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13Complex Systems of Charged Particles and their Interactions with Electromagnetic Radiation 2016
HORIZONTAL INTER-PARTICLE DISTANCE DEPENDENCE ON ION TEMPERATURE IN DUSTY PLASMA
VSNikolaev1,2, A.V. Timofeev1,2
JIHTRAS, Moscow, Russia, e-mail: timofeevalvl@gmail.com 2MIPT, Moscow, Russia, e-mail: vladiorussia@mail.ru Dusty plasma is an ionized gas containing nanometer to millimeter sized particles of condensed matter. Due to the different mobility of electrons and ions dust particles suspended in plasma acquire high fluctuating electric charge, thus interact strongly. This leads to natural appearance of liquid and crystalline states in dusty plasma system [1]. The problem of correct description of particles interaction remains unsolved because interaction potentials are multiparticle and shielding is non-linear in most cases.
Two potentials (Yukawa potential and Gurevich polarization potential) are used for dusty particles suspended in a parabolic trap in the positive column of helium DC glow discharge. The description of typical experiments with dusty plasma in DC glow discharge is given in [2,3]. It is assumed that in the horizontal direction particle equilibrium is determined by the balance of trap attraction and inter-particle repulsion. The balance equation is solved for inter-particle distance dependence on ion temperature: (1) in an assumption that inter-particle distance almost equals screening length in plasma and (2) numerically. Theoretical results are compared with experimental data. The authors thank I.S. Samoylov and V.P. Baev for provided materials and valuable comments on details of their experiment.
In case (1) the best approximation of experimental points is provided by the Yukawa potential with the effective screening length where is ion Debye length, at the
pressure 8.5 mBar in the temperature range 200-300 K. In case (2) the numerical solution gives the best result for the Yukawa potential in the same conditions. Both approaches give unsatisfactory results at low temperatures. It is supposed that taking into account molecular ions and metastable molecula impact on screening length at low temperatures is necessary.
The authors acknowledge the support of the Russian Science Foundation (project No. 1419-01295).
References
[1] Fortov, V.E., Morfill, G.E., Complex and dusty plasmas from laboratory to space, London: CRC Press, 2008, 110-140
[2] Tsytovich V.N., UFN, 1997, 167, 57-99
[3] Antipov, S.N., Asinovskii, E.I., Kirillin, A.V., Mayorov, S.A., Markovets, V.V., Petrov, O.F., Fortov V.E., JETP, 2008, 106, 830-837
