scholarly journals Possible Mechanisms of String Formation in Complex Plasmas at Elevated Pressures

Molecules ◽  
2021 ◽  
Vol 26 (2) ◽  
pp. 308
Author(s):  
Victoria Yaroshenko ◽  
Mikhail Pustylnik
Keyword(s):  
Interaction Energy ◽  
Electric Fields ◽  
Particle Interaction ◽  
Space Station ◽  
Trapped Ion ◽  
Elevated Pressures ◽  
Ion Cloud ◽  
String Formation ◽  
Complex Plasmas ◽  
Gas Pressures

Possible mechanisms of particle attraction providing formation of the field aligned microparticle strings in complex plasmas at elevated gas pressures are theoretically investigated in the light of the Plasmakristall-4 (PK-4) experiment on board the International Space Station. The particle interaction energy is addressed by two different approaches: (i) using the dynamically screened wake potential for small Mach numbers derived by Kompaneets et al., in 2016, and (ii) introducing effect of polarization of the trapped ion cloud by discharge electric fields. Is is found that both approaches yield the particle interaction energy which is independent of the operational discharge mode. In the parameter space of the performed experiments, the first approach can provide onset of the particle attraction and string formation only at gas pressures higher than 40–45 Pa, whilst the mechanism based on the trapped ion effect yields attraction in the experimentally important pressure range 20–40 Pa and may reconcile theory and observations.

scholarly journals Lane Formation in Driven Binary Complex Plasmas on the International Space Station

2010 ◽  
Vol 38 (4) ◽  
pp. 861-868 ◽  
Author(s):  
K Robert Sutterlin ◽  
Hubertus M Thomas ◽  
Alexei V Ivlev ◽  
Gregor E Morfill ◽  
Vladimir E Fortov ◽  
...  
Keyword(s):  
International Space Station ◽  
Space Station ◽  
Binary Complex ◽  
International Space ◽  
Lane Formation ◽  
Complex Plasmas

Modeling of Microstructures Actuation by the Knudsen Thermal Force

2011 ◽  
Author(s):  
Sruti Chigullapalli ◽  
Alina Alexeenko
Keyword(s):  
Impact Velocity ◽  
Electric Fields ◽  
Mean Free Path ◽  
Solid Surfaces ◽  
Finite Volume Discretization ◽  
Dimensional Phase Space ◽  
Bulk Motion ◽  
Gas Molecules ◽  
High Electric Fields ◽  
Gas Pressures

Heated microscale objects immersed in a gas ambient are subject to thermal Knudsen forces generated by the non-equilibrium energy exchange between gas molecules and solid surfaces. Knudsen forces are significant when the length scale of a temperature gradient is comparable to the gas molecular mean free path. This can occur for very low gas pressures or at extremely small length scales. The overall goal of this work is to study the feasibility of using Knudsen force as an alternative actuation mechanism for N/MEMS. The kinetic solution of Boltzmann equation using the discrete ordinate/finite volume discretization in the high-dimensional phase space is circumventing difficulties associated with traditional stochastic DSMC approach in dealing with the slow bulk motion. The comparison to measurements by (Passian et al, PRL, 2003) shows that Knudsen force is well reproduced by simulations assuming full momentum accommodation for nitrogen and argon gas and an incomplete accommodation for helium. It provides a pathway for design and analysis of devices taking advantage of the benign mechanism of the Knudsen forces, in particular, the absence of high electric fields. The analysis shows that the Knudsen force results in an impact velocity of only 0.9 cm/s whereas electrostatic forces with low voltages below 0.5V result in impact velocity in the range of 6–20 cm/s. We further discuss how Knudsen force can be used for low impact velocity actuation and also to overcome the stiction problem.

scholarly journals Direct Numerical Simulation of Particles in Spatially Varying Electric Fields †

Fluids ◽  
2018 ◽  
Vol 3 (3) ◽  
pp. 52 ◽  
Author(s):  
Edison Amah ◽  
Muhammad Janjua ◽  
Pushpendra Singh
Keyword(s):  
Particle Size ◽  
Electric Fields ◽  
Numerical Scheme ◽  
Particle System ◽  
Particle Interaction ◽  
Body Motion ◽  
Numerical Code ◽  
Electric Force ◽  
Combined System ◽  
Splitting Technique

A numerical scheme is developed to simulate the motion of dielectric particles in the uniform and nonuniform electric fields of microfluidic devices. The motion of particles is simulated using a distributed Lagrange multiplier method (DLM) and the electric force acting on the particles is calculated by integrating the Maxwell stress tensor (MST) over the particle surfaces. One of the key features of the DLM method used is that the fluid-particle system is treated implicitly by using a combined weak formulation, where the forces and moments between the particles and fluid cancel, as they are internal to the combined system. The MST is obtained from the electric potential, which, in turn, is obtained by solving the electrostatic problem. In our numerical scheme, the domain is discretized using a finite element scheme and the Marchuk-Yanenko operator-splitting technique is used to decouple the difficulties associated with the incompressibility constraint, the nonlinear convection term, the rigid-body motion constraint and the electric force term. The numerical code is used to study the motion of particles in a dielectrophoretic cage which can be used to trap and hold particles at its center. If the particles moves away from the center of the cage, a resorting force acts on them towards the center. The MST results show that the ratio of the particle-particle interaction and dielectrophoretic forces decreases with increasing particle size. Therefore, larger particles move primarily under the action of the dielectrophoretic (DEP) force, especially in the high electric field gradient regions. Consequently, when the spacing between the electrodes is comparable to the particle size, instead of collecting on the same electrode by forming chains, they collect at different electrodes.

