This afternoon TM4 with the coil removed was tested with HV. The EINZEL LENS was first tested independently while the bias canbus was being repaired. The current on the EL looked stable at 25kV for 5 minutes. At 27.5kV the current becomes unstable and occasionally sparks. This voltage was held for 30 minutes but the current did not appear to be becoming more stable. Further extended testing would be required to determine if this can be conditioned out. At this point I would suggest the EL has a HV limit near 25kV.

The BIAS and EL were then brought up to 35kV and 17.5kV respectively. This voltage was held for 35 minutes with the BAIS only sparking twice. The module can most likely hold a higher voltage but for the next 2 runs does not require more than 35kV. Further testing was not completed due to time constraints. It is recommended during the shut down that TM4 is tested to its limits. The data from the testing has been attached.