cathode ray

[the guy]

if one where to (hypothetically) take a cathode ray tube from a television set, remove the front, put it in the necessary vacuum etc etc and put a piece of metal in front of it, would this kind of cathode ray have the power to melt the metal, in the same way the electron beam welders do?

[John Cuthber]

Only if it was a very small bit of metal, or one that was very easy to melt.

Having said that, because the metal is in a vacuum there's no way for it to lose heat by convection or conduction (throughh the vacuum) so it may take less heat to melt than you would normally expect.

[swansont]

The EBW power supply pulls a low current (usually less than 1 A), but provides a voltage as high as 60 kV in low-voltage machines, or 200 kV in high-voltage machines.

 

http://en.wikipedia.org/wiki/Electron_beam_welding#Equipment

 

TVs are generally lower energy, and probably don't focus the spot to as small of an area.