Measurement of space charge in negative corona on a small corona cage

A corona cage fitted with charge density measurement equipment is set up in the laboratory. Propagating in the space charge area, sound wave will modulate space charge to generate variable electric field. A mathematical model is established to determine the relation between charge density and electric field. Finally, the distribution of charge density is obtained. Taking wire radius as inset space and applied voltage as -40 kV, measured distribution has well-known declining-shape curve, with a minimum at the cylinder wall of 2×10
^-5
C/m
³
and maximum value at the wire reaching 1.6×10
^-4
C/m
³
. At the same time, numerical simulation is set up for comparison. Cosine similarity, Pearson correlation coefficient and maximum charge density ratio are applied to compare calculation results and measurement results. Measurement results agree well with calculation results to check the validity of proposed method.