High Voltage Component Testing for the nEDM Experiment at SNS

The neutron electric dipole moment (nEDM) is a measurement of charge separation within the neutron. Insight into the nEDM could give light to some of physics’ unanswered questions, like why there appears to be more matter than antimatter in the universe. The nEDM experiment at Oak Ridge National Laboratory’s Spallation Neutron Source (SNS) is designed to search for the nEDM at the level of 3 x 10^-28 e-cm, nearly one hundred times lower than the present limit. The experiment calls for an electric field of 75 kV/cm in a large volume of liquid helium at 0.4K. To develop this capability, the Half Scale High Voltage system (HSHV) and the Small Scale High Voltage system (SSHV) are currently being tested at Los Alamos National Laboratory. The HSHV uses a custom high voltage (HV) chain to deliver up to 200kV to a 40 liter liquid helium central volume. To qualify the performance of HV chain, multiple tests were conducted in a Room Temperature High Voltage system (RTHV) under vacuum. After testing in the RTHV, the HV system was moved to the HSHV for cryogenic testing. Additionally, the SSHV is being prepared for liquid helium testing that will complement that of the HSHV.  Details on the voltage chain assembly, recent work on the SSHV, and tests inside the RTHV and HSHV will be presented.