Hard Light Productions Forums
Off-Topic Discussion => General Discussion => Topic started by: headdie on August 18, 2015, 02:14:08 pm
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http://www.iflscience.com/technology/world-s-most-powerful-laser-2000-trillion-watts-what-s-it
Osaka University in Japan, where the Laser for Fast Ignition Experiments (LFEX) has been boosted to produce a beam with a peak power of 2,000 trillion watts – two petawatts – for an incredibly short duration, approximately a trillionth of a second or one picosecond.
The mind boggles at the scales big and small
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Looks like Japan is looking to build a BAUVA*XBR-M-79-07G for next years robot duel :P
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The mega-particle beam is real.
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and small
For reference, in one picosecond light will have only traveled about a third of a millimeter.
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Isn't the energy of a 2,000 trillion Watt laser fired for a trillionth of a second more easily expressed as "2,000 Joules"?
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While not incorrect, that would be missing the important point of the rate at which it delivered the energy.
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I can
run walk at one millionth of five million miles an hour!!!!
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While not incorrect, that would be missing the important point of the rate at which it delivered the energy.
So say it delivered 2 Kilojoules in the span of a picosecond, which is both impressive and more helpful than talking about 2 petawatts multiplied by a picosecond.
I can run walk at one millionth of five million miles an hour!!!!
Basically this.
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I honestly think they're trying to dumb it down for folks who didn't pay attention to their science classes. Or at least I hope they are. :nervous:
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While I appreciate the jaded science-nerd sarcasm as much as the next geek, you guys are seriously missing the point here. As one who worked with lasers pretty closely, the wattage of a laser is pretty much THE thing. I can deliver 2000 joules of energy with a weak laser over a period of a several seconds, and it isn't going to cut anything at all. Might heat it up a bit, but that's all. 2000 joules in less than a second? Now you are talking about the kind of power that might cut through metal. 2000 joules in a picosecond? Now you are talking about cramming enough energy into a small enough space and time that you may be able to incite fusion. Maybe for a very short period of time, but if fusion is the goal, the reaction is very unstable anyway, so a series of very short bursts on repeat is a potentially viable approach to a problem that has proven nearly impossible to perform in steady-state continuous operation.
My $0.03. (Adjusted for inflation)
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As an Engineer who hasn't played with lasers enough, I apologize. :banghead:
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No need to apologize! Just sit back for a minute, contemplate the possibilities, and revel in the AWESOME!!
Lasers are cool. Pew pew.
[tangent] One of my favorite guilty pleasures back when I was working in the laser lab was to take out business cards and slide them into the beam dump for a couple seconds. That needs some explanation. My work involved laser induced fluorescence spectroscopy as a way to monitor conditions in a low-pressure flame reactor. We used a dye laser that could be persuaded to emit at different wavelengths in UV to probe the flame temperature and reactants. The details don't matter. What's important is that we needed a Nd:YAG laser to "pump" the dye laser. The YAG laser was a beast! It's primary beam lases at 1064 nm (infrared). I can't remember the wattage of the beam, but it was pulsing at I think 10 Hz. So you got about 10 hits for every second you left something in the beam.
We didn't need the 1064 nm beam. We needed a harmonic in the UV to pump the dye laser (something of high enough frequency to cause the dye to fluoresce). So, we took the 1064 nm beam and ran it through 2 frequency doubler crystals, filtered out most of the 1064 nm and 532 nm and sent them to the beam dump (basically a non-reflecting enclosed box that was thoroughly opaque at those frequencies, but with high thermal conductivity so it didn't overheat). So, all that trouble to make a 355 nm beam, and the left-overs get sent to the beam dump. Heh-heh.
Well, what happens when you stick a business card in that beam dump is pure unadulterated awesome. Where the beam hits, the card explodes. Doesn't burn, explodes. If you leave it in there LONG enough, the remnants may start to burn. See, there is enough moisture in business card paper that when that beam hits, it flashes to steam so fast it cannot get out of the paper fast enough. The steam is superheated and tries to expand. It can't because it is trapped, so it's pressure increases. Paper fiber is a rather poor pressure vessel, so the paper explodes. Once the moisture is gone, then it starts to burn.
And then all of the dust you just created gets all over your optics and the laser efficiency starts to mysteriously drop and your research advisor starts asking probing questions about any unusual activity in the lab over the last few days. Funny as hell though! [/tangent]
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All I can say is :yes:
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While I appreciate the jaded science-nerd sarcasm as much as the next geek, you guys are seriously missing the point here. As one who worked with lasers pretty closely, the wattage of a laser is pretty much THE thing. I can deliver 2000 joules of energy with a weak laser over a period of a several seconds, and it isn't going to cut anything at all. Might heat it up a bit, but that's all. 2000 joules in less than a second? Now you are talking about the kind of power that might cut through metal. 2000 joules in a picosecond? Now you are talking about cramming enough energy into a small enough space and time that you may be able to incite fusion. Maybe for a very short period of time, but if fusion is the goal, the reaction is very unstable anyway, so a series of very short bursts on repeat is a potentially viable approach to a problem that has proven nearly impossible to perform in steady-state continuous operation.
This is awesome. You just made my day.
My $0.03. (Adjusted for inflation)
This is also awesome. You just made my both mine and my wife's day. :lol: (I didn't tell her about the laser... maybe when the kiddos aren't demanding all of her attention).
