to an engineer. Here's why: 900 kilowatts over 1 millisecond is 1/4 of a watthour. A trivial amount of energy to dissipate. Over 1 second, it's 250 watthours, no big deal, but not trivial. Over 1 hour, it's 900 kilowatt hours, a very big deal. Without time, it's just big impressive numbers for the ignorant masses.
  • I would think the simple solution would be to pump the heat directly to the afterburners so that after firing a laser would could be very easily traced back to your plane (just follow the straight line), you could use the burst of speed to flit away.
    • JSF is a stealth fighter. Afterburners are very bad things to use over enemy territory in a stealth jet. I'm sure the JSF is built to have almost no heat signature at all -- lighting off the afterburners would negate any advantage it has in terms of stealth.

  • Beginning of the end of US aerial dominance (Score:3, Insightful)

    by Mittermeyer ( 195358 ) on Friday September 27, 2002 @08:21PM (#4348209) Homepage
    This project is utter foolishness. If we figure out how to operate a 1mW 6.2 mile laser on a fighter, that makes it portable enough to fit on a truck or tracked vehicle. With a greater percentage of a groud vehicle being able to be committed to power systems, a ground-based mobile laser will be ablt to outpower an airborne version, and likely be a LOT cheaper.

    Outranged outgunned outnumbered airplanes are NOT what we want. We are trading decades or our airpower in for a few measly years of SAM and ground strike invulnerability. This direction is NOT smart for us.
    • If we figure out how to operate a 1mW 6.2 mile laser [...]
      First of all, it's a 1MW laser, not a 1mW. I read that as "milli" and did a double take.
      [...] With a greater percentage of a groud vehicle being able to be committed to power systems, a ground-based mobile laser will be ablt to outpower an airborne version, and likely be a LOT cheaper.

      Outranged outgunned outnumbered airplanes are NOT what we want. We are trading decades or our airpower in for a few measly years of SAM and ground strike invulnerability. This direction is NOT smart for us.

      Your argument doesn't make sense. You just mentioned SAMs -- ask yourself, what's the difference between rocket-based weapons and lasers? By your reasoning, ground-based vehicles armed with missiles should be able to annihilate similarly-armed aircraft. Obviously they don't, because the aircraft has the advantages of maneuverability, speed, and stealth.
  • I totally just got a flashback to austin powers there. I don't know why, it just seems apt.
    Dr. evil and his obsession with "LAYSERS" (yes, I did the quote unquote finger thing when I wrote that).
    kinda like in the new one where his son gives him the sharks with lasers on their frickin heads.
    or the laser that he was gonna use to blow up the earth.
    funny shit.
  • Perhaps a tin-foil hat would actually be some use here.

    It'll be amusing when finds that you can beat a frickin big "laser" with a fickin big mirror :)
  • how to dissipate 900 kilowatts of heat

    That's easy. Screw the 100 kilowatts of laser, just nail them with a 900 kilowatts heat ray.

    -

  • Ohohohoh yes... (Score:3, Interesting)

    by silvaran ( 214334 ) on Friday September 27, 2002 @09:36PM (#4348410)
    Star Trek, here we come... Mr Worf, arm phasers!

    I think the best part about a country having powerful weapons is their ability to NOT use them. Keeps evil powers in check (of course, evil is a subjective term, but anyways...). Same with nuclear weapons. Einstein basically told U.S. representatives, "yes, splitting atoms will work, but don't do it. It has disasterous consequences." Well, they didn't exactly listen. But I hope the ability to develop new weapons comes with the mindset to not use them.

    I would prefer to see these laser weapons go from fighter jets to medical surgery. Imagine the medical uses for this. Small, precise cuts, no sterilization necessary.
  • You'd think that we'd learned from our mistakes. When the ABL system [airbornelaser.com] came out the first thing the enemy did was to CHROME all their missiles. Guess someone forgot that lesson...Oh well. Just taxpayer money..

  • A med-laser? What's that, 5 heat per turn?

    The XL engine alone has 10 heat sinks, enough to mount two of those beasts... ; )

    </obligatory MechWarrior reference>

  • intyernational treaty (Score:3, Informative)

    by JDizzy ( 85499 ) on Friday September 27, 2002 @11:18PM (#4348669) Homepage Journal
    Usage of these weapons is actually restricted by international treaty [hrw.org]. The reason is that high intensity light systems could be used to permanently blind the foot soldiers, and that is considered unsportsman like warfare. Sorta like the way nukes are considered unsportsman like too! But lasers, like any other bright light, does't just kill people. They can blind them, and permanently too. That is considered to be off limites. Now melting the armor on a vehicle is fair game, and if you happen to be looking in the laser and manage to not get your skin instantly burned (not likely), but you go blind; your fair game cuz you were sitting on an legitimate target (the armor vehicle). But swooping down on populated areas, and then sweaping the crowded areas with bright lights is bad.

    The treaty was a bit unclear, and unfourtunatly I don't have the deatials, but as I recall it might be offlimites to use the laser to blind enemy pilots too. As in shining the beam inot he cockpit of the enemy jet! I guess it depends ont he situation, and the combat senarios.... but we are realyl treading new ground here!

  • 900kw of heat? (Score:3, Interesting)

    by Perdo ( 151843 ) on Saturday September 28, 2002 @02:54AM (#4349236) Homepage Journal
    On a vehicle that uses heated gas expansion for propulsion (fancy name for a jet), It seems like 900kw of extra heat could be used in place of an afterburner.

    Just find a fluid that does a phase change efficiently between the melting temperature of the laser's mechanism and say just a little hotter than the jet's exaust plume.

    Liquid boron or sulfer ought to do the trick.

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