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I am trying to get a better handle on how the EBPVD machine works in the lab I am working in. I understand that it produces an electron beam with a tungsten filament and that beam is then directed toward a crucible holding silver or aluminum using a magnetic field. All of that I understand, basically. I am an Electrical Engineer by training, so the process in which an electron beam can be created by heating a tungsten coil is escaping me at the moment.

My best guess for the process here is that by heating the coil the electrons are excited enough to break loose from the tungsten atom and become free electrons where they are directed into a beam structure by the magnetic field. Again, I am not, in any way, trained in physics beyond basic mechanics and a couple of electromagnetism classes, so please excuse my generalities with the terms here, I am just trying to understand the equipment that I am working with a little better.

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  • $\begingroup$ Kids these days -- they never had to wait for a radio to warm up! (and they don't use tube audio amps either!) $\endgroup$ – Carl Witthoft Dec 1 '15 at 15:25
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My best guess for the process here is that by heating the coil the electrons are excited enough to break loose from the tungsten atom and become free electrons where they are directed into a beam structure by the magnetic field.

Yeah, that's (almost) it. You detach the electrons from the cathode by thermal excitation, and then you remove them with an electric (not magnetic!) field. The process is known as thermionic emission - the Wikipedia page is probably a better place to fill you in on the details.

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  • $\begingroup$ That is literally, exactly what I was looking for. Thank you for the information. $\endgroup$ – christopherbrown0317 Dec 1 '15 at 13:40

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