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Power Science

The Texas Petawatt Laser 174

Posted by kdawson
from the you-can-pet-a-dog-or-you-can-pet-a-cat dept.
Roland Piquepaille notes the hype surrounding what the University of Texas at Austin is calling the world's most powerful laser. During a tenth of a femtosecond this laser is 2,000 times more powerful than all the power plants in the US, and is brighter than sunlight on the surface of the Sun. On his own blog Roland points out that UT's is not the first petawatt laser; that distinction belongs to a system installed at Lawrence Livermore National Laboratory in 1996.
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The Texas Petawatt Laser

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  • by dj_tla (1048764) * <trbekolay&shaw,ca> on Wednesday April 09, 2008 @05:35AM (#23010580) Homepage Journal
    Will this laser have to be attached to significantly more powerful sharks?
    • by Icarium (1109647) on Wednesday April 09, 2008 @05:47AM (#23010636)
      Wouldn't firing this laser underwater make the water uncomfortably hot? Please people, think of the sharks!
      • Re: (Score:3, Interesting)

        by Brian Gordon (987471)
        Wouldn't firing this laser anywhere causally connected with the known universe make earth's water uncomfortably hot? Where do they get the power to run this thing anyway? Do they just jack into all of the power plants in the US for 200 femtoseconds and then release it all in a tenth of a femtosecond? And how does it make sense to refer to the generating capacity of all the power plants the US in terms of energy? There are no times, femtosecond or not, involved, watts are rates of energy consumption.
        • by odourpreventer (898853) on Wednesday April 09, 2008 @07:08AM (#23010932)

          Where do they get the power to run this thing anyway?

          In case this was a serious question: Giant capacitors, connected in parallel.

        • by yoavi (868428) on Wednesday April 09, 2008 @07:34AM (#23011052)
          This is not accurate. Watts are indeed rates of energy consumption, that is, the amount of energy consumed per unit time (Watt stands for Joule per second). Now, if we squeeze 100 Joules in into 10^-13 of a second, then the *instantaneous* power during those 100 femtoseconds (and yes, the story has got it wrong, it's a tenth of a picosecond, not femtosecond, which makes a hundred femtoseconds) is one petawatt. The average power, assuming we operate at 0.1Hz (which I think will be the laser's repetition rate) is only 10 Watts.

          This also answers the "heating" problem. These lasers carry a relatively small amount of energy, and produce very little heat. However, the electric field that is produced when the beam is focused is huge, and many interesting phenomena can be studied with such a laser.

          Btw, for the same reason, this type of laser is completely useless as a weapon. In order to cause any real damage one has to deposit energy into the substance that is to be damaged, and again, these laser pulses carry a relatively small amount of energy.
          • by garett_spencley (193892) on Wednesday April 09, 2008 @08:00AM (#23011184) Journal
            "Btw, for the same reason, this type of laser is completely useless as a weapon."

            Thanks. Another slashdotter crushes another one of my hopes and dreams. Jerk :(
          • by s_p_oneil (795792)
            10 Watts? So this thing is approximately twice as powerful as one of those 5W key-chain laser pointers? That's good to know. ;-)
            • Nope. The key ring laser pointers are 1mW to 5mW so this thing is 2000 to 10000 times the average power. A 10W laser is very good at setting fire to things but won't drill a hole through your still twitching body.
              • by s_p_oneil (795792)
                It was meant to be a joke, but you're right, I messed it up. ;-) If we're being serious though, we also need to account for the fact that the keychain lasers use 1-5mW in a full second, not in 100 femtoseconds, so you would need to scale that number up by several orders of magnitude.
              • 10W lasers are frequently used for engraving in metals and will, if left on long enough burn a hole through steel. While it may take a while, and your body will no longer be twitching, it can and will eventually burn a hole through a human body. The grandparent of your post is wrong about the "heat thing" is also wrong. You have to use the instantaneous power. While the explosive power of firecrackers exploded 1 per second is small, one firecracker explosion is enough to do serious harm to a finger. If any
          • by ultramk (470198)
            Well if my arithmetic is right, this laser would have the same total energy output as a 100-watt laser with a 1-second pulse (or for that matter, a 10-watt laser with a 10-second pulse.)

            So yes, a lot of energy, but not a HUGE amount.
          • Back in the 1970s, when lasers were shiny "new" tech, they would demonstrate them by burning holes in razor blades. This prompted the "Gilette" [wikipedia.org] as a unit of measure for lasers, ie how many razor blades could the laser burn through per pulse. I say it's time to revive this measure.

            So the question arises, is the power delivered to the razor blade be enought to burn a hole through it, or will the shortness of the pulse mean that there's not enough time to do anything but vapourize a few of the surface atom
        • by jiriw (444695)

          Where do they get the power to run this thing anyway?

