Formation of structures from dusty clusters in cryogenic plasma of glow discharge

Summary form only given. The structures formed by single dust particles or structures consisting of vertical chains of dust particles appear in most cases at room temperatures in dusty plasma of glow discharge in neon [1]. In this work, it was discovered the formation of structures consisting from structures of clusters in dusty plasma at a temperature of liquid nitrogen. Dusty plasma was produced in the glow discharge in neon, where the 4.14 micron size melamine formaldehyde particles were injected. The discharge tube was cooled in cryostat. The optical images of dust structures, the current-voltage characteristics (CVC) of positive column of glow discharge and the temperature of discharge tube walls were registered. Depending on the pressure of neon the different structural transitions in the regions of growing CVC at low discharge currents 0.01≤ I ≤ 1 mA were observed. One may determine the three specific regions of structural transitions. The region 1 is limited by current I ≤ 1 mA at reduced pressure Pr ≥ 0.1 torr cm and by current I ≤ 0.65 mA at Pr ≤ 0.5 torr cm. The region 2 is limited by current I ≤ 0.65 mA at Pr ≥ 0.5 torr cm and I ≤ 0.4 mA at Pr ≤ 0.7 torr cm. The region 3 is located above the region 2 at Pr ≥ 0.7 torr cm, at discharge current 0.01 ≤ I ≤ 3.5 mA approximately. In the region 1 there appear the ordered structures with the lattice similar to the hexagonal with 1D, 2D or 3D clusters located in the sites of lattice. The dust particles forming 2D or 3D cluster, in turn, are in ordered state. The transition from 1D to 2D and from 2D to 3D clusters is observed at the increase of gas pressure. In the region 2 the destruction of crystals consisting of 3D clusters and the destruction of ordered 3D clusters into individual threadlike (1D) clusters is observed. In the region 3 the dense disordered structures consisting from threadlike clusters were o- served. The distance between the threadlike clusters was less than 40 microns, while the distance between the dust particles in threadlike clusters was about 10 microns. To the right from the border of regions 1 and 2 (with the increase of current) the melting of all types of observed ordered structures appeared. It was found that the regions of existence of structured clusters and the regions of structural transitions, were characterized by the higher values of the reduced longitudinal electric field strength than the regions of destruction of ordered structures.