Bulletin of the American Physical Society
64th Annual Meeting of the APS Division of Plasma Physics
Volume 67, Number 15
Monday–Friday, October 17–21, 2022; Spokane, Washington
Session BO07: Dusty Plasmas and Multiphase MediaLive Streamed
|
Hide Abstracts |
Chair: Saikat Chakraborty Thakur, Auburn University Room: 401 ABC |
Monday, October 17, 2022 9:30AM - 9:42AM |
BO07.00001: Ice Grain Structure and Growth in the Caltech Water-Ice Dusty Plasma Experiment André Nicolov, Paul M Bellan, Murthy Gudipati The Water-Ice Dusty Plasma Experiment at Caltech investigates the nucleation and dynamics of water-ice dust grains in a plasma. Capacitively-coupled RF electrodes are cooled to cryogenic temperatures, creating a weakly-ionized plasma with very cold neutral temperature. Water vapor injected into the plasma nucleates spontaneously to form quickly-growing ice grains. The ice grains are observed to have an elongated fractal structure reaching up to 700 microns in length, and are imaged with both a long-distance microscope camera and a laser diffraction scheme[1,2]. A Fourier Transform Infrared (FTIR) Spectrometer is being set up to characterize composition and phase of the solid dust grains, giving insight into the microstructure of the ice grains. These properties will be studied at a range of pressures and temperatures, determining the ice phase diagram and examining the transition between crystalline and amorphous ice grains. |
Monday, October 17, 2022 9:42AM - 9:54AM |
BO07.00002: Charge reversal and Coulomb expansion of a dust cloud in an afterglow plasma Neeraj Chaubey, John Goree The charging and Coulomb expansion of a dust cloud was studied experimentally, under afterglow conditions. A cloud of polymer microspheres was electrically levitated in a plasma under RF power, which was suddenly turned off. The dust particle charge, which was negative during steady plasma operation, reversed polarity in the afterglow due to a lack of electrons. We found that the magnitude of the positive charge was enhanced, to many thousands of elementary charges, due to ions streaming at their mobility-limited velocity, in the presence of a DC electric field. About 2 ms after switching off the RF power, the positively charged dust particles were the only charged species remaining in the chamber. They fell downward. We found that their fall could be slowed by reversing the electric field direction, at t = 2 ms, so that they could be observed for about 190 ms, before impact at the bottom of the chamber. During this extended observation time, the dust particle cloud expanded horizontally, due to the interparticle repulsion of like-charged particles. We quantified this expansion, and we found that at early times it is modeled accurately by the equation of state for a uniformly charged thin disk. |
Monday, October 17, 2022 9:54AM - 10:06AM |
BO07.00003: Nonequilibrium Structure for Shocks in a 2D Dusty Plasma Anton Kananovich, John Goree A single horizontal layer of negatively charged microspheres was levitated in a glow-discharge plasma, to make a 2D dusty plasma. Under steady conditions, the microspheres self-organized into a crystal, which had a hexagonal lattice, composed of equilateral triangles. This equilibrium condition was then disturbed by causing a compressional shock wave to propagate through it. The shock was generated by a moving exciter, which was a wire that had a negative bias, and moved at a supersonic speed while repelling nearby microspheres. Using a high-speed video camera viewing from above, we recorded images of the layer of microspheres, and we analyzed these images to obtain the x-y coordinates of microspheres. We then characterized the microstructure using Voronoi diagrams and polygon analysis. We found that as the hexagonal lattice deformed, under the considerable compression of the shock, the microspheres were no longer arranged in a lattice with hexagonal structure, but instead tended toward a trapezoidal lattice, with a nearly square symmetry. This nearly square lattice was observed within the shock layer, and immediately behind it. We note that a square lattice is never observed under steady conditions because it is unstable. |
Monday, October 17, 2022 10:06AM - 10:18AM |
