How vacuum tube diode works?

Question

I am on journey to learn about world of electricity and all around it.

I have come to the topic of vacuum tube diodes and having hard time to understand what is going on.

I will start with how I understood it.

Basic concept is that we are having filament, and this filament gets heated up from first power supply. As I understood it, it is just conductor connected to power supply and current is flowing.

Filament emits the electrons into the vacuum.

Above filament there is a plate and that plate is connected to another power supplier and that creates electric charge, meaning plate will become positively charged.

Now electrons in vacuum gets attracted to the anode.

So far I think I understand this.

My problem comes when I try to visual how electron flow.

1. Does this mean when electrons from first power supplier goes to the filament, filament gets heated and that same electrons goes to the vacuum, after the vacuum he goes to anode and then back to the second power supplier ?

2. Does any electron get back to the first power supplier?

3. 

Answer 1

Your diagram has two loops around which current (electrons) can flow. One loop is from Battery 1, through the filament, and back to Battery 1. The other loop is from Battery 2, to the filament, through the vacuum, to the plate, and back to Battery 2.

Electrons have no identity. Every electron is indistinguishable from any other electron. Electrons have no memory. An electron in the filament does not know whether it came from Battery 1 or from Battery 2.

Since the filament is common to both loops, any given electron in the filament potentially could leave by joining the current in either of the two loops.