Classification of vacuum arc breakdowns in a pulsed DC system

TL;DR

This paper analyzes the microscopic phenomena of vacuum arc breakdowns in pulsed DC systems, classifying events into primary and secondary types based on statistical properties, to improve high-voltage system reliability.

Contribution

It introduces a classification scheme for vacuum arc breakdowns based on statistical analysis of experimental data from high-gradient pulsed DC systems.

Findings

Primary breakdowns follow a power law distribution with slope ~1.33.

Secondary breakdowns depend heavily on pulsing parameters.

Breakdown characteristics are consistent across different experimental setups.

Abstract

Understanding the microscopic phenomena behind vacuum arc ignition and generation is crucial for being able to control the breakdown rate, thus improving the effectiveness of many high-voltage applications where frequent breakdowns limit the operation. In this work, statistical properties of various aspects of breakdown, such as the number of pulses between breakdowns, breakdown locations and crater sizes are studied independently with almost identical Pulsed DC Systems at the University of Helsinki and in CERN. In high-gradient experiments, copper electrodes with parallel plate capacitor geometry, undergo thousands of breakdowns. The results support the classification of the events into primary and secondary breakdowns, based on the distance and number of pulses between two breakdowns. Primary events follow a power law on the log--log scale with the slope $\alpha \approx 1.33$, while the secondaries are highly dependent on the pulsing parameters.