Lichtenberg figure

Electrical discharges can leave tree-like, fern-like or branching channels on the surface of an insulator or within its volume. Such patterns arise when an intense electric field makes a normally insulating material locally conductive, allowing charge to move along paths that branch through or over the material. The fine geometry depends on the material, its electrical state and the conditions of discharge; the pattern is not a fixed template. In the specific modern research setting of irradiated polymers, high-speed imaging has revealed different forms of electrical-tree growth, including a reported ivy-like type.

In 1777, German physicist Georg Christoph Lichtenberg described a way to record electrical patterns. He charged insulating surfaces such as resin, glass or hard rubber using an electrostatic generator, dusted them with powders and transferred the resulting designs to paper. He observed that patterns differed with the sign of the charge. His experiments helped establish a durable connection between electricity and branching forms, although the physical processes behind modern three-dimensional discharge structures are more complex than the original surface demonstrations.

Lichtenberg figures provide visible evidence of electrical breakdown, a failure process in which an insulating material becomes conductive under a sufficiently strong electrical stress. In devices and spacecraft, unwanted discharges inside or across dielectric components can damage electrical systems. Studying the growth and speed of discharge channels helps researchers understand breakdown and informs efforts to design more robust insulating materials. Specialized recording instruments have also used discharge traces to document high-voltage surges.

The name is used for several related but not identical patterns. It can refer to historical powder patterns on charged surfaces, branching discharges produced in solid dielectrics, or tree-like electrical channels imaged during controlled experiments. Branching marks sometimes reported on skin after lightning strikes are colloquially called lightning flowers and are also referred to as Lichtenberg figures, but they are a separate biological effect, not an electrical tree embedded in an insulator.