Free charge carriers appeared in the air space between the capacitor disks. Their appearance is due to the fact that during the collision, part of the neutral atoms or molecules turns into ions, i.e., the gas is ionized. In this case, positive ions and free electrons are formed. If some of the free electrons are attached to atoms or molecules, then negative ions arise. The ordered movement of charged particles in an electric field between capacitor disks is an electric current in a gas.
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