Conditioning of HV Electrodes

This week we successfully approached the point of electrode conditioning with our high voltage system. In previous attempts, we were forced to stop short of reaching a high enough voltage due to cable failure–22 kV was the highest we could get. On Tuesday, we were able to reach 27.9 kV on our 30 kV power supply when our picoammeter alerted us to high current discharges, some as high ~ 1 uA. This, in combination with an observed rise in pressure of our vacuum system, indicated to us that minute current discharges between the electrodes were likely occurring. Shown in the plot is a plot of the current between the electrodes–the leakage current– vs. the voltage generated by the power supply. We’ve shown the current in units of volts (V) due to the rapid, order-of-magnitude changes of leakage current. One can see that the current is very consistently flat during the ramping up process (blue data points). At 27.9 kV, the current spiked. As we ramped down the voltage (red points), the leakage current remained high. This “memory” the electrodes exhibit is typical of the conditioning process. -RR