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GRASERS

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GRASERS
Post by Varangian   » Thu Jul 14, 2022 8:17 am

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I want to say to everyone that your knowledge is unbelievable! A fantastic resource.

Grasers- gamma ray lasers I see that, but what is the difference, how do they inflict damage, does one do something better than the other? Aside from size and weight why a graser vs a laser?

I read in the books about their 'size'- SD size or BC size and it kind of reminds me of wet navy guns- 16inch on a BB vs 8 inch on a CA for instance.
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Re: GRASERS
Post by Jonathan_S   » Thu Jul 14, 2022 9:29 am

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Varangian wrote:I want to say to everyone that your knowledge is unbelievable! A fantastic resource.

Grasers- gamma ray lasers I see that, but what is the difference, how do they inflict damage, does one do something better than the other? Aside from size and weight why a graser vs a laser?

I read in the books about their 'size'- SD size or BC size and it kind of reminds me of wet navy guns- 16inch on a BB vs 8 inch on a CA for instance.

The 'size' is very much intended to invoke that thought. Though given the broadside layout and large number of mounts it was probably intended slightly more to invoke the 12 vs 18 vs 32 pounder cannon of the age of sail. But either way, the size and power of the weapon scales up or down with larger ships mounting both more weapons but also individually larger and more powerful ones.

As for the differences in effects between laser and graser I'm just going to quote from the section Weapon Effects and Armor: How Does a Weapon Damage the Target? in the essay An Introduction to Modern Starship Armor Design from the anthology In Fire Forged
In Fire Forged: Introduction to Modern Starship Armor Design wrote:Weapons designers prefer shorter wavelength photons because they are (up to a point) easier to focus at the ranges of modern beam weapons. Shorter wavelength photons also tend to penetrate more deeply into armor and deposit into denser spacecraft structures like impeller nodes, fusion reactors, and weapon mounts. If preferred, the reader can imagine the shorter wavelength packets of energy in a graser beam “slipping” in between atoms in less dense materials to penetrate more deeply into the target and hitting the more closely packed atoms of more dense materials. Shorter wavelength photons also (again up to a point) deposit more energy and thus do more damage to any structure they hit. Needless to say, any characteristics which make short wavelength photons the friends of weapon designers do not to endear them to armor designers. The downside to shorter wavelength photons is that they tend to be harder to efficiently produce than their longer wavelength siblings. That means less energy on target for a given amount of input energy from the fusion reactors for ship mounted weapons or the nuclear device for bomb-pumped ones. This is one fundamental physical reason why graser mounts are usually best practically mounted only on heavy cruisers or larger.
Wavelength is a microscopic property of the beam. We now turn from the microscopic to the macroscopic beam properties. Each of the countless photons possesses a tiny quantity of energy and all beam photons flow together at the speed of light to their target. Adding up all of the energy of each photon in the laser beam gives us the delivered energy to target (DETT). Dividing that energy by the amount of time that the beam pulse lasts gives the total beam power. A full treatment of how these combine with beam spot size on target, pulse time, and a variety of other factors to do damage requires much more time and space than we have here. Two useful generalizations can be made without extensive simulation. The first and most obvious is that high DETT does more damage because it vaporizes, atomizes, and then ionizes more of the target. The second and less intuitive fact is that very high-power beams (tens of billions of gigawatts or more) begin to produce unique shock effects in solid matter. Hence, in general, it is best for a weapon designer to deposit as much energy as possible into the target in as little time as possible.
As noted graser mounts are larger than their laser counterparts -- and sometimes you'd prefer to have more, lighter, weapons instead of fewer heavier ones. (Or you simply don't have room for any of the larger weapons)

And while you could presumably scale down a graser to the point it was as small as any given laser mount presumably the output power would have dropped so much that the laser mount would be more destructive (despite having lower frequency photons)
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Re: GRASERS
Post by Theemile   » Thu Jul 14, 2022 10:25 am

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Jonathan_S wrote:
Varangian wrote:I want to say to everyone that your knowledge is unbelievable! A fantastic resource.

Grasers- gamma ray lasers I see that, but what is the difference, how do they inflict damage, does one do something better than the other? Aside from size and weight why a graser vs a laser?

I read in the books about their 'size'- SD size or BC size and it kind of reminds me of wet navy guns- 16inch on a BB vs 8 inch on a CA for instance.

The 'size' is very much intended to invoke that thought. Though given the broadside layout and large number of mounts it was probably intended slightly more to invoke the 12 vs 18 vs 32 pounder cannon of the age of sail. But either way, the size and power of the weapon scales up or down with larger ships mounting both more weapons but also individually larger and more powerful ones.

