What would the range of a laser weapon be in space?

[kg]

Unlikely, since they like lasers are just EMF.

That's why I asked...

EMF? Do you mean lasars that are entirely make-believe and fictional?

 

[sentrynox]

What's a neutral laser?

What's a plasma laser?

Plasma laser is a laser that use plasma as a mean for amplification. Our sun is a giant plasma in itself, so in theory it could be used to power a laser. The US Air force did develop such kinds of laser to carry in their plane, as it is much smaller and powerful than the other kinds of lasers that being developed.

The Neutral laser is a theorical laser beam that have been work on by the US and the USSR in the 70's to the 80's for the SDI project. Actually it was refer as a NPB accelerator (for neutron particle beam) and was developed to be used in space as it wasn't subject to the side effects of traveling through space, therefore its path and strength wouldn't be altered.

Both the US and the USSR drop the project as deemed too complex (or too dangerous if you ask me, because it was believed that if such neutral laser was used on our planet (not in space here), it could have cause the complete obliteration of our planet... It is also believed that the Russian rumored Elipton super weapon is just that... A neutral laser capable of destroying our planet.

 

[MeteorWayne]

Unlikely, since they like lasers are just EMF.

That's why I asked...

EMF? Do you mean lasars that are entirely make-believe and fictional?

Sorry, bad typing on my part I meant EM radiation (i.e. light and microwaves)

I don't know what you thought I meant by EMF. ELecotromagnetic waves (and hence lasers an masers) are certainly not fictional.

 

[MeteorWayne]

What's a neutral laser?

What's a plasma laser?

Plasma laser is a laser that use plasma as a mean for amplification. Our sun is a giant plasma in itself, so in theory it could be used to power a laser. The US Air force did develop such kinds of laser to carry in their plane, as it is much smaller and powerful than the other kinds of lasers that being developed.

The Neutral laser is a theorical laser beam that have been work on by the US and the USSR in the 70's to the 80's for the SDI project. Actually it was refer as a NPB accelerator (for neutron particle beam) and was developed to be used in space as it wasn't subject to the side effects of traveling through space, therefore its path and strength wouldn't be altered.

Both the US and the USSR drop the project as deemed too complex (or too dangerous if you ask me, because it was believed that if such neutral laser was used on our planet (not in space here), it could have cause the complete obliteration of our planet... It is also believed that the Russian rumored Elipton super weapon is just that... A neutral laser capable of destroying our planet.

As I have suggested elesewhere, Perhaps you should confine your comments to The Unexplained. This type of unsupported stuff will not be tolerated here in Physics.

For example, in this forum, you will be required to support your assertions that:

"or too dangerous if you ask me, because it was believed that if such neutral laser was used on our planet (not in space here), it could have cause the complete obliteration of our planet"
or:
"It is also believed that the Russian rumored Elipton super weapon is just that... A neutral laser capable of destroying our planet"

In this forum (Physics) you are required to back up this statement with facts, or you must withdraw the statement.

Are you prepared to defend your asertions with hard facts?

Moderator Meteor Wayne

 

[sentrynox]

What's a neutral laser?

What's a plasma laser?

Plasma laser is a laser that use plasma as a mean for amplification. Our sun is a giant plasma in itself, so in theory it could be used to power a laser. The US Air force did develop such kinds of laser to carry in their plane, as it is much smaller and powerful than the other kinds of lasers that being developed.

The Neutral laser is a theorical laser beam that have been work on by the US and the USSR in the 70's to the 80's for the SDI project. Actually it was refer as a NPB accelerator (for neutron particle beam) and was developed to be used in space as it wasn't subject to the side effects of traveling through space, therefore its path and strength wouldn't be altered.

Both the US and the USSR drop the project as deemed too complex (or too dangerous if you ask me, because it was believed that if such neutral laser was used on our planet (not in space here), it could have cause the complete obliteration of our planet... It is also believed that the Russian rumored Elipton super weapon is just that... A neutral laser capable of destroying our planet.

As I have suggested elesewhere, Perhaps you should confine your comments to The Unexplained. This type of unsupported stuff will not be tolerated here in Physics.

For example, in this forum, you will be required to support your assertions that:

"or too dangerous if you ask me, because it was believed that if such neutral laser was used on our planet (not in space here), it could have cause the complete obliteration of our planet"
or:
"It is also believed that the Russian rumored Elipton super weapon is just that... A neutral laser capable of destroying our planet"

In this forum (Physics) you are required to back up this statement with facts, or you must withdraw the statement.