          Thats where batteries are for... probably a huge array. Or capacitors, or a spinning object storing a huge load of kinetic energy or any other form of energy storage. It's the same way as KEMA (an electronics testing and certification institute I live near) stores it's energy for huge lightning bolts and power overloads they use to test kilovolt transformers, massive power breakers and other high voltage equipment.
          They could store the energy for those 200 femtoseconds. Notice it's only 200 femtoseconds ...

        • by The Bender (801382) on Wednesday April 09, 2008 @07:51AM (#23011132) Homepage
          Obviously the energy is built up over the period between pulses. And since the repetition rate is only 1 shot per HOUR, the average power output is only 0.1 W [calctool.org]!

          That wouldn't even put a dent in my electricity bill.

          Yes I know, I know...
        • And how does it make sense to refer to the generating capacity of all the power plants the US in terms of energy? There are no times, femtosecond or not, involved, watts are rates of energy consumption.

          And by integrating that power over a femtosecond, calculus tells me the result is energy. ;)

          Over the duration of the 200 femtosecond pulse, it's perfectly reasonable to compare either the average power or total energy released to any other energy source, whether it be terrestrial power generation or the sun.

        • They use a ZPM to power it.
      • by Tribbin (565963) on Wednesday April 09, 2008 @07:21AM (#23010982) Homepage
        It will look a little like this:

        http://upload.wikimedia.org/wikipedia/en/d/d3/BFG9000doom2.jpg [wikimedia.org]
        • by Biff Stu (654099)
          The parent comment is modded "funny," but it could equally be modded "informative." When an intense femtosecond pulse is focused into many materials, including water, nonlinear effects will lead to fillamentation and continuum generation. Here [univ-lyon1.fr] are some pictures from lasers with roughly an order of magnitude less power focussed in air.
        • by Biff Stu (654099)

          The parent comment is modded "funny," but it could equally be modded "informative." When an intense femtosecond pulse is focused into many materials, including water, nonlinear effects will lead to fillamentation and continuum generation. Here [univ-lyon1.fr] are some pictures from lasers with roughly an order of magnitude less power focused in air.

          (I corrected a link. Please mod my previous comment down)
      • uh hello, sky/space sharks?
    • by walt-sjc (145127) on Wednesday April 09, 2008 @07:06AM (#23010924)
      Bah - who needs sharks... They will just install them in military jets for when they need a LOT of popcorn...

      "Kent, this is Jesus.... And stop playing with yourself..."
    • by DJStealth (103231)
      You guys beat me to the post about sharks; but when I opened up the page after reading it in RSS, I had a little laugh at the fact that "Sharks" was one of the keyword 'meta-tags' underneath the summary: "power, science, laser, starwars, sharks (tagging beta)"
  • Pish. (Score:3, Funny)

    by AndGodSed (968378) on Wednesday April 09, 2008 @05:39AM (#23010600) Homepage Journal
    I am holding out for Laser Eye Implants.

    (Just don't go glaring at yourself in the mirror...)
    • by hashax (1190057)
      don't, its not good for geeks. if ever in your lifetime a girl likes you, you'll fry her with your intense gaze.
      • by symes (835608)

        don't, its not good for geeks. if ever in your lifetime a girl likes you, you'll fry her with your intense gaze.
        lol! Now I definitely want laser implants - but not for the ability to light candles on romantic evenings with a bat of an eyelid. It's too late for that. I want to fry the mother-in-law!
      • Re: (Score:3, Funny)

        by Anonymous Coward
        It's all good, so long as you remember to shout "BEHOLD! OPTIC BLAST!" before doing it.
      • by EdIII (1114411) *
        One less restraining order I have to deal with. Win-Win.
    • by Walruzoar (514362)
      Well I'm holding out for a handheld laser pointer version, in green of course.
      Will if come with a heavy duty mains lead, or a BIG box of AA cells?
    • Re:Pish. (Score:4, Funny)

      by l1gunman (463233) on Wednesday April 09, 2008 @08:02AM (#23011196)
      WARNING: Do not look directly into laser with remaining eye.
    • <Oglethorpe>
      What do you know of fire? You prance around like you have laser eyes!
      </Oglethorpe>
    • by tinkwink (723486)
      If looks could kill
  • Sorry boys (Score:5, Funny)

    by martin-boundary (547041) on Wednesday April 09, 2008 @05:46AM (#23010632)
    It'll never work. There's just no peta tonne shark to put it on.
  • link to project page (Score:5, Informative)

    by dermond (33903) on Wednesday April 09, 2008 @05:52AM (#23010658)
  • But... (Score:5, Funny)

    by Rix (54095) on Wednesday April 09, 2008 @06:00AM (#23010688)
    Can it levitate a squirrel?
    • by EdIII (1114411) *
      If you strapped on a laser propulsion getup onto his nutsack. That is not that far fetched either. Have you seen a squirrel's nuts?

