Kerr electro-optic field mapping measurements in high voltage stressed liquid and gaseous sulfur hexafluoride

When stressed by high electric fields, liquid and gaseous SF
6
become detectably birefringent. Liquid SF
6
at ∼350 psi and room temperature has a Kerr constant on the order of 10
⁻¹⁵
m/V
²
for light at the free space wavelength of 633nm, which is comparable to values reported for transformer oil, polyethylene, and PMMA. The Kerr constant of gaseous SF
6
is measured to strongly decrease with density. Electric field measurements between coaxial cylindrical electrodes are described where the inner cylinder is entirely supported by a half round cylinder of PMMA. The aim of these measurements is to describe surface charge accumulation at a solid/gas interface and its effect on surface discharges.