Discharge at the Microscale: Using Optical Tweezers to Observe Muon-Induced Discharges of a Levitated Microparticle in Air

TL;DR

This study uses optical tweezers to observe and analyze spontaneous microdischarges of levitated microparticles in air, revealing ionizing radiation as a key trigger at microscopic scales.

Contribution

It demonstrates that micron-scale discharges are driven by ion capture from passing radiation, not classical gaseous breakdown, advancing understanding of discharge physics at small scales.

Findings

Microdischarges have a typical size of ~40 elementary charges.

Discharges can be as small as a few elementary charges.

Ionizing radiation triggers microdischarges via ion capture.

Abstract

Electrical discharge at the smallest possible length and charge scales is not well understood. Using optical tweezers, we investigate spontaneous discharges of a single micron-scale particle levitated in air. These ``microdischarges'' have a typical size of $\sim$40 $|e|$, but can be as small as a few $|e|$ and as large as several hundred. The absence of a well-defined trigger charge and the weak dependence on particle size suggest events are not classical gaseous breakdown. Instead, we show that microdischarge events arise from the rapid capture of ions left in the tracks of nearby passing ionizing radiation. Our results highlight the role of natural ionizing radiation in initiating micron-scale discharges and provide a platform for studying discharge physics in electrode-free environments and at the smallest scales.