      Of course that would not be "levitating" as much as it would be "rocketing off into space" at a fantastically high rate of speed.

      That would be fine with me as I have wrote plenty of blogs on the impending apocalypse where the squirrels will make us all their slaves. Everybody says I'm nuts... but you just wait...
  • During a tenth of a femtosecond this laser is ... brighter than sunlight on the surface of the Sun That is 10 to the power of -16 of a second. Such comparisons are ridiculous because even I can say my torch is brighter than the sunlight on the surface of the sun for 1 gazillionth of a second. :P
    • Re:Time duration? (Score:4, Insightful)

      by famebait (450028) on Wednesday April 09, 2008 @06:19AM (#23010748)
      even I can say my torch is brighter than the sunlight on the surface of the sun for 1 gazillionth of a second.

      You could say it, but it wouldn't be true.
    • by ettlz (639203)
      And some of us would rather our torches didn't explode.
    • Re:Time duration? (Score:5, Informative)

      by MLCT (1148749) on Wednesday April 09, 2008 @08:27AM (#23011370)
      They aren't ridiculous - and you are ill informed to say that they are. Average power vs. peak power. Those two variables are highly relevent for a pulsed laser. Your "torch" isn't even pulsed.

      A lot of ground breaking research is undertaken *utilising* the ability to deliver very short very high energy pulses - for doing that you can deliver a huge amount of energy in a very tiny amount of time - then observe what happens. Indeed a lot of the very high energy regions cannot be accessed with anything but ultrafast pulsed systems, as CW setups would just destroy themselves (and even using UF systems chirping "tricks" are used to reduce peak powers until the final moment to ensure the optics aren't burnt out).

      See http://en.wikipedia.org/wiki/Chirped_pulse_amplification [wikipedia.org]
    • by Fizzl (209397)
      Roland has always been good at making mundane shit sound exciting.
      I always got angry when I got lured into his blog by fancy summary, because there is never any substance to his fantastic tales.
  • FTFA: "They will create mini-supernovas."

    the Fools! the Fools! what could possibly go wrong? Actually I'm not so worried about a mini supernova as I am a mini black hole, because I don't see a mini supervova as possibly self sustaining (might take out a few scientists though - there's always plenty more), whilst a mini black whole near a large mass might last long enough to eat us all. Still, a better way to go then the grey goo.
    • by Hojima (1228978)
      You're joking right? I hope that you're aware that we've been creating black holes and other "mini cosmic catastrophes" with particle accelerators for years now. Many crazy scientists (or just overly concerned) have been worried about such things while failing to realize that cosmic rays (which have been colliding for eons) should theoretically produce them since they are based on the same principles. There are even odd super particles that have odd quark configurations that are supposed to convert all mat
      • by Poorcku (831174)
        micro-black holes already created? when? For all i know only LHC will have this kind of power. And i am too a little worried :) - you know, because the Hawking radiation has not been proven yet. If it doesn't exist, we are screwed :)
    • Re: (Score:2, Insightful)

      by Digestromath (1190577)
      You can have mini-black holes, but you can't really have mini-novae or mini-supernovae (mini-super would be a contradiction anyways right?).

      However, your right be concerned about the potential bouts of uncontrollable fusion/fission and thier scientist vaporizing shockwaves.

      The mini black holes aren't a worry. It's when they become large enough to devour scientists, and thier space/time warping event horizons encroach on your personal boundaries, then you should worry.

      Grey goo? Seriously, you're a huma

    • because I don't see a mini supervova as possibly self sustaining

      And if it was self-sustaining, we could probably find a way to harness all that power to run my really big TV.

  • the laser elevator may become true!

    http://blag.xkcd.com/2008/02/15/the-laser-elevator/ [xkcd.com]

    let's lift some squirrels :)
  • Uses? (Score:3, Funny)

    by sjs132 (631745) on Wednesday April 09, 2008 @06:39AM (#23010814) Homepage Journal
    Am I the only one thinking about "Real Genius"? http://www.imdb.com/title/tt0089886/ [imdb.com]

    Lets get ready to cook some popcorn!
  • I am the greatest lover that ever lived.

    But seriously,I have been electrocuted by 20,000V at significant current several times. But only for a few hundred nanoseconds at a time. Sparks plugs rock.
  • Wrong (Score:1, Offtopic)

    by Poromenos1 (830658)
    The duration of the laser is a gross underestimation, it's nowhere near that short. In reality, it's about 100 attoseconds long, and we all know 100 > 0.1...
  • How do I RepRap one of those?
  • by Ancient_Hacker (751168) on Wednesday April 09, 2008 @07:00AM (#23010906)
    A petawatt is only 10^15 watts.

