In the latest BA newsletter, the BA claimed the ion drive worked with "powerful magnets". This made me wonder and I checked the technical info on the page that was linked in this post.

What I found was (quoted from HERE):

Now I'm even more confused.

Am I too stupid or is this thing at best overly simplified?

Now, apart from a cathode that apparently "creates" electrons (Hey, I want to be able to do this too! Then my energy bill wouldn't be such a problem anymore...),

the "electrons collide with the incoming xenon gas and form Xenon ions, positively charged particles and more electrons" ???

Is there some sort of small CERN in this device? Or can anyone explain to me (or give me a better link) how this is supposed to work? :-k


jokergirl

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"Half of what I say is meaningless, but I say it so that the other half may reach you."

I'll give it a try. In a sense it is a small partical collider. The cathode is similar to the cathode in your T.V. A current is run through the cathode causing it to be heated . The electrons "boil off" and are accelerated by a magnetic field and then collided with the xenon gas. The collision causes one or more of the xenon atom's electrons to be knocked out of its orbit leaving the xenon atom with a net positive charge. The electrons are not "created" in the sense of from nothing. They come from the cathode and from the xenon atoms themselves. Since the xenon atoms now have a positive charge, an electric field can be used to accelerate them.

I'm sure others can give more details of how the total process works.

Last time I read about it, you couldn't accelerate electrons with a magnetic field; you rather needed a (static) electric field. =^.^=

I guess it's safe to assume that "positively charged particles" are the same particles as the "xenon ions", but how does the process of knocking off electrons work? Doesn't that require a very high energy state? Are the electrons accelerated so much as to give that high energy state in a collision?

It seems to me there must be lots of energy put into the system somewhere; where does that come from? From solar panels or a fusion plant, or do the ion drive leave a lot of leftover energy? (The pages say solar panels, but it doesn't seem to me that they could give the needed energy alone.)

The electrons are accelerated by an electric field, much the same way that electrons are accelerated in your television's cathode ray tube. The magnetic field mentioned in the article may be for some kind of temporary containment, but I'm not sure.

Yes. The positively charge particles are the xenon ions. Xenon is a fairly heavy element and its outer electrons are weakly bound. The electrons from the cathode collide with the xenon atoms at kick out 1 or more of those weakly bound electrons, giving the xenon atom a net positive charge. The xenon ion can then be accelerated in an electric field and thrown out the back of the engine. I believe the electrons are ejected too so as not to create a net negative charge on the engine.

NASA's DS-1 probe got its power from solar panels. The engines built and tested so far are fairly small and not very powerful. Their big advantage is that they are efficient and can run continuously for long periods of time allowing velocity to slowly build up. For bigger engines and more thrust you'd probably have to go to some other type of power source.

Here is a link that does a better job of explaining the ion engine than I did. The sidebar specifically has some good information.

Tell that to the people who build cyclotrons. :P

Seriously, though, remember that the electrons aren't just sitting there -- they come off of the cathode with a little bit of initial speed. When a moving charged particle passes through a magnetic field, it accelerates in a direction perpendicular to the magnetic field lines. If the magnetic field is static, the charged particle will only whirl about in a little circle without going any faster, but if the magnetic field is changing, the charged particles moving through it can be accelerated in such a way thay they actually pick up speed.

But...but wait! That means...if I took some magnets and spun them around near a supply of electrons... I could make the electrons move! And if I could, say, trap the electrons in, say, a wire, then I could...

Holy cow! this could be BIG...

8)