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0INVESTIGATION OF MULTICOMPONENT DUSTY PLASMA IN THE DC GLOW DISCHARGE AT TEMPERATURES BELOW 2 K
Boltnev R.E., Kononov E.A., Vasiliev M.M., Trukhachev F.M., Petrov O.F.
Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow, Russia,
boltnev@gmail.com
Multimodal dusty plasma in a positive column of the direct current (DC) glow discharge at temperatures 1.4 ^ 2.1 K has been studied experimentally and theoretically for the first time. As the plasma components there were found charged polymer nanoclusters and helical filaments in addition to electrons, atomic and molecular helium ions, as well as charged dusty particles of CeO2 in the DC glow discharge cooled by superfluid helium [13]. The discharge current was varied within the range from 1 to 100 at the helium gas pressure 3 ^ 6 Pa.
A liquid-like dusty plasma structures appeared after injection of polydisperse CeO2 particles in the glow discharge. The coupling parameter values ~10 evaluated for the dusty plasma structures observed correspond very well to their liquid-like type.
Different self-organization phenomena were observed in such plasma: the formation of a nanoparticle cloud and nonlinear dust-acoustic instability within it, the synthesis of quasi one-dimensional structures (helical filaments). Analysis of the experimental conditions and the filament composition allows us to conclude that the filaments and nanoclusters were formed due to intense sputtering of the clay insert with a total flux ~100 ng/s of sputtered materials at the power released within the discharge tube less than 0.1 W. The synthesis rates for nanoclusters and filaments, correspondingly, ~10 ng/s and ~1 ng/s were estimated. Nanoclusters with the diameters from 20 to 80 nm carried the charges ~e. Solid helical filaments with length up to 5 mm, diameter up to 22 p,m, total charges ~106e, levitated in the gas discharge were found after experiments on the discharge tube wall [2]. Fast growth of quasi one-dimensional structures, the filaments with high aspect ratio ~100, in plasma at T < 2 K was explained by self-assembly of polarizable materials in strongly in-homogeneous electric fields on the tips of cellulose fiber protruding from the clay insert surface [3].
The main discharge parameters were estimated on the basis of the dust-acoustic wave analysis [4]. In particular, the temperature and density of helium ions, 45 K and ~108 cm-3, respectively, as well as the electron and ion Debye lengths as high as «2 mm and «30 p,m were found.
References
1. Boltnev R.E., Vasiliev M.M., Kononov E.A., and Petrov O.F. // J. Exp. Theor. Phys. - 2018. -V. 126. - P. 561-565.
2. Boltnev R.E., Vasiliev M.M., Kononov E.A., and Petrov O.F. // Sci. Rep. - 2019. - V. 9. - P. 3261.
3. Boltnev R.E., Kononov E.A., Trukhachev F.M., Vasiliev M.M., and Petrov O.F. // Plasma Sources Sci. Technol. - 2020. - V. 29. - P. 085004.
4. Trukhachev F.M., Boltnev R.E., Vasiliev M.M., and Petrov O.F. // Molecules. - 2022. - V. 27. - P. 227.
