Liquid Argon Dielectric Breakdown Studies with the MicroBooNE Purification System

Understand

The proliferation of liquid argon time projection chamber detectors makes the characterization of the dielectric properties of liquid argon a critical task.

• To improve understanding of these properties, a systematic study of the breakdown electric field in liquid argon was conducted using a dedicated cryostat connected to the MicroBooNE cryogenic system at Fermilab.
• An electrode sphere-plate geometry was implemented using spheres with diameters of 1.3 mm, 5.0 mm, and 76 mm.
• The MicroBooNE cryogenic system allowed measurements to be taken at a variety of electronegative contamination levels ranging from a few parts-per-million to tens of parts-per- trillion.