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12Complex Systems of Charged Particles and their Interactions with Electromagnetic Radiation 2018
STRUCTURES OF CHARGED MACROPARTICLES IN GAS DISCHARGE PLASMA AND IN INHOMOGENEOUS MAGNETIC FIELDS
M.M. Vasiliev12, O.F. Petrov12
1 Joint Institute for High Temperatures RAS, Moscow 125412, Russia 2Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russia
The results of experimental study of the formation of Coulomb structures in a DC glow discharge plasma and in inhomogeneous magnetic fields at cryogenic temperatures are presented.
At present the thermodynamically closed systems are studied well enough, including such processes as phase transitions or transport. Meanwhile, the vast majority of objects in nature are open systems. One of the most interesting and practically important properties of open dissipative systems is their ability for self-organization. Classic examples are the formation of Benard cells in a heated fluid, transition of the fluid / gas flow from laminar to turbulent regime, the initiation of coherent laser radiation, etc. In our work we have investigated the formation and evolution of open dissipative Coulomb systems of charged particles.
To study a gas discharge dusty plasma at cryogenic temperatures, we cooled down the walls of a discharge tube with liquid helium and its vapor. Lowering the temperature of the plasma-supporting gas to the temperature of liquid helium can change a coupling parameter of the dusty plasma by two orders of magnitude. During the experiment, as the temperature within the cryostat increased from 4.2 to 6 K, we observed a decrease of the kinetic energy of the macroparticles forming the dust structure. It resulted, in turn, in localization of part of the particles in the dust cloud and formation of dust chains. With temperature rise, there was an increase in both the lifetime of the chains, and their amount and length.
For the formation of an ensemble of charged particles, we proposed a particle retention technique based on the Meissner effect of displacing the magnetic field from the region of the superconducting phase and the levitation of superconductors. We observed experimentally structures, consisted up to ~ 103 highly charged particles of 30-60 microns in diameter made of high-temperature superconducting ceramics YBa2Cu3O7 in a static magnetic trap in liquid nitrogen and its vapor at a temperature of 77 K. We obtained data concerned with the dynamics of active charged macroparticles in an inhomogeneous magnetic field under laser action. Also we estimated the values of coupling parameter r (~103) and the Lindemann parameter (~ 0.03), which are characteristic of strongly correlated crystalline or glass-like structures.
