Dielectric Strength of Noble and Quenched Gases for High Pressure Time Projection Chambers

TL;DR

This study experimentally measures the dielectric breakdown strengths of various noble and quenched gases at high pressures and develops a predictive microphysical model that outperforms traditional theories.

Contribution

It provides new experimental data and a highly predictive microphysical model for dielectric breakdown in gases used in high pressure time projection chambers.

Findings

Noble gases have predictable breakdown behavior at high pressure.

The microphysical model outperforms traditional Paschen and Meek models.

Different gases require different models for accurate breakdown prediction.

Abstract

Dielectric breakdown strength is one of the critical performance metrics for gases and mixtures used in large, high pressure gas time projection chambers. In this paper we experimentally study dielectric breakdown strengths of several important time projection chamber working gases and gas-phase insulators over the pressure range 100 mbar to 10 bar, and gap sizes ranging from 0.1to 10 mm. Gases characterized include argon, xenon, CO2, CF4, and mixtures 90-10 argon-CH4,90-10 argon-CO2and 99-1 argon-CF4. We develop a theoretical model for high voltage breakdown based on microphysical simulations that use PyBoltz electron swarm Monte Carlo results as input to Townsend- and Meek-like discharge criteria. This model is shown to be highly predictive at high pressure, out-performing traditional Paschen-Townsend and Meek-Raether models significantly. At lower pressure-times-distance, the Townsend-like model is an excellent description for noble gases whereas the Meek-like model provides a highly accurate prediction for insulating gases.