EDIT:
[tangent] One of my favorite guilty pleasures back when I was working in the laser lab was to take out business cards and slide them into the beam dump for a couple seconds. That needs some explanation. My work involved laser induced fluorescence spectroscopy as a way to monitor conditions in a low-pressure flame reactor. We used a dye laser that could be persuaded to emit at different wavelengths in UV to probe the flame temperature and reactants. The details don't matter. What's important is that we needed a Nd:YAG laser to "pump" the dye laser. The YAG laser was a beast! It's primary beam lases at 1064 nm (infrared). I can't remember the wattage of the beam, but it was pulsing at I think 10 Hz. So you got about 10 hits for every second you left something in the beam.
We didn't need the 1064 nm beam. We needed a harmonic in the UV to pump the dye laser (something of high enough frequency to cause the dye to fluoresce). So, we took the 1064 nm beam and ran it through 2 frequency doubler crystals, filtered out most of the 1064 nm and 532 nm and sent them to the beam dump (basically a non-reflecting enclosed box that was thoroughly opaque at those frequencies, but with high thermal conductivity so it didn't overheat). So, all that trouble to make a 355 nm beam, and the left-overs get sent to the beam dump. Heh-heh.
Well, what happens when you stick a business card in that beam dump is pure unadulterated awesome. Where the beam hits, the card explodes. Doesn't burn, explodes. If you leave it in there LONG enough, the remnants may start to burn. See, there is enough moisture in business card paper that when that beam hits, it flashes to steam so fast it cannot get out of the paper fast enough. The steam is superheated and tries to expand. It can't because it is trapped, so it's pressure increases. Paper fiber is a rather poor pressure vessel, so the paper explodes. Once the moisture is gone, then it starts to burn.
And then all of the dust you just created gets all over your optics and the laser efficiency starts to mysteriously drop and your research advisor starts asking probing questions about any unusual activity in the lab over the last few days. Funny as hell though! [/tangent]
This also made my day. :yes:
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Heh heh, lasers are cool
2000 Trillion Watts is a considerable amount of energy. Given 2000 Joules, this equals the amount of energy released by Rk-95 assault rifle bullet (7.62 x 39 mm), or AK-47 if you didn't serve in Finland. So absorbing this energy completely to a human body could potentially be lethal. And that's cool, normally lasers just burn you!
Makes me wonder what kind of interesting things can the instant electric field amplitude do within matter....
[tangent]
Have had my share of lasers too. Normal laser scanners are typically eye-safe (laser class I) as long as they are scanning, i.e. the beam must move. If the scanning stops and the laser fires, the scanners would probably go to class III, and are NOT eye safe. Make no mistake, manufacturers go to extreme lengths to guarantee that the laser does not fire if the beam is not moving! Other possibility is to expand the beam diameter so much that the laser is anyways Class I as they eye cannot possibly gather as much energy, but this tends to increase the size of the things and is not applicable everywhere.
You've probably heard that human eye can see wavelengths up to ~ 700 nm. That was not the case for me, I could see up to around 800 nm of Fraunhofer lines in a dark laboratory. I actually suppose most people would be able to do that, but only if the eye is accomodated, and this does not happen in normal illumination. Well, to cut to the chase, I've actually also seen 785 nm wavelengths in normal room illumination. That was with a 150 mW laser that was used in a Raman system. The system was shining that energy to a spot on a paper, and I observed the paper with a naked eye. First year at work, I know. I actually could see the spot, just faintly. I later on realized how big a risk and dangerous this was, and has then participated more on the laser safety briefing of the new guys... The scattering from the paper is probably what saved my eyes in this case.
We had a class IV laser shining through a system some years ago. As stupid as it is, the laser safety goggles occasionally dampen the energy far too much, so that you cannot see the spot at all. In that case, we discovered that the only way to adjust the direction of the spot was to remove the goggles. It is one of those moments where you really ponder how much of Physics you do know in real life, as it is now really personal. Turned out that I was right, the spot was so large (20 cm x 20 cm) that when the 500 mW of power was spread over it (target was black and scattering), the brightness was well within Class I limits. But I do recall thinking that if I absolutely have to do this, I'll open my weaker eye first, even if I know that this should be safe.
Raman systems are also prone to massive amounts of CW power. We had a Class IVb (800 mW) laser in the lab, which was used to detect certain compounds. The problem is, that 800 mW went to somewhere, and it turned out we were actually measuring smoke coming from the plastic walls of the device. But at least we got a good signal!
The last one I can share was not a laser system, but a solar simulator. My colleagues wanted to test solar cells, and Mika went away and did one simulator. It used a 300 W Cermax bulb (electrical power), that could convert about 50 % of that to radiometric energy, and 3 % of that within the visual region, the rest being spread to IR (the reason such source is used in the evenness of the spectrum, it's hard to equal that). In order to check if the beam was properly focused in a bottleneck area where the beam was supposed to enter a 1 cm x 1 cm area, I just used a piece of A4 covering the bottle neck with it. The mistake became immediately obvious when the power was turned on and the paper evaporated there, leaving a hole of size 1 cm x 1 cm with coaly edges in the paper. Yes, that 150 W of radiometric power was just focused on that 1 cm x 1 cm area, leading to an average irradiance of 1.5 MW / m^2, or equivalent of ~1500 suns (1 sun ~ 1000 W/m^2).
The pilots have a saying that in the beginning, you have all luck an no experience, and the idea is to convert luck to experience before luck runs out. Occasionally, I feel the same with lasers.
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