Wave–particle interaction and enhanced precipitation of charged particles

1985 ◽  
Vol 63 (4) ◽  
pp. 445-452
Author(s):  
R. N. Singh ◽  
R. Prasad
Keyword(s):  
Electric Fields ◽  
Geomagnetic Field ◽  
Pitch Angle ◽  
Electron Flux ◽  
Particle Interaction ◽  
Charged Particles ◽  
Lower Ionosphere ◽  
Wave Interaction ◽  
Whistler Wave ◽  
Inhomogeneity Parameter

In addition to parallel electric fields, the distortions in the geomagnetic field have been considered in the study of resonant whistler wave interaction with gyrating charged particles. Mead axisymmetric distortions in the geomagnetic field have been considered and new expressions for the inhomogeneity parameter, αd, have been obtained. Considering the diffusion of charged particles in pitch angle, the variation in the precipitating electron flux under varying magnetospheric conditions has been computed. The variation in the distribution of trapped charged particles is shown to play an important role in controlling the electron flux precipitated into the lower ionosphere.

scholarly journals Trapped Ion Quantum Computing Using Optical Tweezers and Electric Fields

2021 ◽  
Vol 127 (26) ◽  
Author(s):  
M. Mazzanti ◽  
R. X. Schüssler ◽  
J. D. Arias Espinoza ◽  
Z. Wu ◽  
R. Gerritsma ◽  
...  
Keyword(s):  
Quantum Computing ◽  
Optical Tweezers ◽  
Electric Fields ◽  
Trapped Ion

Anin situpowder diffraction cell for high-pressure hydrogenation experiments using laboratory X-ray diffractometers

2015 ◽  
Vol 48 (1) ◽  
pp. 79-84 ◽  
Author(s):  
Romain Moury ◽  
Klaus Hauschild ◽  
Wolfgang Kersten ◽  
Jan Ternieden ◽  
Michael Felderhoff ◽  
...  
Keyword(s):  
High Pressure ◽  
Powder Diffraction ◽  
Experimental Setup ◽  
X Ray Diffraction ◽  
X Ray ◽  
Elevated Pressures ◽  
Temperature Suitability ◽  
Proof Of Principle ◽  
Gas Pressures

Anin situdiffraction cell is presented which has been designed and constructed for in-house powder diffraction experiments under high gas pressures up to 30 MPa. For a proof of principle, thein situcell has been tested for several hydrogenation experiments under elevated pressures and temperatures. LaNi5was chosen as an example for hydrogenation, applying simultaneously 5.5 MPa H2pressure at a temperature of 423 K. For testing the high-pressure–temperature suitability of thein situcell, pressure–temperature experiments up to 14 MPa at 373 K were performed, studying the rehydrogenation of NaH and Al to NaAlH4. The experimental setup enables recording ofin situX-ray diffraction data on laboratory instruments with short data acquisition times at elevated hydrogen pressures and temperatures.

scholarly journals Fast gas heating in N 2 /O 2 mixtures under nanosecond surface dielectric barrier discharge: the effects of gas pressure and composition

2015 ◽  
Vol 373 (2048) ◽  
pp. 20140330 ◽  
Author(s):  
M. M Nudnova ◽  
S. V Kindysheva ◽  
N. L Aleksandrov ◽  
A. Yu Starikovskii
Keyword(s):  
Dielectric Barrier Discharge ◽  
Electric Fields ◽  
Barrier Discharge ◽  
Dielectric Barrier ◽  
Gas Heating ◽  
Electronically Excited ◽  
High Fraction ◽  
Surface Dielectric Barrier Discharge ◽  
High Electric Fields ◽  
Gas Pressures

The fractional electron power quickly transferred to heat in non-equilibrium plasmas was studied experimentally and theoretically in N 2 /O 2 mixtures subjected to high electric fields. Measurements were performed in and after a nanosecond surface dielectric barrier discharge at various (300–750 Torr) gas pressures and (50–100%) N 2 percentages. Observations showed that the efficiency of fast gas heating is almost independent of pressure and becomes more profound when the fraction of O 2 in N 2 /O 2 mixtures increases. The processes that contribute towards the fast transfer of electron energy to thermal energy were numerically simulated under the conditions considered. Calculations were compared with measurements and the main channels of fast gas heating were analysed at the gas pressures, compositions and electric fields under study. It was shown that efficient fast gas heating in the mixtures with high fraction of O 2 is due to a notable contribution of heat release during quenching of electronically excited N 2 states in collisions with O 2 molecules and to ion–ion recombination. The effect of hydrocarbon addition to air on fast gas heating was numerically estimated. It was concluded that the fractional electron power transferred to heat in air, as a first approximation, could be used to estimate this effect in lean and stoichiometric hydrocarbon–air mixtures.

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