Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

I am referring to the use of specific particle types such as an antiproton beam, positron beam, meson beam or muon beam for example in the likes of shows like star trek. I was curious if a beam of a certain particle would produce specific effects or is this purely wishful thinking.

I am by no means a physicist so straightforward answers would be great if possible. If the answer could describe what effect each particle would have on materials, which particles are of particular use and which ones are impractical. Would it matter if the particle is normal or antimatter?

I understand there is a lot of variables and factors like the way a particle decays, the particle half life and velocity affects its range distance, the energy of each particle, the materials the particles interact with, etc etc so any input is appreciated.

To summarize, i am asking in terms of the realistic attribution of weapon effects to certain particle types and also non-weapon effects.

share|improve this question
    
Would skeptics.stackexchange.com be a better home for this question? –  Qmechanic May 3 '13 at 13:04
1  
Of course, the statement is nearly tautalogous--different particle beams will affect targets differently--that's how we know that they're different particles, after all. –  Jerry Schirmer May 3 '13 at 13:32
    
The most important factor is COST. If you direct a beam of rather energetic particles (apart from neutrinos, that is) at somebody, it's going to hurt whatever the particles are. –  Deer Hunter May 3 '13 at 13:44
1  
Anyway, in real life certain specialized types of particle beams are used to treat cancer. This is called radiation therapy. (I should know - I'm married to a radiation therapist.) You can look into the medical literature to see what sort of side effects they get - things like "sun"burn in some cases. These are treatments that are tailored to treat cancer cells and spare normal tissue as much as possible. With a weaponized beam you could do real damage. The issue is cost and portability. LINACS cost millions and can't be moved once they are installed. –  Michael Brown May 3 '13 at 13:51
1  
Positrons or other antimatter are potentially more efficient than other particle beams at delivering all of their energy to the target. Compared to the kinetic energy we could deliver with a high-velocity metal projectile, particle beams would lose every time. –  Brandon Enright May 3 '13 at 16:03

1 Answer 1

Charged particles can't be used in air. In outer space, they can be deflected by electric or magnetic fields. A collimated beam will also become defocused by ambient fields over a sufficiently long distance -- and the distances are typically very long in outer space. If you make a beam of, say, negatively charged particles, then conservation of charge says there are also some positively charged particles -- what do you do with them? Charged particles are not very penetrating, so it's easy to shield against them. For example, MeV electrons stop in a piece of cardboard.

A general problem with any particle beam weapon is waste heat. For instance, at a heavy-ion accelerator where I used to work, the beam would typically be about a watt, whereas the accelerator probably used many kilowatts. I.e., accelerators tend to be the most fantastically inefficient devices ever created. In the classic battling-spaceships scenario, the efficiency of the ray-gun would have to be incredibly high, or the gun would just destroy its own ship with waste heat. (This issue also applies to relativistic propulsion of a ship.)

Antimatter would annihilate with matter in the target, producing a devastating explosion if there was any significant amount of it. Charged beams of antimatter are relatively easy to produce, but suffer from the same problems as other charged-particle beams. Neutral antimatter is extremely hard to produce; nobody has ever made more than a tiny number of antihydrogen atoms. If you could produce it, you wouldn't be able to accelerate it with electromagnetic fields.

In real life, satellites and other space vehicles are extremely flimsy and vulnerable things, and the kinetic energies involved are very high. It's very difficult, for example, to keep the ISS from being destroyed by stray space junk. This is one of the reasons that the type of space-based weapons envisioned in SDI (Reagan's "Star Wars" program) are fundamentally a pretty stupid idea. It's really easy to knock them out by hitting them with a small bullet moving at high speed. Countermeasures also tend to be much cheaper than the weapons themselves.

[EDIT] Fixed my totally incorrect analysis of antimatter.

share|improve this answer
1  
Charged particle beams can propagate through non-trivial distances in the atmosphere by a combination of self-focusing and holeboring. I think that 20 meters were demonstrated and kilometers were hoped for (beam instabilities are the main problem). A very good technical summary of the "state of the art" in "directed energy weapons" during the 80s can be found in the Report to The American Physical Society of the study group on science and technology of directed energy weapons. –  mmc May 4 '13 at 3:23
    
thanks for the input, all the comments and answers have gave me lot to think about!! –  MICHAEL TAYLOR May 4 '13 at 23:24
    
@mmc: Thanks, the RMP article is a great resource, although 25 years out of date. It's not paywalled, and there is a good executive summary near the beginning. –  Ben Crowell May 5 '13 at 15:10

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.