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Spark in a spark generator

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This is the spark in a spark gap transmitter, a transmitter in the early of radio is discovered, or maybe including the Hertz's experiment itself. This is also we may see in a spark plug of our car. The similar thing we see with lightning in nature. The interesting thing for me, and it is my question, why does the spark is not jump in a straight way, and what cause it make certain random path? Once I read about ionization of air. If it is the case, then what is in "that" air so the spark doesn't not jump in a straight way?

Qmechanic
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AirCraft Lover
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1 Answers1

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In any given brief instant of time, the density of air molecules on microscopic length scales undergoes random fluctuations about the mean value which hence furnish local fluctuations in how easily charge buildups can reach the breakdown values necessary to allow the spark discharge to propagate.

Furthermore, those breakdown mechanisms depend strongly upon the presence of photons (typically UV) within the spark gap which cause random ionization events to occur as those photons are themselves randomly distributed in space and time.

These effects mean that spark propagation through air will follow unpredictable pathways. it also means that subsequent sparks occuring close in time tend to follow the paths of previous sparks, as the deionization processes that extinguish the earlier spark take a finite amount of time to run to completion- and the earlier spark channel provides a low-resistance path for a later spark discharge.

niels nielsen
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