As for the differences in effects between laser and graser I'm just going to quote from the section Weapon Effects and Armor: How Does a Weapon Damage the Target? in the essay An Introduction to Modern Starship Armor Design from the anthology In Fire Forged
In Fire Forged: Introduction to Modern Starship Armor Design wrote:Weapons designers prefer shorter wavelength photons because they are (up to a point) easier to focus at the ranges of modern beam weapons. Shorter wavelength photons also tend to penetrate more deeply into armor and deposit into denser spacecraft structures like impeller nodes, fusion reactors, and weapon mounts. If preferred, the reader can imagine the shorter wavelength packets of energy in a graser beam “slipping” in between atoms in less dense materials to penetrate more deeply into the target and hitting the more closely packed atoms of more dense materials. Shorter wavelength photons also (again up to a point) deposit more energy and thus do more damage to any structure they hit. Needless to say, any characteristics which make short wavelength photons the friends of weapon designers do not to endear them to armor designers. The downside to shorter wavelength photons is that they tend to be harder to efficiently produce than their longer wavelength siblings. That means less energy on target for a given amount of input energy from the fusion reactors for ship mounted weapons or the nuclear device for bomb-pumped ones. This is one fundamental physical reason why graser mounts are usually best practically mounted only on heavy cruisers or larger.
Wavelength is a microscopic property of the beam. We now turn from the microscopic to the macroscopic beam properties. Each of the countless photons possesses a tiny quantity of energy and all beam photons flow together at the speed of light to their target. Adding up all of the energy of each photon in the laser beam gives us the delivered energy to target (DETT). Dividing that energy by the amount of time that the beam pulse lasts gives the total beam power. A full treatment of how these combine with beam spot size on target, pulse time, and a variety of other factors to do damage requires much more time and space than we have here. Two useful generalizations can be made without extensive simulation. The first and most obvious is that high DETT does more damage because it vaporizes, atomizes, and then ionizes more of the target. The second and less intuitive fact is that very high-power beams (tens of billions of gigawatts or more) begin to produce unique shock effects in solid matter. Hence, in general, it is best for a weapon designer to deposit as much energy as possible into the target in as little time as possible.
As noted graser mounts are larger than their laser counterparts -- and sometimes you'd prefer to have more, lighter, weapons instead of fewer heavier ones. (Or you simply don't have room for any of the larger weapons)

And while you could presumably scale down a graser to the point it was as small as any given laser mount presumably the output power would have dropped so much that the laser mount would be more destructive (despite having lower frequency photons)


Adding to what Jonathan said, Lasers are usually described in their effect as stiletto's, and Grasers as Sledgehammers. So a Laser will have a focused tight beam, capable of cutting entirely through a ship surgically, where Grasers impact over a "large" area, imparting it's energy explosively into the surface, breaking it into component atoms, then battering through to the next layer.
******
RFC said "refitting a Beowulfan SD to Manticoran standards would be just as difficult as refitting a standard SLN SD to those standards. In other words, it would be cheaper and faster to build new ships."
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Re: GRASERS
Post by kzt   » Thu Jul 14, 2022 1:48 pm

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A 'laser' in the Honorverse is an x-ray laser. So it also penetrates into the depth of the material like all x-rays do. So you don't just get energy deposition on the surface, you get energy deposition into the depth of the material.

A graser is basically a hard x-ray laser. These are deeply penetrating and deposit energy deeply into the material.

This results in the entire structure of the target exploding as you turn material inside the structure of the target into super-heated plasma, and this tears the structure around it apart.

This is in addition to the enormous dose of x-rays or gamma rays scattered off the plasma cloud and penetrate the area around the impact. This is highly unfavorable to the life expectancy of those people who are not directly killed by the beam, the explosions, or the hypersonic fragmentation.
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Re: GRASERS
Post by Loren Pechtel   » Sat Jul 16, 2022 4:20 pm

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First, in modern scientific usage grasers do not exist at least as used in the Honorverse. He's using the old school approach that gamma rays are higher frequency than x-rays, but for some reason the scientific community has shifted towards x-rays being from electron shell activity (generally by kicking loose an electron and then using the photon that is released when it rejoins) and gamma rays being from nucleus activity. Generally gamma rays are higher frequency but there is a substantial overlap region. Since we see no other manifestation of being able to mess with the nucleus of atoms it's pretty clear that Honorverse "grasers" are based on electrons and thus are x-ray.

Second, the ability to focus comes down to how many wavelengths fit across your mirror. You can see better, or make your beam more precise (it's the same issue whether you're looking at incoming or outgoing photons) the higher the frequency. Thus for a given mount size the energy will be more concentrated at the target when you use a higher frequency and thus will be more destructive. (Look at how vague radio astronomy images generally are even when they use an array of antennas. The really good images are from using planet-spanning virtual antennas.)