Are you prepared to defend your asertions with hard facts?

Moderator Meteor Wayne

Then I shall ask you, are you prepared for the truth?
For the Elipton super weapon, my assertions are coming from the declaration made by Vladimir Jirinovski in its speech in Vienna, Austria of the 21 December 1993. You can look upon it, but of course, its from the political realm and might not apply it. But in everything there is a part of truth.
As for the danger of neutral lasers, it comes from European references as well as from US intelligences.
Also keep in mind that I am a french speaker and researcher, so my translations might lack accuracy in their English forms...

If you want to know more about the neutral particle beam, then you must know that common lasers and charged particles beam have an electric charge that can interact with itself by repulsing its own particles, which limits its effectiveness and its range. Also such charged particle beams are influence by our planet magnetic field in a way that cannot be predicted.

Therefore only neutral particle beams can travel without interacting too much with its environment thus keeping its effectiveness much longer than other kinds of beams. So such beam could travel easily through our atmosphere and space.

As for common lasers, they do not work well inside our atmosphere because their radiations tend to ionized the surrounding atmosphere after reaching a certain energetic threshold thus causing molecular ionization and air conductivity that triggers "slamming" phenomenons that destroy the laser beam over certain range.

The problem for such NPB is that it is hard to produce as only charged particle beams can be accelerated inside a magnetic field, so the technique at creating such beam consist at "photoneutralizing" them by making the beam going through a laser cavity.

The Los Alamos Laboratory as well as McDonnell Douglas Aeronautics have worked on such lasers.
What makes them so powerful is that they are the perfect way to deliver energy to matter, so a very nicely focused beam of a NPB, could potentially destroyed everything in its path...

For the matter some of the information above can be found in Science et Vie mag:917, February 1994, page 50... But it is in French...

AS for the plasma laser, a team at Michigan University devise the proof of concept and was published in December 1992.
The laser goes accross a plasma which cause shockwaves that accelerates the beam.

Their first prototype could produce 55tW in a raction of a picosecond. Their next goal was to produce a laser beam of 1000tW of power, but that one have never been published in so far...
They were hoping to use this technique to generate X-ray laser beams.

 

[MeteorWayne]

Then I shall ask you, are you prepared for the truth?
For the Elipton super weapon, my assertions are coming from the declaration made by Vladimir Jirinovski in its speech in Vienna, Austria of the 21 December 1993. You can look upon it, but of course, its from the political realm and might not apply it. But in everything there is a part of truth.

You apparently don't understand how things work in the hard science fora. You have made the assertion. It is not my job to look it up, it is yours to back up what you have said.

As for the danger of neutral lasers, it comes from European references as well as from US intelligences.
Also keep in mind that I am a french speaker and researcher, so my translations might lack accuracy in their English forms...

Sorry, no good. A laser is a light beam. It is by definition neutral. What is different about a "Neutral laser"?

If you want to know more about the neutral particle beam, then you must know that common lasers and charged particles beam have an electric charge that can interact with itself by repulsing its own particles, which limits its effectiveness and its range. Also such charged particle beams are influence by our planet magnetic field in a way that cannot be predicted.

Sorry again, but incorrect. First of all, a particle beam is NOT a laser. Laser beams are pure light, and have no charge.
If you are talking about particle beams, then they are not lasers. Please get your terminology correct.

Therefore only neutral particle beams can travel without interacting too much with its environment thus keeping its effectiveness much longer than other kinds of beams. So such beam could travel easily through our atmosphere and space.

Again, a particle beam is not a laser

As for common lasers, they do not work well inside our atmosphere because their radiations tend to ionized the surrounding atmosphere after reaching a certain energetic threshold thus causing molecular ionization and air conductivity that triggers "slamming" phenomenons that destroy the laser beam over certain range.

correct

The problem for such NPB is that it is hard to produce as only charged particle beams can be accelerated inside a magnetic field, so the technique at creating such beam consist at "photoneutralizing" them by making the beam going through a laser cavity.

The Los Alamos Laboratory as well as McDonnell Douglas Aeronautics have worked on such lasers.
What makes them so powerful is that they are the perfect way to deliver energy to matter, so a very nicely focused beam of a NPB, could potentially destroyed everything in its path...

