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A laser photon hits a H2 or He Ion directly from behind .The H2 or He ion accelerates X amount.Another photon hits the same ion directly from behind, and it accelerates X amount again. This happens at a billion to one ratio. How much acceleration will this give to a spacecraft?
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This depends on the wavelength of the light, and several other factors. And answer is, not very much, since the hydrogen (or other atom) will usually dissapate the extra energy through some means other than conversion to momentum, with hydrogen molecules this could be an increase in bond vibration or gyration. This is not a simple question to answer quantitatively, but it is easy to answer qualitatively... It would produce very little linear acceleration if any, and what it would make would be converted to random thermal motion in short order at any useful gas pressure.
Again, light does not obey the standard "billiard ball" physics collision mathematics.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
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If the gas was confined in a tube, and the laser cross section was almost equal to the inside diameter of the tube then the gas would always be struck from behind by the laser photons.
Do to the added heat the pressure would rise plus the ions would be constanlty bombarded from behind while in this tube. If each ion were struck one billion times how fast would they exit the tube?
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Ions? What ions? You didnt' mention any ions... entirely ionized hydrogen would be impossible to hit with a laser, since it would be so small.
If you are talking molecules or free radical hydrogen... though the photons will impact from the same direction, that does not mean that the hydrogen will always move exactly that direction. If it is moving horizontally across the beams' path, it will be accelerated diagonally... now, then it will strike other molecules of hydrogen and also impart a horizontal componet to their motion, and this will happen again and again until the motion is completly random. Also, this speed will be a distribution, the molecules will all be moving different speeds, not just different directions.
The manifestation of this random motion is temperature, so what you have here is a laser-heated rocket engine, which will have a really really low efficency... Also, you have not specified any of the characteristics of your laser; what is its output? Wavelength? Dimensions of the tube?
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
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Say a 1 mw laser 1/4 inch diameter, very close wave length,50 foot long tube.The tube is the same charge as the ions. As the pressure rises the flow is out the back end of the spacecraft. However, as they start flowing in that direction the ions are bombarded by the photons from behind.
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But what is the wavelength? Close to what? Which absortion?
What you have described to me is basicly a pressure driven plasma engine. Hydrogen is pushed in by a pump, ionized slightly by electrostatics of the tube, and allowed to expand out the back which might be somewhat heated by the laser light.
I think it would work better if you flew up a giant latex balloon full of air and let the nozzle go "ptttbbbbfhhh"...
Again again again, laser light does not "collide" with particles persay, that is, its energy does not nessesarrily transfer to motion and infact rarely does. The efficency of such a system would be very small I would think, especially dealing with free atoms. There is no "bombarded" as you understand it.
Furthermore, this engine doesn't derrive any thrust from the ionization at all hardly, and would be wasted energy. Just use gas.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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What happens if you use just gas?
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About the same. It might get a little warmer if you tune your laser right. Gasses don't absorb light efficently enough to make a 50 foot long "chaimber" very effective.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Would a longer tube be better? Say a 100 foot long??
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You are talking about needing a very, very long tube to achieve any signifigant heating I think, and even if you did, you are still limited by the melting temperature of the tube, which is probably fairly low.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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So what you are saying is even though the tube cross section is filled by the 1 mw laser light, and the tube is filled with gas very few collisions would occur inside in the tube?
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Ion power is quiet slow for accelerations but there are other massive benefits, that is why Europes ESA, the people of NASA and the Russias have always said this might be the future of space transportation. [http://newsimg.bbc.co.uk/media/images/3 … a_i203.jpg]http://newsimg.bbc.co.uk/media....203.jpg
These trusters are a new science, we are only in the early stages just like when Von Braun invented the V2 rocket, the Ion engine and other types of power have a long way more to go, they are innovative form of propulsion and new power like ion thruster may be the key to opening space up for good. These new desings for Engine such as nuclear and solar sails might be the future. Right now people are keen on studying the Ion power. The Engines have several advantages, such as needing less propellant, having greater payload capacity and being capable of much more precise spacecraft pointing.
They deliver about ten times as much thrust per kilogram of propellant used than a chemical rocket, making them very 'fuel-efficient'. NASA have also been working on improvement and better design like DS1 Ion Thruster Compatibility. That engine provided the craft about 10 times the specific impulse of chemical propulsion. Another good example of promising design is the Europe SMART-1 , the ESA smart one seems like a good craft and will be scanning the moon for minerals, Helium 3 , Deuterium and other materials that might be used or benefical in a future lunar base.
[http://sci.esa.int/science-e/www/object … ctid=34800]http://sci.esa.int/science-e/www/object … ctid=34800
[http://www.space.com/scienceastronomy/s … 00816.html]http://www.space.com/science....16.html
'first steps are not for cheap, think about it...
did China build a great Wall in a day ?' ( Y L R newmars forum member )
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Alot of the photons would not hit any hydrogens and would just go sailing out the back of the tube. Gasses, hydrogen imparticularly, are pretty "thin" as far as matter goes.
Furthermore, for those photons that DO hit the hydrogen, since they don't carry that much energy it won't impart much energy to the gas, you must have a very large number of photons interacting to produce signifigant heating.
You are better off pumping liquified hydrogen into a running nuclear reactor or VASIMR and putting Xenon into an ion engine.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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I would like to add this laser-powerd hydrogen rocket is not an ion engine.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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For every photon that hits a h2 atom that H2 atom accelerates at 1meter per/sec. So for a 100 ft tube that atom is struck millions of times while it is inside it. Every atom is being struck MILLIONS of times since they are so much larger than the photons because the laser beam takes up the whole crossection of the tube.They could also be ions if you want for this type of engine. It would prevent tube wall erosion.
