High electric field development for the SNS nEDM Experiment

TL;DR

This paper reports on the development of high electric fields in liquid helium for the neutron EDM experiment, demonstrating the ability to apply fields exceeding 100 kV/cm in a controlled test setup.

Contribution

It introduces a new high voltage test apparatus and provides initial results on electric breakdown in liquid helium at high fields.

Findings

Fields exceeding 100 kV/cm were achieved in liquid helium.

Electric breakdown can be studied effectively at various pressures.

The apparatus supports the development of the neutron EDM experiment.

Abstract

A new experiment to search for the permanent electric dipole moment of the neutron is being developed for installation at the Spallation Neutron Source at Oak Ridge National Laboratory. This experiment will be performed in liquid helium at ? 0:4 K and requires a large electric field (E ~ 75 kV/cm) to be applied in liquid helium. We have constructed a new HV test apparatus to study electric breakdown in liquid helium. Initial results demonstrated that it is possible to apply fields exceeding 100 kV/cm in a 1 cm gap between two electropolished stainless steel electrodes12 cm in diameter for a wide range of pressures.