Eisboch wrote:

It used to be referred to as "emission". Same thing occurs in vacuum
tubes.

It's called 'thermionic emission', since it is the heating of the cathode
causes the electrons to be released from same. It should be noted, however,
that there is no need to create a directed flow from one electrode to
another for there to be emission (a hot soldering iron is a thermionic
emitter). Indeed, without an anode, the emitted electrons congregate within
the glass envelope and create what is called a 'space charge'. To accurately
describe the *transfer* of electrons from one electrode to another, the term
'emission' is insufficient.


To further confuse, I recall the correct terminology as being
"emission current".

I see no reason to be confused by referring to it as current. If one
connects an ammeter between the anode and the +HT supply, or between the
cathode and ground, one will read a current. If there is current at one side
of the valve, and current at the other, then surely there is current within
it? If the flow of electrons from cathode to anode is not current, then what
is it?


--
Wally
www.artbywally.com
www.wally.myby.co.uk