As we can see that for some instance air can tolerate the potential difference between two points without any high leakage current and when this potential difference between the two points becomes too large then the arcing might happen, then what is that thing which provides the ionization energy to the atoms of the air so that the electrons gets ionized from the atomic shell of the air particle?. what is the reason behind that this phenomenon tends to happen? So that it can make the air conductive and the arcing happens.
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$\begingroup$ Have you made any effort to look this up on line? $\endgroup$– Bob DCommented Jan 13, 2022 at 8:42
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$\begingroup$ I looked up for this online but still not getting the correct reason as you can see that two people already answered to this post and both of them has given the different answers! That's the reason I'm trying to find out the actual answer that would satisfy me correctly! $\endgroup$– Tejas DahakeCommented Jan 13, 2022 at 8:53
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$\begingroup$ There are two different mechanisms of air ionization by electric field. Direct ionization of molecules takes place in very strong electric fields. The avalanche mechanism works in weaker electric fields, so arc in air is typically caused by the avalanche mechanism. $\endgroup$– akhmeteliCommented Jan 13, 2022 at 9:12
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$\begingroup$ @BobD Researching on this for almost 4 days but the reason I'm thinking seems different from the others got tons of answer and still the people are lacking something according to me in their answers. I'm not here just to get your answers, I want number of approaches to get out of this $\endgroup$– Tejas DahakeCommented Jan 13, 2022 at 9:12
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$\begingroup$ Just an additional comment: the value of breakdown electric field at ground pressure is $\sim 32$ kV/cm which is obtained by equating the ionization and two-body attachment (to molecular oxygen) frequencies, i.e., $\nu_{\rm i}=\nu_{\rm a}$. $\endgroup$– NewbieCommented Jan 13, 2022 at 12:29
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2 Answers
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Initial electrons in air (say, caused by cosmic rays) get accelerated in the electric field to energies sufficient to ionize atoms, and you have an avalanche.
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Cosmic rays, or other background radioactive sources, collide with the air molecules within the potential difference and electrons are removed from these molecules leaving free electrons that are then accelerated colliding with other molecules. This results in further ionization of air molecules. This means there are more electrons, which allows for the formation of a current (the positively charged ions left around can also form part of the current).
