Skynet is coming.

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paperburn1
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Re: Skynet is coming.

Postby paperburn1 » Tue Jul 03, 2018 8:48 pm

. The ZKZM-500 can reportedly fire a thousand two-second shots, the equivalent of 33 hours of laser power


2000 seconds is 33 minutes
I am not a nuclear physicist, but play one on the internet.

williatw
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Re: Skynet is coming.

Postby williatw » Tue Jul 03, 2018 8:59 pm

paperburn1 wrote:. The ZKZM-500 can reportedly fire a thousand two-second shots, the equivalent of 33 hours of laser power


2000 seconds is 33 minutes


Assuming that the magazine story from the Chinese literally means that yes. But I was speculating that maybe it doesn't; that the Chinese assuming this is legit aren't giving away all the details acccurately purposely. I was postulating what I thought might be a plausible way in which this rifle sized portable laser's alleged abilities might be reasonably explained. And like a kid's magnifying glass it might be designed to aim and focus on as small a target area as possible, making the "burning of skin" or clothes that much easier.

paperburn1
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Re: Skynet is coming.

Postby paperburn1 » Wed Jul 04, 2018 12:22 am

True ,pulsing could extend battery life , focusing would be better but the whole package makes it very iffy in my mind. You have to make too many assumptions to get this thing to work. Physics, making good ideas hard to do. :D
I am not a nuclear physicist, but play one on the internet.

hanelyp
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Re: Skynet is coming.

Postby hanelyp » Wed Jul 04, 2018 6:15 am

Presuming the laser gun does work, mirrors. Retro-reflector corner cubes even. Or for improvised protection, aluminum foil, shiny side out.
The daylight is uncomfortably bright for eyes so long in the dark.

paperburn1
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Re: Skynet is coming.

Postby paperburn1 » Wed Jul 04, 2018 8:17 pm

Realistically, the battery alone would have to weigh several hundred pounds to provide the energy needed to fire a hot laser beam a kilometer. The beam itself would have a hard time once it left the gun. As the beam passes through the air the water molecules in the air—the 'heat' of the beam would disseminate very quickly.. A far cry from the "instant carbonization" threat that is being touted by the chinese,at least at the ranges they are claiming. Cooling of the gun is another factor, no process is 100 percent efficient. and I see no heat sinks or cooling anywhere.
I am not a nuclear physicist, but play one on the internet.

williatw
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Re: Skynet is coming.

Postby williatw » Wed Jul 04, 2018 9:08 pm

paperburn1 wrote:Realistically, the battery alone would have to weigh several hundred pounds to provide the energy needed to fire a hot laser beam a kilometer.


Lithium ion battery charges a built in capacitor; capacitor can discharge several minutes worth of charge in a few seconds in short bursts, much higher power for brief intervals than the batteries standard output. That's got to be what the "for up to two second shot" indicates; after all if it were just the battery direct power why wouldn't the laser just fire continuously for the "1000 shot" interval until the battery itself is discharged? The answer must be that is the amount of time the capacitor can fire before it is exhausted; then the shooter has to wait an unspecified amount of time for the battery to recharge the capacitor. The sniper initially has a "green" indicator light, then an orange light when capacitor is low, finally a "red" light when it is empty and no more fire until recharge cycle takes him back to green.

paperburn1 wrote: The beam itself would have a hard time once it left the gun. As the beam passes through the air the water molecules in the air—the 'heat' of the beam would disseminate very quickly.


Solid state laser broadcasting at a wavelength (near infrared?) that is mostly transparent as practical to water vapor; high power/very short pulse, small tightly focused beam maximum amount of energy in a minimum area. No doubt they looked at the absorption spectra of water vapor and played around with various wavelengths of laser discharge till they found one that worked for the distances indicated. The smaller the "cylinder" of the beam the less debris water vapor or otherwise (dust, pollen, etc.) beam should encounter. The advantage of higher power in short pulses tightly focused also makes it less likely beam will encounter "stuff" drifting into the target path as it travels to the target during the duration of the pulse.



paperburn1 wrote:A far cry from the "instant carbonization" threat that is being touted by the chinese,at least at the ranges they are claiming. Cooling of the gun is another factor, no process is 100 percent efficient. and I see no heat sinks or cooling anywhere.