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Where do you get this 1m/sec figure? That sounds mighty fishy to me... And where do you get this figure that the average number of impacts over a 100ft length is in the millions?
And again, simply because a molecule is struck by a photon does not mean it will speed up, it may reradiate the energy, or just vibrate more, etc etc...
And lets say for a second that a molecule is hit many times by photons... the acceleration is still very small because the energy is not transferred to linear motion, the linear motion will become thermal motion with useful pressures, and because each photon has little energy each.
Using a laser as a means of inducing linear motion in gas molecules is a silly idea.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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It does both. If I told you where I got the information someone would kill me.
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For every photon that hits a h2 atom that H2 atom accelerates at 1meter per/sec. So for a 100 ft tube that atom is struck millions of times while it is inside it. Every atom is being struck MILLIONS of times since they are so much larger than the photons because the laser beam takes up the whole crossection of the tube.They could also be ions if you want for this type of engine. It would prevent tube wall erosion.
I'd like to see your calculations as to how you arrived at these figures, for they don't appear to me to add up. Do you suggest that from your calculatons the accelaration of H2 atoms is indefinite within the tube?
There was a young lady named Bright.
Whose speed was far faster than light;
She set out one day
in a relative way
And returned on the previous night.
--Arthur Buller--
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Someone would kill you? Uh huh... probably because you got your figures from a chapter of a text about how DeBroglie's wavelength and the "standing wave" quantum nature of matter permits the creation of polarized gravity, limitless free energy, and of course provides mathematic proof of God because of the behavior or quasars?
Oh and lest I forget, "digital genetic" electrogravitics!
The fact that the distance unit of one meter is originally based on the circumferance of the Earth somehow coincides how basic particles interact? I doubt that.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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Bwhaaaaa!!! Bwhaaaaa!!!! Bwhaaaaa!!!! To think photons don't accelerate atoms or ions is foolish!! Bwhaaaaa!!!!!Bwhaaaaaa!!!!...
The sun does it every day,and the amount of atoms is very small which proves my theory that every one of them are being bombarded so much so they reach escape velocities and well beyond.
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I don't think it can accelerate hydrogen ions, which have a diameter less than the amplitude of the light wave if memory serves, which is why you can't use an optical microscope on the subatomic scale... And since these are the ones being emitted by the Sun predominantly...
The amount of ions the sun produces is mindboggling, the sun is really big, and these are produced at such high energies that reaching the Sun's modest escape velocity is not that hard, not because they are being accelerated by photons. Particle accelerators can manage it without breaking a sweat, no laser involved.
Next you'll say that your "self thinking interface" told you that i'm full of crap, i'm sure, just before the Freemason assassins hunt you down...
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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The sun is a different story I am talking about Earths atmosphere. Although, the same is happening at the sun. The amout of photons a laser emits is mindboggling that is why the collisions are so frequent.Remember the laser is the full width of the crosssection and the atoms are in the lasers beam at times when inside the tube. Nothing could escape without being hit except for other photons. The atoms are millions of times bigger than the photons.
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Then why were you talking about the sun? Okay... so, now you are talking about an onboard laser powerd rocket that gets its propellant mass from ambient air? The tiny thrust produced won't even get you off the ground.
There are a large amount of photons produced by a laser, however the energy of each of these is quite small, and since they are traveling so fast they can sail right around the slow-moving atoms... think of an airplane propeller, if you slowly try to stick somthing into the whirling blades, it will get chopped up, but since the photons are moving extremely fast and the atoms are not, the propeller might as well not be turning at all, in which case you can easily avoid the blades.
Atoms also are not that big compared to the amplitude of light waves, atoms are really small, and hydrogen ions are millions or billions times smaller than atoms. No, the light beam can easily sail right around ions, and not hit that many atoms either, even if you do have the proper absortion wavelength.
I would be willing to say that its a statistical possibility that some atoms CAN escape this short pipe without being hit by any photons.
Nor have you given any background for your figures about how light energy magicly convertes to linear velocity of gas atoms nor have you listed what the wavelength of your laser is, which makes any sort of quantitative aproach useless.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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If you are so confident about your theory of the planes propeller then swing your hand in it while it is at full speed. See how long it will last you may get lucky.
I would be willing to say that its a statistical possibility that some atoms CAN escape this short pipe without being hit by any photons.
Not one will escape from being hit because it would not move untill it was hit.
Nor have you given any background for your figures about how light energy magicly convertes to linear velocity of gas atoms nor have you listed what the wavelength of your laser is, which makes any sort of quantitative aproach useless.
It is well documented what happens with linear collisions between atoms, ions and photons. If the photons had no mass then a collision would not occur nor would there be any kinetics involved or heat generated.
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Its all relative... if you are traveling at the speed of light, then anything not moving a signifigant percentage of the speed of light will apear to be stationary. Atoms and molecules only travel in the thousands of meters per second, nowhere NEAR the speed of light.
And all atoms and molecules move, because they all have thermal energy, which you cannot entirely eliminate no matter how hard you try (Zero Point Field would get involved). They would very much move out the back of the tube naturally due to this energy, laser or no.
The collision between classical particles is well known, but the photon does not behave according to these rules. If you have a book or somthing that says that, then the author is either an idiot or a liar. Photons can impart momentum, but not by the method that you understand them to.
Although photons don't have any rest mass, they still carry energy, because the ARE energy in a neat bundle, and not a chunk of matter persay, and they very much can collide with objects with similar or greater size than their amplitude.
The kenetics that you are using are classical Newtonian ones, which just don't apply to photons because they are not really made of matter. They generate "heat" by imparting motion to molecules and atoms via absorptive excitation of their electrons, not a kenetic collision with them.
[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]
[i]The glass is at 50% of capacity[/i]
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