Dielectric loss behavior of liquid nitrogen in uniform fields: Millimeter gap

Liquid nitrogen is a simple molecular liquid having no internal dipole moment. Thus it is not expected to show any dielectric loss below microwave frequencies. However, measurements carried out on liquid nitrogen at uniform fields in millimeter gap show that it exhibits measurable loss even at power frequency. Interestingly, this loss shows a tendency to decrease with increasing electric stress over a certain range, the so-called Garton effect. Data on dielectric loss of liquid nitrogen in uniform electric field and millimeter gap, both as a function of stress as well as pressure, are presented and the origin of this loss discussed.