Breakdown patterns in Branly's coheror

TL;DR

This study uses thermal imaging to visualize electrical conduction paths formed by the Branly effect in aluminum granular media, revealing multiple breakdowns at high voltages with rapid rise times.

Contribution

First direct thermal imaging visualization of electrical paths created by the Branly effect in a 2D metallic granular medium.

Findings

Multiple breakdowns occur at voltages above 500 V

Breakdowns happen with rise times around 100 microseconds

Thermal imaging reveals the formation of conductive paths

Abstract

We use thermal imaging of Joule heating to see for the first time electrical conducting paths created by the so-called Branly effect in a two-dimensional metallic granular medium (aluminium). Multiple breakdowns are shown to occur when the medium is submitted to high voltage increases (more than 500 V) with rise times close to one hundred of microseconds.