High power via hypothesized capacitors in short pulses not taxing the limited battery output should easily address the waste heat problem; the aggregate energy isn't that great, therefore less waste heat generated, and one can achieve "instant carbonization" of a very small target area rapidly heated.

paperburn1
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Re: Skynet is coming.

Postby paperburn1 » Thu Jul 05, 2018 1:43 am

BUT BUT ...PHYSICS , Thermodynamics ,OPTICS

Future lasers might have an efficiency of 20-50%. At the low end, a weapon with a 1kJ beam will have to dissipate 4kJ of waste heat with each shot.
Our best lithium-ion batteries have a specific energy of about 1.8 MJ/kg. A single 7.62 NATO round has about 3.3kJ when fired. so your talking two kilo of battery power for each shot to equivalent to a nato round For a laser to have the same effect at this range The soldiers will have to carry around portable power packs, or be plugged in. A super battery material like discussed in the other thread for a laser gun would be more usefully deployed as an explosive warhead'. A direct hit on the power pack of a laser gun will be like a equivalent weight of TNT exploding.
optics would have to be flawless and easily replaceable in the field by a soldier. Any dust or dirt on the lens would be catastrophic if /when fired Have you ever been in the field?
Perhaps the biggest unaddressed problem of laser weapons is their ability to permanently blind anyone who happens to see the beam. In practice, this means anyone within a 5 km radius - roughly the limit of the horizon - is at risk. If a laser beam is powerful enough to incapacitate someone, a reflection off any shiny object - a well-polished car, a window, a doorknob, shiny rivet- will blind anyone unfortunate enough to be in the (reflected) line of fire. Near-IR beams will ignite dust and pollen in the path of the beam; visible light will, obviously, be visible; near-UV will produce a fluorescent glow along the beam. pointing out the position of the shooter
Maybe given time and great development it would be useful in special case scenarios like seal team snipers
Mounted on a platform, very doable, but as a common foot soldier weapon ,no. A M4 is cheaper less prone to failure and field serviceable with the same lethality. China is full of sh!t
I am not a nuclear physicist, but play one on the internet.

williatw
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Re: Skynet is coming.

Postby williatw » Thu Jul 05, 2018 2:25 am

paperburn1 wrote:BUT BUT ...PHYSICS , Thermodynamics ,OPTICS
Future lasers might have an efficiency of 20-50%. At the low end, a weapon with a 1kJ beam will have to dissipate 4kJ of waste heat with each shot.
Our best lithium-ion batteries have a specific energy of about 1.8 MJ/kg. A single 7.62 NATO round has about 3.3kJ when fired.


Using your figures...but lets go with a with a .380 ACP instead of your NATO round, yielding 270J per round. Rifle weighs about 3kg; 1.8MJ/kg * 3= 5.4MJ. Maybe the rifle is .75 battery by weight so 5.4*.75=4.05MJ. Let's optimistically assume 35% efficiency; 4.05MJ*.35= 1.42MJ. Divided by 270J yields 1.42MJ/270J= 5259 shots. In fact if I upped it to a 357 round that's 846J almost 1700 shots; doesn't seem to hateful to me; don't see your big issue there. It is instructive to note that effective bullet rounds don't have to have that much energy; it is the fact of their being concentrated in a small area (point of impact) and yielding up such energy in a thousandth of a second (that is momentary high power) or so is why they are so lethal. Exactly what a battery charged rapidly discharging capacitor powered tightly focused laser could it seems do.

https://en.wikipedia.org/wiki/Muzzle_energy

Causing "unendurable pain" & "carbonizing" if focused on a small enough patch of skin; potentially lethal more like some kind of long range silent invisible (the beam) sniping weapon.

hanelyp
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Re: Skynet is coming.

