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23Complex Systems of Charged Particles and their Interactions with Electromagnetic Radiation 2019
FAST ROTATION OF THE DUST STRUCTURE UNDER ACTION OF A STRONG MAGNETIC FIELD IN THE REGION OF THE NARROWING OF THE DC GLOW DISCHARGE CURRENT CHANNEL
L.G. Dyachkov1, E.S. Dzlieva2, M.A. Ermolenko2, L.A. Novikov2,
S.I. Pavlov2, V.Yu. Karasev2
Joint Institute for High Temperatures of the Russian Academy of Sciences, Moscow, Russia,
e-mail: dyachk@mail.ru 2Saint-Petersburg State University, Saint-Petersburg, Russia, e-mail: plasmadust@yandex.ru
It is well known that a trap for dust particles occurs in strata of a dc glow discharge [1]. When a longitudinal magnetic field is applied, the dust particle structure begins to rotate. In the stratum trap, with increasing magnetic field B the direction of rotation changes: at low fields (B < 102 G) the magnetic induction B and angular velocity Q vectors are oppositely directed, while at strong fields (B > 103 G) they are unidirectional. However, the occurrence of a trap for the dust structure is also possible in the region of the narrowing of the current channel by the diaphragm used to stabilize the discharge near the cathode [1]. Here the dust structure also rotate in magnetic field, however we have not observed the rotation inversion. At any magnetic fields up to 104 G, the field B and angular velocity Q are oppositely directed. The angular velocity of rotation of the dust structure in this trap in neon is several times higher than that in the stratum and reaches 15 rad/s.
Based on the theoretical approach developed by us earlier [2] we have estimated the rotation velocity of the dust structure in this area. Uniform rotation of dust particles occurs under the action of the ion drag force which is balanced by the force of neutral atom gas friction. The ion azimuthal velocity is defined by two mechanisms [3]: (i) the ion drift in the crossing radial ambipolar electric Er and axial magnetic B fields and (ii) radial gradient of the ion pressure (diamagnetic ion current). Using some assumptions about the ion distribution over the discharge cross section near the diaphragm, we have obtained a qualitative and partly quantitative agreement of the calculation with experimental data for the dust structure rotational velocity. A possible reason for some discrepancy between the calculation and experiment in strong magnetic fields B ~ 104 G is discussed.
References
[1] Complex and Dusty Plasmas: from Laboratory to Taylor & Francis Group, New York 2010.
[2] M.M. Vasiliev et al. 2011 EPL 93 15001.
[3] V.E. Golant, A.P. Zhilinskii and S.A. Sakharov. York 1980.
Space. Edited by V.E. Fortov and G.E. Morfill. Fundamentals of Plasma Physics. Wiley, New
