Corona discharge the electron-liberation is a high-energy photon from an atom within the plasma body relaxing after excitation from an earlier collision. The use of ionized neutral gas as a source of ionization is further diminished in a negative corona by the high-concentration of positive ions clustering around the curved electrode. Under other conditions, the collision of the positive species with the curved electrode can also cause electron liberation. The difference, then, between positive and negative coronas, in the matter of the generation of secondary electron avalanches, is that in a positive corona they are generated by the gas surrounding the plasma
Positive and negative parts be expressed in terms of "f" and "f" as Also note that Using these two equations one may express the positive and negative parts as Another representation, using the Iverson bracket is One may define the positive and negative part of any function with values in a linearly ordered group. Given a measurable space ("X",Σ), an extended real-valued function "f" is measurable if and only if its positive and negative parts are. Therefore, if such a function "f" is measurable, so is its absolute value |"f"|, being the sum of two measurable functions. The converse, though, does not necessarily hold: