Re: Is there a way to produce a blue electron beam

In answer to your direct question, no, you cannot make a blue electron beam. Electrons have no inherent color. Color is a characteristic of photons (light). Where you have atoms or molecules emitting certain wavelengths of light, you can also kind of associate a color with them. (For instance, the element neon tends to emit a light of light in the red, yellow and orange parts of the visible spectrum, leading to its characteristic orangey color.) Electrons have no preferred energies by themselves, so they do not have a color₁.

But there is good news! If instead of electron beams (which would make your light saber highly charged, a very dangerous thing), you could fill the magnetic bottle with a plasma. A hot plasma would probably make a very effective cutting tool². You can heat the gas up by running the electrons through it. (This is how neon lights basically work.) Also, the magnetic fields would repel each other, so two light sabers wouldn't be able to cross³. And you could make the plasma glow any color you want by loading it with the right elements. (Mercury glows a kind of bluish color in gas discharge tubes that are used in classroom demonstrations, but I can't recall how ionized it is in that state.)

That's the good news. Here is the bad news: you probably can't make such creatures at home. For one thing, it'll take a lot of energy to make a strong enough magnetic bottle. Worse, it's difficult for me to see how you can make the right kind of bottle when you only have one end of the light saber. (Also, pretty though it may be, avoid mercury! As a gas, the stuff is extremely toxic. Not something to be messing about with.) Also, such a light saber would be pretty dangerous to handle.

Personally, I stick with real sabers for fencing with other people. Admittedly, they don't make that cool sound and they cannot slice through metal (something I've often wanted to do when cars try to run me over). But they can draw sparks off of your mask and people seldom get badly hurt with them. I keep light sabers on my list of things to fantasize about owning, but never will do so.

You can have some fun playing with the colors of a few gases at http://phys.educ.ksu.edu/vqm/html/emission.html. A search with Google on the terms "gas discharge tube colors" will also bring up many more, similar hits.

¹ — Personally, I always visualize electrons as being red. But I also think of them as feminine. I hasten to add that the universe is not obliged to make my views a reality and, as far as I know, neither view is remotely accurate.

² — Provided that the thing you want cut doesn't have a strong magnetic field around it. A magnetic field would make a really good shield in this case. Hm, if light sabers ever became popular, I can see a good way to make a fortune.

³ — Except if you crossed the sabers with the magnetic fields so that the field lines were just oppositely oriented. In that case, you might get what we call reconnection and your sabers would sort of fuse together. This is always a horrifically embarassing thing to happen to a young Jedi, especially on a date.