Evolution of charged grains in harmonic force field

Abstract

Evolution of the spatial structure of the massive charged grains in the presence of weak linearly space-dependent external force in a dusty plasma is studied using molecular dynamics simulation. The interaction among the dust grains in the background electron-ion plasma is described by a modified Yukawa interaction potential that includes both repulsive and attractive ranges. Evolution of the initially homogeneously distributed dust grains is followed until a quasi-stationary state is reached. Even though the external force is radially highly asymmetric, the final configuration of the charged grains can be a circular crystal. Still driven by the external force, the grains in the crystal execute synchronized oscillations in the direction of the force. The time needed to reach the quasi-stationary state decreases with increase of the strength of the external force.

Long-time evolution of charged grains in plasma under harmonic external force and after being withdrawn

“…The oscillation period of the grains in the disk cluster increases as β decreases as expected. [31] As shown in Fig. 2, after the external force vanishes at t = 2.4 × 10 4 , the grain disk first moves diagonally across the simulation box along the direction of the withdrawn external force at nearly constant speed.…”

“…The differences among the models lie in the ranges and magnitudes of the two regimes. In our simulation, the grain-grain interaction is governed by a modified-Yukawa potential [19,20,[28][29][30][31]33] U int (r i j ) = q 2 r i j exp − r i j…”

“…[3,4,[11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] Recently it has been shown that by tailoring the external force one can obtain controllable compact structures such as dust-grain crystals, [26,27] and the time required to reach the cluster state decreases with external force increasing. [28][29][30][31][32][33] Although what happens after the external force has been withdrawn can be important in many applications, [1] it has not been investigated. In this paper, we use molecular dynamics (MD) simulation to investigate the evolution of charged grains in a 2D dusty plasma under an external force, particularly the long-time evolution of the resulting grain crystal after it has been withdrawn.…”

Effect of external fields on pattern formation of charged grains in plasma

“…[1][2][3][4][5][6][7][8][9][10] We shall use the modified Yukawa potential that includes the effects of the background plasma electrons and ions on the grains. [8][9][10][33][34][35]…”