Postby hanelyp » Thu Jul 05, 2018 7:02 am

I've been toying with the idea of electrically powered slug throwers in place of gunpowder. Energy density in the battery isn't anywhere close to a problem. Power density, particularly for higher energy rounds, does look like a problem. My focus has been on electrically powered air guns, and a compact air pump for the required power and pressure is non-trivial, though a solenoid based system =might= be workable.
The daylight is uncomfortably bright for eyes so long in the dark.

paperburn1
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Re: Skynet is coming.

Postby paperburn1 » Thu Jul 05, 2018 11:12 am

I love the internet, ask and you shall receive. while you did have some innovative solution, physics still wins
(at least with our current technology)
range is one of the major limiting factors
http://panoptesv.com/SciFi/LaserDeathRa ... mLaser.php
I am not a nuclear physicist, but play one on the internet.

williatw
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Re: Skynet is coming.

Postby williatw » Thu Jul 05, 2018 3:21 pm

paperburn1 wrote:I love the internet, ask and you shall receive. while you did have some innovative solution, physics still wins
(at least with our current technology)
range is one of the major limiting factors


Again...using your source:

Damage to Meat

Beam parameters
Beam power: 300 kW
Beam diameter at target: 6 mm
Beam duration: 100 μs
Beam energy: 30 J
Number of pulses: 30
Time between pulses: 67 ms
Total Beam energy: 900 J
Total Beam duration: 2.01 s

Environmental parameters
Ambient temperature: 293 K
Ambient pressure: 101 kPa

Material properties
density: 1000 kg/m3
Heat of fusion: 49 kJ/kg
Heat of vaporization: 2.53 MJ/kg
Heat capacity: 20 kJ/(kg K)
Boiling temperature: 373.2 K
Molar Mass of vapor: 0.01801 kg/mole
Thermal Conductivity: 1 W/(m K)
Ultimate Strength: 500 kPa
Shear Modulus: 3.4 MPa
Cavity Strength: 1.2 MPa
Speed of Sound: 1.54 km/s


Drilling conditions
Vapor pressure: 3.08 MPa
Surface temperature: 485.3 K
Vapor Jet Speed: 487 m/s


Material damage
Blasting Speed: 61.2 m/s
Width of hole: 3.46 cm
Depth of hole: 2.04 cm
Time to excavate hole: 0.334 ms
Aspect ratio: 0.59


Material damage from pulse train
Width of hole: 3.46 cm
Depth of hole: 61.3 cm
Aspect ratio: 17.7



http://panoptesv.com/SciFi/LaserDeathRa ... ction.html

http://panoptesv.com/SciFi/LaserDeathRa ... mLaser.php

http://panoptesv.com/SciFi/LaserDeathRa ... Damage.php
Last edited by williatw on Thu Jul 05, 2018 4:05 pm, edited 1 time in total.

williatw
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Re: Skynet is coming.

Postby williatw » Thu Jul 05, 2018 3:37 pm

How to Build a Laser Death Ray

Diffraction



There is a fundamental physical limit on the ability of lasers to focus on their targets. It is called diffraction. To understand diffraction, you need to understand the behavior of waves.
When a freely propagating wave encounters a barrier, it can curve around the barrier. Think of ripples on the surface of a still pond passing a post sticking out of the water. Similarly, a wall with a single opening will let the wave through the opening, but the edges of the wave will curve out toward the sides, causing the transmitted wave to spread out. This phenomenon is known as diffraction. It happens with every kind of wave in nature. Light is a wave in the electromagnetic field, so light undergoes diffraction. It does not even require an object in the path of the wave, any beam of waves has a tendancy to spread out to the sides due to this effect.

The smaller the wavelength of a wave in comparison to the size of the obstruction or opening, or the width of the beam, the less the wave diffracts. Since visible light has a very small wavelength, this is why light seems to travel in straight lines. It takes very narrow objects, such as hairs or thin scratches, to get noticable diffraction. This is easy to demonstrate with a laser pointer in a darkened room. Shine the beam at a wall. Now put a hair in the beam. You will see a streak appear on the wall through the laser dot perpendicular to the hair. The streak is the light diffracting around the hair.

