Would it be possible to opperate an ion engine with other gasses apart from the noble gases currently in use? Lets say for example hydrogen? and if so,what benefits dissadvantages do different gasses represent?
2006-09-28 06:18:36 · 5 answers · asked by kent_thoresen 2 in Science & Mathematics ➔ Astronomy & Space
Some ion engines actually run off of solid fuels.
A PPT, or pulsed plasma thruster, uses solid Teflon (yes, the stuff on cooking pans) and ionizes a sheet of the fuel. Electromagnetic physics controls the flow out of the engine and supplies the energy for thrust.
Gases that are easy to ionize and non-corrosive are the best for electric propulsion. Sure, you can use any gas as a propellant. However, ionization energy and molecular weight play a huge role in the performance of the engine.
2006-09-28 06:58:20 · answer #1 · answered by AresIV 4 · 0⤊ 0⤋
A variation on the Ion engine called the Plasma rocket (VASMIR) can actually use a wide array of gasses. The plasma rocket has much better thrust capabilities (if enough electricity is supplied).
One benefit mentioned to me by the inventor (Dr. Frank Chang-Diaz) is that hydrogen is a good insulator against radiation. Placing the fuel tank around the space craft could help to protect the astronauts from some of the radiation.
I believe they've also used cesium atoms as well (and many of the noble gasses).
What's exciting about using cesium atoms is that another type of engine has been proposed that is rather unusual. Using a quantum phenomenon known as entanglement, pairs of cesium atoms can be entangled such that one half of the set is immediately effected by whatever happens the other half.
In this proposed engine, the fuel (cesium atoms for instance) could be entangled and split so that half of the set is on a probe and the other half is hear on Earth. Then the atoms on Earth would be "excited" by using local energy (like a hydro-electic dam). Then the space probes entangled pair would also become excited and thrown out of the craft. This would mean that the energy to run the engine would not be on the craft, which means less mass.
2006-09-28 10:42:29 · answer #2 · answered by Doob_age 3 · 0⤊ 0⤋
In principal, sure. I believe the choice is mostly, if not strictly, based on the mass of the ion. For example, Hydrogen is atomic mass 1, whereas Xenon is 131.
Consider this, if you're standing on a rowboat with no oars, to get moving which would be more effective, throwing a ball of paper for the rear of the boat, or a bowling ball?
The bowling ball will take more effort on your part, but get the boat moving faster.
Another issue that may come into play, by the way, is ionization potential. That is, how much Voltage is required to ionize the gas.
2006-09-28 06:34:25 · answer #3 · answered by entropy 3 · 0⤊ 0⤋
Hydrogen has a lower molecular weight, and thus would provide less force. Also they are easy to ionize - compared to say molecular oxygen, and won't corrode you engine.
But I'm no expert on these. Wrote a paper on potentially using helicon waves as an efficient ionization method for ion propulsion many many years ago.
2006-09-28 06:23:57 · answer #4 · answered by Dome Slug 3 · 0⤊ 0⤋
Some more or less massive material must be present for thrust. If you could figure out how to create a powder of ionizable solid fine enough it could probably be used, but a fine enough powder would be, essentially a gas. Alpha and beta particles are useable, theoretically, as they have mass. But some massive material has to be present. Now, if you had a light beam sufficiently powerful it could be used, and so far (as far as I know) light photons have not been found to contain mass, only inertia.
2006-09-28 06:24:02 · answer #5 · answered by David A 5 · 0⤊ 0⤋