Bayard Alpert Gauge X-ray limit

[JBC]

When the cathode emits electrons which are accelerated towards the grid, usually on its way it will ionise a molecule in the vacuum. However at a certain low pressure there are too few molecules and therefore the electron will hit the grid and emit an x-ray. My question is, wouldn't electrons create x rays even when not at the x ray limit?

 

[AndyW]

Thank you for your question. I can provide some information about the process of electron emission and X-ray production in a cathode.

Firstly, let's understand the basic principle of electron emission in a cathode. When a high voltage is applied to the cathode, it creates a strong electric field that pulls electrons out of the cathode surface. These electrons are then accelerated towards the grid, which is at a higher potential. As the electrons travel towards the grid, they collide with gas molecules in the vacuum chamber. This collision can cause the gas molecules to lose an electron, resulting in ionization.

Now, let's address your question about X-ray production at low pressures. As you correctly mentioned, at low pressures, there are fewer gas molecules for the electrons to collide with. This means that there is a higher chance of the electrons reaching the grid without any collisions. However, even at low pressures, there are still some gas molecules present in the vacuum chamber. When an electron collides with a gas molecule, it can still cause ionization and produce X-rays.

So, to answer your question, yes, electrons can create X-rays even when not at the X-ray limit. However, the probability of X-ray production is higher at the X-ray limit, as there are more gas molecules for the electrons to collide with.

I hope this helps to clarify your doubts. If you have any further questions, please feel free to ask. Thank you.