Third, the higher the frequency the more energy delivered per photon and thus the higher the possible energy of the beam for a certain amount of lasing material.

Thus you end up with a narrower, more powerful beam when you increase the frequency.
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Re: GRASERS
Post by kzt   » Sat Jul 16, 2022 5:32 pm

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Loren Pechtel wrote:
Thus you end up with a narrower, more powerful beam when you increase the frequency.

Technically, a multi-meter gamma ray laser would have so little beam divergence that the beam diameter doubles at light-hours range.

Which isn't how it works in the Honorverse because 'reasons'.
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Re: GRASERS
Post by tlb   » Sat Jul 16, 2022 6:49 pm

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Loren Pechtel wrote:Thus you end up with a narrower, more powerful beam when you increase the frequency.

kzt wrote:Technically, a multi-meter gamma ray laser would have so little beam divergence that the beam diameter doubles at light-hours range.

Which isn't how it works in the Honorverse because 'reasons'.

Here are the equations that I got from Wikipedia for Guassian beams:

For Gaussian beams (where the energy is highest in the center and drops rapidly as you measure to the edge) the beam width follows this equation: w(z) = w(0) * squareroot(1 + (z/R)**2),

where z is the distance from the source and R is the Rayleigh distance. For distances small compared to R the beam width is about the width at the source (which is some fraction of the size the end of the laser) and for distances much greater than R the beam width increases linearly with distance. The equation for the Rayleigh distance is: R = pi * (w(0)**2 / L),

where L is the wavelength of the emitted radiation. This is a simplification based on the wavelength being much smaller than w(0).

The wavelength of an X-ray is in the vicinity of 0.3 nanometers (exponent of -9) and for gamma rays is in the region of 30 femtometers (exponent of -15). If we try those figures we get distances that are nearly a light second or more for the X-ray laser. So we should not worry about getting energy to the target, provided we can actually hit it.
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Re: GRASERS
Post by Brigade XO   » Sat Jul 16, 2022 6:55 pm

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kzt wrote:
Loren Pechtel wrote:
Thus you end up with a narrower, more powerful beam when you increase the frequency.

Technically, a multi-meter gamma ray laser would have so little beam divergence that the beam diameter doubles at light-hours range.

Which isn't how it works in the Honorverse because 'reasons'.


Somehow I wonder about the potential ability of a ship's weapons systems to calculate a proper aim point against an opponent's ship by graser at "a couple of light hours"....just saying.
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Re: GRASERS
Post by ThinksMarkedly   » Sat Jul 16, 2022 7:16 pm

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Loren Pechtel wrote:First, in modern scientific usage grasers do not exist at least as used in the Honorverse. He's using the old school approach that gamma rays are higher frequency than x-rays, but for some reason the scientific community has shifted towards x-rays being from electron shell activity (generally by kicking loose an electron and then using the photon that is released when it rejoins) and gamma rays being from nucleus activity. Generally gamma rays are higher frequency but there is a substantial overlap region. Since we see no other manifestation of being able to mess with the nucleus of atoms it's pretty clear that Honorverse "grasers" are based on electrons and thus are x-ray.


We do know it involves gravitational technology somehow. And since the same grav tech can be used to make nuclear fusion, it should be possible to use it to somehow mess with the nuclei and produce gamma rays. Not that I would expect a controlled nuclear fusion happening on the graser emitters.

The point being that we don't know how they do it in the first place, so we can't dismiss the possibility that it is way into the gamma ray range.

Though it's entirely possible that the nomenclature has nothing to do with the scientific principle. Like you're proposing, if they simply achieve a much higher frequency ("towards gamma ray range"), the name "graser" might have simply stuck, like the "lasers" being used where "xrasers" would have probably been more correct but unpronounceable. (You could attempt to pronounce the X as the Greek Chi "Χ", which is the letter the Romans copied in the first place, so it would come out as "khraser" or "chraser" as in "loch" -- or as in LaTeΧ).

By the way, any masers?
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Re: GRASERS
Post by tlb   » Sat Jul 16, 2022 7:48 pm

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Loren Pechtel wrote:Thus you end up with a narrower, more powerful beam when you increase the frequency.

kzt wrote:Technically, a multi-meter gamma ray laser would have so little beam divergence that the beam diameter doubles at light-hours range.

Which isn't how it works in the Honorverse because 'reasons'.


Brigade XO wrote:Somehow I wonder about the potential ability of a ship's weapons systems to calculate a proper aim point against an opponent's ship by graser at "a couple of light hours"....just saying.

No need to worry about that, since by author's fiat the effective range of energy weapons is much less. Orders of magnitude less than the Rayleigh length, so no need to worry about beam divergence.
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