Correlation between coupled voltage and discharge current

When the discharge voltage is +8kV and electrode approaching speed is 0.8m/s, the test results were sorted and investigated and several ideas are drawn as follows: there are better linear relations between the coupled voltage peak-to-peak value, discharge current peak value and current derivative maximum value. These three parameters are linear with the discharge current rise time. And the relative amplitude of several repeatable frequency points is not linear with these parameters at all.