Ice Needle Nucleation and Dendrite Growth Under an Electric Field

Applying 0.3-1.25 kV/cm electric potential gradients to cooled water vapor triggers the copious formation of electrified ice needles, as long as 36 mm. This is completely different from the meager ice formation in the same setup but in the absence of the external field. Needle excess electric charge is evidenced by its attraction toward the electrodes and by its shape change, when the field is withdrawn. These observations are explained considering the effect of the electric potential on ice surface tension, thus decreasing or eliminating the energy barrier to ice nucleation; and the elongated ice habit that allows the accumulation of charge sufficient to create fields higher than those initially applied. Applying this information to other crystallization phenomena in various systems can contribute to improve industrial processes while preventing the consequences of undesired electrification, in industrial plants and products.