Electrical Breakdown Engineering for the Cryogenic High-Voltage Multiplier for SNS nEDM*

The nEDM@SNS experiment will employ a system of voltage amplification electrodes called a Cavallo Multiplier to produce the high voltage necessary for the neutron electric dipole moment's sensitivity goal of 10^-28 e cm. These electrodes must be fabricated out of copper-coated PMMA (resin) to reduce eddy current heating and magnetic field disturbances in the sub-kelvin measurement region. Electrical breakdown is a big concern for these delicate electrode surfaces. Strategies to prevent spark damage include loading the apparatus under pressurized liquid helium and designing a sacrifical disposable button. These strategies will be discussed in the context of the electric breakdown engineering for the nEDM@SNS experiment.