When a laser beam is propagating freely, it will naturally tend to expand. This means that if you try to focus the beam down to a tiny point at a distant target, the beam might spread out to a much larger spot by the time it gets there. The amount the beam expands depends on the ratio of the initial width of the beam to the wavelength of the beam. In fact, we can determine the smallest possible spot size into which you can focus the beam: if we denote the diameter of the mirror, lens, or other opening in the laser or focusing element as D, the wavelength of the light as L, and the distance to the target as R, then the diameter of the smallest spot, S, is given by


S = 1.2 R L / D.

Make sure you use the same units for R, L and D (this will give S in that unit as well). The term 1.2 L / D is sometimes called the divergence angle A (even though the beam will be converging if S < D). With this terminology,

S = R A.

For example, a laser that emits 5×10-7 meter wavelength light (or 0.5 microns, this puts it in the visible green) that is focused through a 0.1 meter lens at a target 1000 meters (1 km) away will have a minimum spot size of 6×10-3 meters (6 millimeters) and a divergence angle of 6×10-6 radians.
The above formulas are only valid when R is much larger than D.
The details of near field diffraction are too complex to cover here, although you will not be too far wrong using the formulas as long as R > D.


http://panoptesv.com/SciFi/LaserDeathRa ... ction.html

The worked out example isn't that far off from what we are talking about for the Chinese laser. Maximum distance is actually less, 800M rather than a 1000; wavelength for infrared probably around 700nm, 0.1M or 10cm(or about 4 inches) doesn't seem unreasonable size for the optics for our sniping rifle.

paperburn1
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Re: Skynet is coming.

Postby paperburn1 » Thu Jul 05, 2018 4:34 pm

I think the bottom line is best described by an old welsh proverb.
If the landlord says he has a shotgun , you pay the rent on time until your sure. :D :D
I am not a nuclear physicist, but play one on the internet.

ladajo
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Re: Skynet is coming.

Postby ladajo » Thu Jul 05, 2018 4:46 pm

China, like Russia, and others loves the idea of information campaigns. They are comparably very cheap when compared to actual functional capabilities and capacities. The part those who like information campaigns don't tend to understand often are the unintended consequences. Sadam comes to mind. As do others, such as Hitler.

I would apply to old adages here; "If it sounds to good to be true...", and, "Show me."

Burning a hole in a human at 800m is a substantial accomplishment at the shoulder fired level. There are so many competing issues, the most basic of which is atmospherics, as well as the claimed magazine depth for the required power levels delivered on target at range. I remain highly sceptical, as I do of many claimed capabilities out there. I too think the PLA is "Full of shit" in many ways.
The development of atomic power, though it could confer unimaginable blessings on mankind, is something that is dreaded by the owners of coal mines and oil wells. (Hazlitt)
What I want to do is to look up C. . . . I call him the Forgotten Man. (Sumner)

williatw
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Re: Skynet is coming.

Postby williatw » Thu Jul 05, 2018 5:12 pm

ladajo wrote:Burning a hole in a human at 800m is a substantial accomplishment at the shoulder fired level. There are so many competing issues, the most basic of which is atmospherics, as well as the claimed magazine depth for the required power levels delivered on target at range. I remain highly sceptical, as I do of many claimed capabilities out there.


Well ladajo out of fairness the Chinese info release is only claiming things like "carbonizing human (skin)" and causing "pain beyond endurance" & "potentially lethal". Nothing about holes being drilled in people. Causing painful burns on exposed skin (or skin under normal clothes) isn't the same as "drilling holes" in human flesh. The other data I posted is from the link(s) posted by paperburn1 (the part about "holes" being made in "meat"). My understanding is that said holes are caused not by the vaporization of the flesh directly by the pulsed laser but by the superheated steam rapidly expanding causing the widening damage; more mechanical than thermal. Also 800M is the stated range limit; maybe the optimum distance for effective use is allot closer.

ladajo wrote:I too think the PLA is "Full of shit" in many ways.


Well if they mass deploy to their police/military snipers we should know soon enough. Sure someone would be able to get one of the rifles somehow for our guys to take it apart and figure it out (if it exists).


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