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20Complex Systems of Charged Particles and their Interactions with Electromagnetic Radiation 2019
WAKEFIELD AROUND A DUST PARTICLE IN STREAMING PLASMAS AND DYNAMICS OF THE DUSTY PLASMAS IN EXTERNAL MAGNETIC
FIELD
T.S. Ramazanov, K. N. Dzhumagulova, Zh. A. Moldabekov,A.R.Abdirakhmanov,
R.U. Masheeva, M.K. Dosbolayev, S.K. Kodanova
Al Farabi Kazakh National University, Institute of Experimental and Theoretical Physics, Almaty,
Republic of Kazakhstan
Complex plasmas in an external magnetic and electric fields are investigated by means of computer simulation and experimentally. We present results for streaming plasmas and for magnetized non-ideal plasmas.
Streaming complex plasmas areroutinely generated in high energy density facilities (e.g., the tokamak edge), industrial setups, and in experiments on fundamental dusty plasma research [1, 2]. We present our results on the induced charge density distribution of the plasma constituents around dust particle. The subsonic, sonic, and supersonic regimes are considered taking into account the non-Maxwellian distribution of the flowing ions. In contrast to the wake potential, the density decays strongly monotonically in the plasma wake and does not exhibit an oscillatory pattern or trailing maxima. Therefore, the picture of an ion focusing effect creating a separated ion region downstream was not confirmed. We have computed the dipole moment of the deformed screening cloud as the function of the Mach number, where Mach number is defined as the ratio of the ion streaming velocity and the ion sound speed.This quantity is of central importance for the simplified analytical models describing dust particles interaction in streaming plasmas (in an external electrical field) [3].
Furthermore, the effects resulted from competition between an external magnetic field and gas induced friction in non-ideal magnetized two-dimensional dusty plasma wererevealed by the Langevin dynamics computer simulation. We found that the presence of the friction leads to the disappearance of a collective oscillation mode—related to the cyclotron frequency of the dust particles—anddecreasing in the dominant mode. Moreover, new interesting observation is made: at lower friction rates, an increase in the magnetic field strength leads to an increase in the main peak in the Fourier transformation of the velocity autocorrelation function, while at higher friction rates the opposite is true [4].
To study the dust particles dynamics in partially magnetized complex plasmas, the experiments on dust particles rotation in the DC glow discharge in an external magnetic field were performed. In these experiments, the dust particles rotation direction is shown to depend on the angle between the magnetic field induction and electric field. Particularly, for the first time, the rotation due to the radial component of the magnetic field was observed.A simple analytical model describing the experimental observations is presented [5].
References
[1] R. A. Quinn, J. Goree. // Phys. Rev. Lett. - 2002. - Vol. 88. - P. 195001.
[2] S. K. Kodanova et al. // IEEE Transactions on Plasma Science. - 2016. - Vol. 44. - P. 525.
[3] T. S. Ramazanov et al. // Phys. Rev. E. - 2016 - Vol. 93 - P. 053204.
[4] K. N. Dzhumagulova et al. // Phys. Rev. E - 2014. - Vol. 89 - P. 033104;
[5] P. Hartmann, J. C. et al., // Phys. Rev. E - 2019. - Vol. 99 - P. 013203
[6] A.R. Abdirakhmanov, Zh.A. Moldabekov, S.K. Kodanova, M.K. Dosbolayev, T.S. Ramazanov, Rotation of dust structures in a magnetic field in a DC glow discharge, submitted for publication (2019).