For the matter some of the information above can be found in Science et Vie mag:917, February 1994, page 50... But it is in French...

unable to make much sense of this

AS for the plasma laser, a team at Michigan University devise the proof of concept and was published in December 1992.
The laser goes accross a plasma which cause shockwaves that accelerates the beam.

Their first prototype could produce 55tW in a raction of a picosecond. Their next goal was to produce a laser beam of 1000tW of power, but that one have never been published in so far...
They were hoping to use this technique to generate X-ray laser beams.

[/quote]

Please provide a reference for this.

 

[sentrynox]

Well, I think I know where the confusion came from... I got Russian sources talking about a neutral laser (might be wrong translation there), while the US refer to neutral particle beams.

Anyhow a normal laser might be neutral by definition but the fact is that it is still ionizing the surrounding atmosphere around it... So in a physical sense, it reacts to its environment therefore it isn't really neutral by definition.

As for the references for the plasma laser, I can provide french sources but not American ones...
Ref: Science & Vie N°903, Décembre 92, page 30

Keep in mind that those are old stuff, and from what I have seen, very little have transpire of those projects since then, so I am not surprised that few seems to know about those things. So I am sorry if I didn't felt to explain those things more in details :?

 

[sentrynox]

You apparently don't understand how things work in the hard science fora. You have made the assertion. It is not my job to look it up, it is yours to back up what you have said.


By the way I used to talk with diagrams and schematics in Paleontology, while discussing with peoples that I already know, so thats a bit new for me here, and understand your reaction to such claims made here. But do not judge a book by its cover, it might close you unexpected doors! I guess I grew complacent over time, and it shows...

 

[kg]

Could he possibly be talking about a Ion laser? I don't see anything in the wiki to suggest that this would make a good weapon. http://en.wikipedia.org/wiki/Ion_laser Or how about this? http://en.wikipedia.org/wiki/Gas_dynamic_laser

 

[sentrynox]

Could he possibly be talking about a Ion laser? I don't see anything in the wiki to suggest that this would make a good weapon. http://en.wikipedia.org/wiki/Ion_laser Or how about this? http://en.wikipedia.org/wiki/Gas_dynamic_laser

I am not talking about an Ion laser! And the stuff I am talking about won't be found in Wikipedia...
The world doesn't revolve around wiki at all, I hope peoples won't think so at least!

 

[DrRocket]

If you want to know more about the neutral particle beam, then you must know that common lasers and charged particles beam have an electric charge that can interact with itself by repulsing its own particles, which limits its effectiveness and its range. Also such charged particle beams are influence by our planet magnetic field in a way that cannot be predicted.

What in the world are you talking about ?

LASER stands for Light Amplification by Stimulated Emissioin of Radiation. The important word is "light". The emissions of a laser are photons. Photons carry no charge. None at all.

Now certainly charged particle beams involve electrical charges -- that is whey they are called charged particle beams. And of course the repulsion among particles of like charge tends to spread the beam, and that is a problem for a weapon. But lasers do not have that particular problem.

 

[kelvinzero]

I found these two links.. Didnt examine in great detail but I think the conclusion is that there are theoretical limits on how low the divergence of a laser can be, dependent among other things on the frequency of the laser.

http://www.us-lasers.com/beam_divergence.htm
http://en.wikipedia.org/wiki/Beam_divergence

 

[jim48]

I could have answered this one right off the top of my head, but as the only real, genuine, bonafide, honest-to-God scientist out here, I checked with my Mark IV, Series 80, Hyper-Electric Neutron Gravitator and the answer is: Virtually unlimited range, if you define a laser as a light beam. It is thought that light travels in waves but it really doesn't in space. Then we have to contend with dark mattter. A laser beam's range is unlimited until it runs into something, according to what I have here in the lab.

 

[MeteorWayne]

Better get some glasses for the Mark IV. The topic of this thread is a laser's range as a weapon

 

[nyrath]

A spacecraft flying not far out of Earth's orbit has a large laser weapon installed for defense against attacking ships. A ship comes in to attack and our spacecraft fires her laser at it. The laser beam misses and heads off in the direction of Mars.

My question is: would the laser strike Mars, or could its power or potency diminish enough to be ineffectual by the time it reaches its destination. I would think that a sufficiently powerful laser (like one that would badly damage a large spaceship) would continue all the way to Mars. This, as I see it, would make laser's as ship's weapons not that realistic.

