The pulsed electric field (PEF) treatment of liquid and pumpable products contaminated with microorganisms has attracted significant interest from the pulsed power and bioscience research communities particularly because the inactivation mechanism is non-thermal, thereby allowing retention of the original nutritional and flavour characteristics of the product. Although the biological effects of PEF have been studied for several decades, the physical mechanisms of the interaction of the fields with microorganisms is still not fully understood. The present work is a study of the dynamics of the electrical field both in a PEF treatment chamber with dielectric barriers and in the plasma (cell) membrane of a microbial cell. It is shown that the transient process can be divided into three physical phases, and models for these phases are proposed and briefly discussed. The complete dynamics of the time development of the electric field in a spherical dielectric shell representing the cellular membrane is then obtained using an analytical solution of the Ohmic conduction problem. It was found that the field in the membrane reaches a maximum value that could be two orders of magnitude higher than the original Laplacian electrical field in the chamber, and this value was attained in a time comparable to the field relaxation time in the chamber. Thus, the optimal duration of the field during PEF treatment should be equal to such a time.

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The growth of water trees in polyethylene has been measured by detecting the penetration of ions from solution using instrumental neutron activation analysis. The method can accurately quantify water tree growth, something hitherto lacking in the study of polymer insulated power cables.

Low-pressure experimental data concerning fundamental gas discharge parameters may be used in compressed gases provided the gas compressibility factor is taken into consideration and that this has a significant effect on the interpretation of breakdown in sulphur hexafluoride at pressures greater than about 100 kPa (1 bar). A modified relationship giving values of the effective ionization coefficient for SF6 at high pressures is presented.