Abstract:
In this paper, electric field and space charge accumulation have been investigated for
needle-plane system (defect) under DC voltage conditions. Prolate spheroidal electrode
system, believed to be closer to needle-plane system, has been used for solving the
governing differential equations, numerically, for space charge and electric field
distributions. Unlike past works in which space charge at needle tip was assumed either
qualitatively or quantitatively, in this work, space charge formation is estimated using
nonlinearity of material properties alone. A comparison with previous methods based
on concentric spherical electrode approximations reveals that the results are different
for prolate spheroidal system at different nonlinearities. Interesting results on the role
of nonlinear conductivity on the DC electric field and space charge accumulation at
needle-tip are presented. Furthermore, needle tip-plane breakdown experiments are
conducted and the results suggest a reasonable and realistic estimate of tip-field at
breakdown, using the proposed model.
