Lecture 12 -Ambipolar diffusion, Paschen's law, breakdown voltage, secondary electrons

[@b1zzler]

Is the ambipolar diffusion effect caused by special relativity? I don't really understand the vector calculus behind flux and diffusion, so the only thing I can think of that intuitively reconciles the DC bias effect with quasi-neutrality is a spatial contraction of fast-moving electrons in the plasma relative to slow-moving electrons in the solids.

[@rahatahmed9678]

Thank u so much, superb explanations

[@usmanawan4541]

i want proof of diffusion equation plz

[@rudresh_official]

Thanks

[@moaaz2928]

Nice Video, But I have a question, we know that A B are constants we can get it from the literature but how can i calculate Y ؟

[@usyd-seniorplasmaphysicsle6653]

Gamma (the secondary electron emission coefficient) has to be measured. There is literature that give gammas for various metals.

[@moaaz2928]

Thanks for answering, I have a wire to cylinder Corona reactor ... Can I used this relation for calculating the breakdown voltage for my N2 and H2 mixture؟ My both electrodes are Stainless steel

[@usyd-seniorplasmaphysicsle6653]

The breakdown voltage equation assumed a uniform electric field between two electrodes. A wire to a cylinder has a non-uniform electric field, which is highest at the wire. In that situation, the breakdown voltages are usually smaller than predicted by the equation. Also, available secondary electron emission coefficients in the literature assume the electrodes are clean and not oxidized. Chances are you don't have that. So at best the equation can give you a ball park idea of what the breakdown voltage is. It is something you need to experiment with for your particular set-up in order to determine what the breakdown voltage is.

[@stevensesselmann9281]

Thanks Joe, that was helpful.. ;)