On Wednesday, April 25, 2018 at 12:21:29 PM UTC-4, wrote:

"Nuke magnetrons use thoriated tungsten bright emitters. "

AHA, so that filament is already burning pretty hot then right ? I see.

No, they don't. The emitter is a solid cylinder of Barium Oxide with a (usually) copper filament inside it. There are other Barium salts used as well, but no Thorium.

"Bright Emitter" magnetrons are used mostly for industrial heating applications - not hardly in what you have in your kitchen - even an old Amana, or Litton. The cutting-edge of magnetrons is in making more compact and shorter-wave (high-resolution) radars. Neat stuff going on there.

Peter Wieck
Melrose Park, PA