A New Representation of Paschen's Law Suitable for Variable Temperature Power Applications

A new method to represent Paschen's law to estimate the dielectric strength of gaseous media over a wide range of temperatures is presented. In the new representation the breakdown strength is a function of the product of gas mass density and gap distance between the electrodes (p.d) rather than the product of gas pressure and gap distance (p.d) used in the standard form. The necessity of the new representation is articulated based on the fact that the dielectric strength of a gaseous medium scales with density, and the density depends not on the pressure alone, but also on the temperature. Representing Paschen's law using mass density accounts for the dependence of dielectric strength on the temperature and pressure of the gas, and facilitates its application for estimations of dielectric strength of gas media at any temperature and pressure. The application and the necessity of the new representation is demonstrated using the test case of gas cooled high temperature superconducting power devices that operate at variable temperature and pressure.