Effects of injection currents

The injection of charge carriers in nonpolar liquids under the influence of a high electric field strength gives rise to a number of effects which may have some technological importance. 

The electrohydrodynamic motion connected with the passage of an injection current through an insulating liquid can be employed in the construction of pumps (Bryan and Seyed-Yagoobi, 1991 Sharbaugh and Walker, 1985). Unipolar ion injection into dielectric fluids produces pressures and mechanical movement (Pickard, 1963). 

Polymerization of aromatic compounds is initiated by injected charges. Positive ions, M+, accept an electron from a neutral molecule, M, and a chemical bond is formed between the ion and the molecule, such that 

The process comes to an end when the polymer cation encounters an impurity molecule (S) with a lower ionization energy than M. An electron is transferred and the chain is terminated. 

The formation of the starter cations M+ can occur at tips or wedges where the field enhancement promotes field ionization of the adjacent molecules (Schnabel and Schmidt, 1973 Wablat et al., 1975). In partial discharges occurring in transformer oil, similar polymerization processes are leading to the formation of wax (Fuhr and Schmidt, 1988). 

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