It will probably be ineffectual by the time it reached Mars. Unless your ship had a laser weapon similar in size to the one on the Death Star.
http://www.projectrho.com/rocket/rocket3x.html#laser

Laser light is not subject to the inverse square law as is conventional light. However, it is subject to diffraction. This will spread out the beam, increasing what is called the "spot size." In other words it will do the opposite of what a magnifying glass does to sunlight when a naughty child is incinerating ants.

RT = 0.61 * D * L / RL
where:
RT = beam radius at target (m)
D = distance from laser emitter to target (m)
L = wavelength of laser beam (m)
RL = radius of laser lens or reflector (m)

In this case D will be the average distance between Earth and Mars, about 2 x 10^11 meters.
For L, let's try far ultraviolet, just short of x-rays, about 2 x 10^-7 meters. Note the minus sign.
For RL, let's start with 1 meter radius just to see what happens.

RT = 0.61 * D * L / RL
RT = 0.61 * 2 x 10^11 * 2 x 10^-7 / 1
RT = 24,400 meters radius = about 15 mile radius

How intense will this be? Keep in mind that the energy in the beam will be the same, it is just that what might be a damaging amount of energy focused in a beam 1 meter in radius could prove to be utterly harmless when spread out into a 15 mile radius beam.

First figure the divergence angle:
θ = 1.22 L/RL
where:
θ = beam divergence angle (radians)
L = wavelength of laser beam (m)
RL = radius of laser lens or reflector (m)

θ = 1.22 L/RL
θ = 1.22 2 x 10^-7/1
θ = 0.000000244 radians

Now we can figure out how many megawats per square meter the beam at Mars will be
BPT = BP/(π * (D * tan(θ/2))^2)
where:
BPT = Beam intensity at target (megawatts per square meter)
BP = Beam Power at laser aperture (megawatts)
D = range to target (meters)
θ = Theta = Beam divergence angle (radians or degrees depending on your Tan() function)
π = Pi = 3.14159...

Say that the Beam Power BP is 1,000 megawatts or 1 gigawatt
BPT = BP/(π * (D * tan(θ/2))^2)
BPT = 1000/(π * (2 x 10^11 * tan(0.000000244/2))^2)
BPT = 0.00056 megawatts per square meter.

For comparison purposes, the average beam intensity of sunlight on your skin is about 0.0014 megawatts per square meter. This means our ravening ultraviolet 1,000 megawatt death beam will be a tad less than one half the strength of sunlight on your skin, by the time the beam reaches Mars.

You can make the beam stronger if you increase RL, the beam radius at the laser gun, but this gets to be unwieldy. It will be very difficult to make L the laser wavelength much smaller than it is. X-ray lasers are quite difficult to construct. See the link above for details.

 

[DrRocket]

Laser light is not subject to the inverse square law as is conventional light. However, it is subject to diffraction. This will spread out the beam, increasing what is called the "spot size." In other words it will do the opposite of what a magnifying glass does to sunlight when a naughty child is incinerating ants.

RT = 0.61 * D * L / RL
where:
RT = beam radius at target (m)
D = distance from laser emitter to target (m)
L = wavelength of laser beam (m)
RL = radius of laser lens or reflector (m)

Laser light is most certainly subject to the inverse square law, at least in the far field, as is any other light. In fact yourequations prove it. There is nothing magic about the inverse square law, and it is basically a result of geometry, and the simple fact that the surface area of a sphere is proportional to the radius squared.

The radius of the spot is given by your first equation which shows that it is proportional to distance D. Intensity of the spot is proportional to the area of the spot which is just pi*RT^2, so the power density, PD is proportional to the square of the radius RT which is inversely proportional to D and hence PD is inverselyh proportional to the square of D, which is the inverse square law.

The only way that a laser can fail to obey the inverse square law is if it is perfectly collumnated with zero dispersion angle (I am assuming uniform power distribution over the spot, which is a reasonable approximation at least in the far field).

 

[nyrath]

Well, a theoretically perfect laser would not obey the inverse square law, since all the photons are moving parallel to each other. This is because a laser is not a point source.

In practice, there ain't no such thing as a perfect laser. The situation can be approximated by using the inverse square law, but using a fudge factor that the virtual point source of the laser is actually a long long distance behind the actual location of the laser emitter.

http://sci.tech-archive.net/Archive/sci ... 00172.html

I was assuming a perfect laser, but with the limit imposed by diffraction.