Small systems of laser-driven active Brownian particles: Evolution and dynamic entropy

Abstract

We investigate the evolution of small systems of strongly interacting active Brownian particles. Metal-coated grains of micron size levitating in gas-discharge plasma are irradiated by laser inducing their active motion. We present the experimentally obtained functions of mean first-passage time dynamic entropy (MFPT) for each grain in a two-dimensional system for various values of their kinetic temperature, and also the values of the fractal dimension of trajectories of these systems and their localization area and match them to the point of transformation of the system.

Active Brownian particle in homogeneous media of different viscosities: numerical simulations

“…The difference between eqn (18) and the simulation results shown in Fig. 4 does not exceed 1.5% which is comparable with the statistical measurement error in the numerical experiment.…”

“…The driving force of Janus particles in these experiments is the photophoretic force. 14,[16][17][18] In most theoretical research, the active Brownian particles are considered to be moving in an overdamped medium. 1 However, there is a lack of theory describing underdamped Brownian motion of self-propelled particles.…”

Dynamics of Active Brownian Particles in Plasma

“…We observed single particle movements under exposure of the argon laser with different values of radiation power. The particles were injected into a discharge chamber, where they started to levitate in the ring trap near the lower electrode (see [ 13 ]). The video recorded in the experiment was processed by a special program which determined the positions of the dust particle on video frames with sub-pixel accuracy.…”

“…The chamber was pumped out, after which it was filled with argon to a pressure of 3.5 Pa. From the RF generator through an impedance-matching device, a voltage of 300 V with a frequency of 13.56 MHz was applied to flat, horizontally oriented electrodes, resulting in a discharge being ignited. To form an electrostatic trap, a copper ring 35 mm in diameter was placed on the lower electrode [ 13 ]. The diameter of the ring was selected so that dust particles were reliably held by the trap, but at the same time could perform a Brownian motion of large amplitude.…”

Dynamic Effects of Laser Action on Quasi-Two-Dimensional Dusty Plasma Systems of Charged Particles

“…Using this technique, laminar flows in a dusty plasma liquid can be generated [1]; the viscosity properties, such as the coefficients of shear viscosity and shear stress, can be determined [2,3]. In previous work [4,5], the Brownian motion of dust grains in plasma was investigated by video recording of the particle dynamics, so that the friction coefficient of dust particles in the buffer gas was measured. One can also use lasers to heat dust particles and Molecules 2020, 25, 3375 2 of 8 increase their kinetic energy due to the photophoretic force; thus, phase transitions in colloidal plasma systems can be observed [6,7].…”