Searcharxiv⌕ Search

arXiv subjects

Fu-cheng Liu

Publications and source records attributed to Fu-cheng Liu.

6 recordsLinked to original sources
arXiv2026

Separation of bi-dispersed microspheres in dusty plasma ratchet experiments

It is demonstrated experimentally that the effective separation of bi-dispersed microspheres (dust particles) in the underdamped and strongly-coupled regime is realized using a designed dusty plasma ratchet. Experimental findings reveal that these dust particles can undergo directional transport at varying speeds, even moving in opposite directions depending on the discharge conditions, enabling successful particle separation. Numerical simulations of the plasma environment surrounding the dust particles are performed using fluid simulations of the capacitively coupled discharge of Argon. The simulation results indicate that the bi-dispersed dust particles are suspended at different balance heights within the plasma sheath and experience distinct ratchet potentials that govern their directional transport, resulting in varied flow velocities. The discovery of height-dependent transport of dust particles here provides insights of transport fundamental of underdamped strongly-coupled particles in dusty plasma ratchets.

physics.plasm-ph↗
arXiv2023

Separating micrometer-sized particles utilizing a dusty plasma ratchet

Directional transport-dominated particle separation presents major challenges in many technological applications. The Feynman ratchet can convert the random perturbation into directional transport of particles, offering innovative separation schemes. Here, we propose the design of a dusty plasma ratchet system to accomplish the separation of micron-sized particles. The dust particles are charged and suspended at specific heights within the saw channel, depending on their sizes. Bi-dispersed dust particles can flow along the saw channel in opposite directions, resulting in a perfect purity of particle separation. We discuss the underlying mechanism of particle separation, wherein dust particles of different sizes are suspended at distinctive heights and experience electric ratchet potentials with opposite orientations, leading to their contrary flows. Our results demonstrate a feasible and highly efficient method for separating micron-sized particles.

physics.plasm-ph↗
arXiv2020

Experimental demonstration of a dusty plasma ratchet rectification and its reversal

The naturally persistent flow of hundreds of dust particles is experimentally achieved in a dusty plasma system with the asymmetric sawteeth of gears on the electrode. It is also demonstrated that the direction of the dust particle flowcan be controlled by changing the plasma conditions of the gas pressure or the plasma power. Numerical simulations of dust particles with the ion drag inside the asymmetric sawteeth verify the experimental observations of the flow rectification of dust particles. Both experiments and simulations suggest that the asymmetric potential and the collective effect are the twokeys in this dusty plasma ratchet.With the nonequilibrium ion drag, the dust flow along the asymmetric orientation of this electric potential of the ratchet can be reversed by changing the balance height of dust particles using different plasma conditions.

physics.plasm-ph↗
arXiv2014

Cycloid motions of grains in unmagnetized dust plasma

Hypocycloid and epicycloid motions of irregular grain (pine pollen) are observed for the first time in unmagnetized dust plasma in 2D horizontal plane. Hypocycloid motions occur both inside and outside the glass ring which confines the grain. Epicycloid motion only appears outside the glass ring. Cuspate cycloid motions, circle motion, and stationary grain are also observed. All these motions are related with both the initial conditions of dropped grain and the discharge parameters. The Magnus force originated from the spin of the irregular grain is confirmed by comparison experiments with regular microspheres, and it plays important role on these (cuspate) cycloid motions. The observed complex motions are explained in term of force analysis and numerical simulations. Periodical change of the cyclotron radius as the grain travelling results in the (cuspate) cycloid motions. Our results show that the (cuspate) cycloid motions are distinctive features of irregular grain immersed in plasma.

physics.plasm-ph↗
arXiv2013

Interaction of multi-armed spirals in bistable media

We study the interaction of both dense and sparse multi-armed spirals in bistable media modeled by equations of FitzHugh-Nagumo type. Dense 1-armed spiral is characterized by its fixed tip. For dense multi-armed spirals, when the initial distance between tips is less than a critical value, the arms collide, connect and disconnect continuously as the spirals rotate. The continuous reconstruction between the front and the back drives the tips to corotate along a rough circle and to meander zigzaggedly. The rotation frequency of tip, the frequency of zigzagged displacement, the frequency of spiral, the oscillation frequency of media, and the number of arms satisfy certain relations as long as the control parameters of the model are fixed. When the initial distance between tips is larger than the critical value, the behaviors of individual arms within either dense or sparse multi-armed spirals are identical to that of corresponding 1-armed spirals.

nlin.PS↗