    Our Sun puts out about 4 x 10^24 watts, continuously, for billions of years.

    So this laser is only putting out about one four-billionth of the Sun, and only for a very split second.

    It's also very misleading if they intended to compare brightness per unit area. Even a cheap laser pointer is brighter than the surface of the Sun.

    • To be fair, a 5mW laser point would need to be focused to a diameter of ~10 microns [calctool.org] to reach the sun's surface intensity of ~6kW/cm^2.
      And a cheap laser pointer can't be focused to that size.

      But of course you're right. They're just going for the unwashed public wow factor.
    • by Swampash (1131503) on Wednesday April 09, 2008 @08:46AM (#23011540)
      I would be happier if they expressed the power of this laser in the recognized units of "Libraries of Congress" and "football fields".
  • The pulse length is ~100 fs (0.1 ps), not 0.1 fs. 100 fs is already about as short as laser pulses can get - and 0.1 fs is much shorter than the length of a single electromagnetic wave.
  • Now to put it on a F***ing sharks heads [youtube.com]
  • by justkeeper (1139245) on Wednesday April 09, 2008 @07:23AM (#23010996)
    One femtoseocnd is 10 to the power of -15 of a second,NOT one trillionth of a second.Thus the pulse duration should be 100 fs,which is realistic.State of the art technology can't yet produce high power sub-femtosecond(i.e attosecond) pulses ,due to low conversion efficiency of energy concentrated on the low-frequency spectrum to the high-frequency spectrum using currently available methods(for an attosecond pulse a Fourier Transform will show that you have mostly X-ray frequency components in the frequency spectrum). Discaimer:I'm a Ph.D student working on high-power laser systems.
  • when I read the title I thought it was about a slasher movie
  • by djtachyon (975314) on Wednesday April 09, 2008 @07:32AM (#23011044) Homepage Journal
    University of Rochester is building a petawatt laser of capable of picosecond pulse lengths. http://omegaep.lle.rochester.edu/ [rochester.edu]
  • This is what, "superlaser" nuber four in the last couple months. Always with a firing time down in the femptoseconds or something like that.

    New rule. You cannot call it "world's most powerful laser" until you understand the definition of power . I don't care if you ARE dumping jiggawats into it, if the time period is dividing it by a trillion to come up with the power which ends up somewhere around a AA battery, I don't need to hear about it.
    • You cannot call it "world's most powerful laser" until you understand the definition of power . I don't care if you ARE dumping jiggawats into it, if the time period is dividing it by a trillion to come up with the power which ends up somewhere around a AA battery
      I love the smell of irony in the morning...
    • I believe the other reply to your comment was regarding the irony of you discussing power without understanding the definition of power. Power is an instantaneous measurement, what you are comparing is energy (Power x Time) or AVERAGE power (Power x Duty Factor). I haven't RTFA, but I will believe an earlier post which said the AVERAGE power is about 10 Watts. A "AA" battery delivering 10 Watts of power could do so for ~ 13 minutes (assuming 1.5 V, 1500 mAh); however, this assumes a AA battery is capable
  • I guess this is time to repost that story about the billion-watt light bulb.

    http://www.mit.edu/~jcb/humor/billion-watt-light-bulb [mit.edu]
  • by cnosh (1073210) on Wednesday April 09, 2008 @09:42AM (#23012068)
    You have to put this in perspective. They may have made a laser with highest peak intensities but it's nowhere near the most energetic laser out there. According to their press release their pulses have 150 J of energy. Compare this to the National Ignition Facility at Lawrence Livermore laser, which will produce 1.8 MJ per shot when it is completed next year, or to the laser at the University of Rochester, which will produce several kJ. Though not yet finished, both these lasers have already demonstrated many kJ of energies.
  • by Animats (122034) on Wednesday April 09, 2008 @11:01AM (#23013028) Homepage

    More Roland the Plogger blogspam, driving traffic to his useless ad-laden blog. To get around the block on links to his own site, he's now submitting links disguised via "tinyurl".

    Slashdot covered this laser weeks ago.

    • by Arcturax (454188)
      No kidding, I saw that too.

      Slashdot editors! Wake up and quit posting this WALKING SACK OF PLAGERISM!
  • by SocietyoftheFist (316444) * on Wednesday April 09, 2008 @11:04AM (#23013072)
    They have a freshman wonder kid and a graduating senior working together on breakthrough laser designs.
  • your new Texan Petawatt Laser Overlords.
  • That's approximately one sextillion photons per firing.
  • When I glanced over the summary, I thought that said a petawatt taser.

    Thought to myself...ouch.
  • That diagram looks a little like something I scribbled when I was 2. I was genius then too. ;-)

    Is there anything that explains it?

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