elukka
Junior Member
Posts: 73
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Post by elukka on Jan 19, 2018 20:48:53 GMT
Regarding the idea of lasers that fire intermittently, I think that's unrelated to whether it's a pulsed laser or not. Like OMGitsWTF says, the pulsing typically happens on very short timescales. The kind of lasers OP talks about could be either pulsed or continuous (on those very short timescales), and in essence would be the result of carrying an "oversized" laser in the sense that it's more powerful than a laser that you could continuously power and/or cool.
The idea seems good to me. After all, why bother with the capability to fire your laser for hours if combat is likely to last seconds? Rely on capacitors and heat sinks and go as powerful as you can while lasting long enough for your typical combat timescales. If you survive, you'll likely have plenty time to rid yourself of the waste heat and recharge your capacitor banks.
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Post by bigbombr on Jan 19, 2018 21:13:55 GMT
Regarding the idea of lasers that fire intermittently, I think that's unrelated to whether it's a pulsed laser or not. Like OMGitsWTF says, the pulsing typically happens on very short timescales. The kind of lasers OP talks about could be either pulsed or continuous (on those very short timescales), and in essence would be the result of carrying an "oversized" laser in the sense that it's more powerful than a laser that you could continuously power and/or cool. The idea seems good to me. After all, why bother with the capability to fire your laser for hours if combat is likely to last seconds? Rely on capacitors and heat sinks and go as powerful as you can while lasting long enough for your typical combat timescales. If you survive, you'll likely have plenty time to rid yourself of the waste heat and recharge your capacitor banks. Being able to keep on firing is one of the main advantages of lasers though. IRL, nothing stops you from firing at stupendous ranges in the hope of burning a sensor or something. In game, all my lasers start firing at 1 Mm or 10 Mm.
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Post by fallingaggressively on Jan 20, 2018 0:11:49 GMT
Elukka is spot on, but wether it is a pulse laser or not may still be a factor if there is significant differences in damage/utility and mass.
If I can get my head around the output formulas and methods of determining the mass of the laser, then I should be able to get an idea of which is better; a big blast laser or a number of long fire lasers.
Looking at CoaDE capacitors, it’s looking like you can store about a mega joule per ton. So I figure a mega ton for a one second pulse on a gigawatt laser. If I can find a reasonable gigawatt laser design I’ll use that for my first run guess work.
Again though, would a one second firing of a pulse laser be better or worse? I read Luke Campbell’s site and it was convincing about their penetration value.
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Post by apophys on Jan 20, 2018 4:55:50 GMT
Looking at CoaDE capacitors, it’s looking like you can store about a mega joule per ton. So I figure a mega ton for a one second pulse on a gigawatt laser. Looking at the capacitors for my railguns, it seems to be right around 0.75 MJ/ton after the drop to 45% efficiency (using BOPP). So ~1.667 MJ/ton input charge. A gigawatt reactor is 9.49 tons; with accessories (radiators, laser turret(s) ) that should be around 50 tons of mandatory equipment. I'll consider 12 tons of capacitor; it seems reasonable here. 9 MJ storage (20 MJ input) gives you a pulse every 20 milliseconds, plus discharge time. The shorter your discharge time, the higher the intensity of your pulse. Ingame railguns suggest that firing times in the range of 0.1 ms are feasible, but that may not remain true for lasers. The result is that your peak power is about 90 times more than your constant draw laser, improving intensity by 90 times. This means you can do nonzero damage 9.54 times farther than a constant laser can. If you do choose to engage at this new distance, ignoring shock effects, your rate of drilling through material will be reduced to 1/200 of the constant laser (which is low, but nonzero, unlike the constant laser at this distance; materials can radiate away all heat below a certain intensity of laser). At the same distance as the constant laser, and still ignoring shock effects, the pulsed laser will drill at about 45% of the rate of the constant laser. Pulses induce shock effects, which improves the rate of damage (and provides a different damage mechanic that may necessitate otherwise sub-optimal armor choices in the defender). I don't have a way to quantify those, though. Using capacitors is probably not the best way to pulse a laser, but it should work.
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Post by fallingaggressively on Jan 22, 2018 3:59:40 GMT
Looking at CoaDE capacitors, it’s looking like you can store about a mega joule per ton. So I figure a mega ton for a one second pulse on a gigawatt laser. Looking at the capacitors for my railguns, it seems to be right around 0.75 MJ/ton after the drop to 45% efficiency (using BOPP). So ~1.667 MJ/ton input charge. A gigawatt reactor is 9.49 tons; with accessories (radiators, laser turret(s) ) that should be around 50 tons of mandatory equipment. I'll consider 12 tons of capacitor; it seems reasonable here. 9 MJ storage (20 MJ input) gives you a pulse every 20 milliseconds, plus discharge time. The shorter your discharge time, the higher the intensity of your pulse. Ingame railguns suggest that firing times in the range of 0.1 ms are feasible, but that may not remain true for lasers. The result is that your peak power is about 90 times more than your constant draw laser, improving intensity by 90 times. This means you can do nonzero damage 9.54 times farther than a constant laser can. If you do choose to engage at this new distance, ignoring shock effects, your rate of drilling through material will be reduced to 1/200 of the constant laser (which is low, but nonzero, unlike the constant laser at this distance; materials can radiate away all heat below a certain intensity of laser). At the same distance as the constant laser, and still ignoring shock effects, the pulsed laser will drill at about 45% of the rate of the constant laser. Pulses induce shock effects, which improves the rate of damage (and provides a different damage mechanic that may necessitate otherwise sub-optimal armor choices in the defender). I don't have a way to quantify those, though. Using capacitors is probably not the best way to pulse a laser, but it should work. A 10x range increase for just 12 tons of capacitor! I can see why you want the game limitations fixed.
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Post by lucubratory on Jan 24, 2018 2:27:26 GMT
The advantage of pulsed lasers is that the little amount of armor material that they vaporize expands like an explosion. This imposes mechanical stresses on the surrounding material. If the pulses contain enough energy, they can break apart and shear off large amounts of surrounding material. Digging out armor in this way requires much less energy per kg than fully vaporizing the material. So, a pulsed laser will have better penetration rates than a continuous laser of the same average power. Luke Campbell states that 40x better penetration rate is possible, although I believe this depends strongly on how strong the armor is. This is also why I do not believe some of the most effective anti-laser armor materials on COADE are not realistic. Aerogel is great in terms of vaporization energy per kg... but it is so weak that any plasma expansion will blow out huge chunks of it. That's a fair point about the gels. Is there any real-world data on impregnated or composite gels? For example, a carbon fibre gyroid or octet truss (or both) that's been suffused with gel before the solvent is removed and replaced with gas. Could interrupt crack transmission in aerogels and help provide them with greater compressive and tensile strength on a macro level. It would make the materials less ablative though, and you'd want to be careful about whatever material you reinforce with transferring heat. Edit: as in be careful the material you're using to reinforce the aerogel doesn't undermine the whole point of using aerogel by having too low a vaporisation energy/kg.
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Post by fallingaggressively on Jan 24, 2018 17:46:10 GMT
Wonder if it means pulse lasers would be effective against radiators?
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