dimple crystal

dimple crystal

[′dim·pəl ‚krist·əl]
(cryogenics)
A periodic pattern of hexagons that forms on a liquid helium surface when electrons, forming an electric charge sheet, are trapped at the surface, and an intense electric field is applied; the hexagons are typically about 2 millimeters across and the interiors of the hexagons are depressions about 10 micrometers deep.