Antimatter Thrusters?

[kokomo0020]

Antimatter is everything matter is not: the protons are negative, the electrons are positive, and the neutrons are neutral. Physically, there is not much difference between matter and antimatter, the seem to follow the same basic principles as matter. But, although they act alike, when in the presence of one another, they annihalate each other and release an amazing amount of energy.

 

This antimatter energy is not hard to come by. Simply create antimatter in an accelerator, present it to matter, and it creates useable energy. Engineers everywhere are searching for new, efficient ways to get to planet Mars. People have tried combustion, people have tried nuclear. Why not antimatter? The energy is so easy to create, and it is almost impossible to run out of fuel because matter is everywhere! Noone has yet to attempt or even theorize the use of antimatter thrusters, but prove me if I'm wrong.

Edited September 11, 2011 by kokomo0020

[mississippichem]

As of current we can only produce antimatter at a very slow rate in a very slow, expensive, and inefficient process. To isolate and contain even a kilogram of antimatter would be an enormous victory at this point .

[swansont]

This antimatter energy is not hard to come by. Simply create antimatter in an accelerator, present it to matter, and it creates useable energy.

 

Macroscopic amounts are hard to come by, as mississippichem has noted. It takes a lot more energy to create the antimatter than you get back because the process is inefficient.

 

But let's say you had a jar of positrons and could store them for an indefinite period of time. You have some annihilate with electrons, giving you two 511 keV photons, traveling in opposite directions. How would you convert this into thrust?

[ajb]

You have some annihilate with electrons, giving you two 511 keV photons, traveling in opposite directions. How would you convert this into thrust?

 

Could one use some arrangement of mirrors and exploit the radiation pressure?

[insane_alien]

I imagine that you'd likely want to have the engine flooded by matter thats good at absorbing gamma rays to then be heat up and expelled from the reaction chamber at high speed.

 

the amount of shielding required would be prohibitive however.

[Mr Skeptic]

In theory, antimatter thrusters are the very best that is theoretically available, if you mean to use the annihilation photons as thrust and want the very best weight to thrust ratio. Of course, in practice we could choose between enough antimatter to run a car a few miles and enough energy to run our civilization for a year. If we could get a way to generate antimatter at 0.01% efficiency or better, then it might be worthwhile as an energy source for a thruster. Even so, we'd probably use the antimatter as a heat source (or energy source for an ion engine) rather than use the photons, or maybe to ignite a miniature fission bomb, as the efficiency (per unit energy, rather than weight) would be much better. Of course, we'd never be able to do that with any current method of making antimatter. Never mind the possibility of an epic explosion, and the amount of shielding that would be required to protect from the gamma rays.

 

kokomomo0020, do you realize that to use antimatter as energy you lose your antimatter? You don't annihilate the matter and keep the antimatter. Unless you're making a gigantic ship, you're carrying both your matter and antimatter with you as it will be easier to do that then to harvest matter.

[swansont]

Could one use some arrangement of mirrors and exploit the radiation pressure?

 

x-ray mirrors are really inefficient, as is photon thrust. The one advantage photon thrust has is that you don't have to carry propellant.