---
title: "Corona discharge"
description: "A corona discharge is a self-sustaining electrical discharge that occurs when the field gradient around a sharp electrode exceeds the breakdown threshold of the surrounding gas. In an ESP the corona forms around the discharge electrode, ionises flue-gas molecules, and the resulting ions attach to dust particles. The charged particles then drift to the collecting electrodes under the electric field."
canonical_url: "https://sylio.co/glossary/corona-discharge"
last_updated: "2026-06-28T02:29:30.503Z"
---

A **corona discharge** is a self-sustaining electrical discharge that occurs when the field gradient around a sharp electrode exceeds the breakdown threshold of the surrounding gas. In an [ESP](/glossary/electrostatic-precipitator) the corona forms around the [discharge electrode](/glossary/discharge-electrode), ionises flue-gas molecules, and the resulting ions attach to dust particles. The charged particles then drift to the [collecting electrodes](/glossary/collecting-electrode) under the electric field.

## Negative corona dominates

Industrial ESPs almost always run on negative corona because it sustains a higher voltage before sparking — but it also produces some ozone, which is one of the reasons WESPs in confined ventilation paths sometimes use positive corona instead.

## What disrupts the corona

- **Excessive dust on the collecting plate** — raises plate-face voltage, narrows the working gap
- **High ash resistivity** — traps charge in the dust layer, leading to [back-corona](/glossary/back-corona)
- **Bent or broken discharge electrodes** — local field collapse, sparking, eventual short
- **Fouled discharge electrode tips** — suppressed corona, reduced ion current

Acoustic cleaning addresses two of these (plate dust thickness and discharge-electrode fouling) without the broken-electrode risk of aggressive mechanical rapping.

## Related terms

- [Electrostatic precipitator](/glossary/electrostatic-precipitator)
- [Discharge electrode](/glossary/discharge-electrode)
- [Back-corona](/glossary/back-corona)
- [Resistivity (fly-ash)](/glossary/resistivity)