Hi guys,
I've been thinking - the point of the filament heater is to enable the release electrons from the cathode. Would it be possible to use a cathode that uses photoelectric release of electrons? Basically instead of heating a bit of metal to hundreds of deg.C, you could shine an LED (or other light source) on to a coated cathode and use such a tube for the same purposes you'd use a thermionic one, if obviously at much lower powers.
It would draw much less power, start up instantly, have a longer life span. The downsides are obvious - much less power.
Basically I've been thinking about how to make a very low power x ray source that could be used inside of a detector, and this came up as an idea - no filament, just the accelerating voltage, which would draw pretty much no current.
I know there are phototubes, PMTs, etc. but they are used to actually measure light and not use the photoelectric electrons to do signal amplification and other tube functions.
So, could such a tube work?
Thanks ,
David