BO07.00004: Experimental Observation of Coulomb Screening and Coulomb Acoustic Wave in Nanodusty Plasmas Bidyut Chutia, K. Avinash, Sumita K Sharma, Heremba Bailung Nanodusty plasma, composed of electrons, ions and nanometer sized dust grains, can result in a highly dense dusty plasma where the ratio of dust to ion densities i.e., Havnes parameter becomes very high, P»1. Due to high dust density, the nanodust particles float at a small potential resulting in a reduced average dust charge. In nanodusty plasmas, self-excited dust density waves dominate the cloud dynamics in most of the experimental scenarios. It has been shown theoretically by Avinash et al. [1],[2] that in high dust density regime, dust particles screen each other not by usual Debye screening but by a new screening mechanism called “Coulomb Screening”. This is shown to cause dust charge reduction. A characteristic scale length, λc2=1/4πndrd for Coulomb screening is obtained where nd and rd, are the dust density and dust radius, respectively. It is shown that Coulomb Screening gives rise to a new acoustic mode called Coulomb acoustic mode in high density nanodusty plasma. In this particular work, the observations and results of an experiment [3] on the propagation of a self-excited dust density wave under strong Havnes effect will be presented based on these theoretical predictions. For the parameters of the experiment, the Coulomb screening dominates over the Debye screening i.e., λc«λd. The dispersion relation is experimentally measured and compared with a theoretical dispersion which includes Debye as well as Coulomb screening. Based on this comparison the experimentally observed mode is identified as the “Coulomb Acoustic mode”. |
Monday, October 17, 2022 10:18AM - 10:30AM |
BO07.00005: Artificial voids in nanodusty plasmas at high Havnes parameter Franko Greiner, Ulrike Küst, Andreas Petersen Artificial voids are an interesting and frequently studied phenomenon in dusty plasmas [E. Thomas POP 2004, M. Klindworth RSE 2007, O. Arp PRE 2011, M. Schwabe NJP 2017]. Voids are created by projectiles shot into the dust cloud or by electrostatic probes. We present investigations of artificial voids created by electrostatic probes in nanodusty plasmas at high electron depletion (Havnes parameter >>1). Nanodusty plasmas are created by using a reactive argon acetylene plasma as a particle source. After switching off the acetylene a pristine nanodusty plasma of electrons, ions, and dust particles is created, the time of the acetylene flow determines the radius of the created dust particles. By variation of the probe voltage, the size of the void can be varied. As long as the probe void has not closed, a simple force balance explains the linear increase of the void radius for probe bias variations (dust repelling regime). However, the closure of the probe void destabilizes the whole nanodust cloud and strong dust streaming and the closure of the "natural" void are observed. The ability to use the force model to estimate the plasma potential and the consequences for credible Langmuir probe measurements in nanodusty plasmas at high Havnes Parameters will be discussed (see video https://youtu.be/Nmz2nR8uTrE or search youtube for "nanodustcloud"). |
Monday, October 17, 2022 10:30AM - 10:42AM |
BO07.00006: Short and Long-range Structural Deformation in Plasma Crystals Calvin Carmichael, Jorge A Martinez Ortiz, Parker J Adamson, Graeson Griffin, Lorin S Matthews, Truell W Hyde Complex plasma consists of micron-sized dust particles distributed in a weakly ionized gas. Within specific operating parameter regimes, combined with vertical and horizontal confinement, a 2D plasma crystal can be formed within a complex plasma. Torsions are a recently discovered, unique structure within such monolayer plasma crystals where dust particles form quasi-pairs that orbit outside the plane of the crystal due to decreases in power or pressure [1-3]. Torsions act as energy transfer agents through Coulomb interactions with surrounding particles, perturbing the hexagonal structure. At Baylor University, a GEC RF Reference Cell is being used to experimentally study the interaction between torsions and the dust particles within a lattice structure surrounding them. This will aid in understanding the maximum range of structural deformation caused by single and multiple torsions. This talk will discuss both torsion formation and their effect on the surrounding particles within the dust grain lattice using experimentally collected data employing high-speed cameras, laser fans, and particle tracking software. |
Monday, October 17, 2022 10:42AM - 10:54AM |
BO07.00007: Perturbation of Complex Plasma Crystals with Torsion Inclusions Parker J Adamson, Calvin Carmichael, Jorge A Martinez Ortiz, Graeson Griffin, Lorin S Matthews, Truell W Hyde Torsions are non-Hamiltonian features of some quasi 2D complex plasma crystals which occur when two dust particles vertically leave the plane of the crystal and begin to oscillate horizontally within a force cage formed by the remaining crystal lattice. Although, torsions have been studied as mechanisms within a complex plasma to achieve both energy transfer and phase transitions, little work has been done to carry out studies employing crystal perturbation of crystals with torsion inclusions. Such work is vital to clarifying how torsions affect the global dynamics of the surrounding crystal lattice. In this talk we present preliminary results of laser induced perturbation of such systems. |
Monday, October 17, 2022 10:54AM - 11:06AM |
BO07.00008: Fine-grained rims as probes of dusty protoplanetary environments Truell W Hyde, Graeson Griffin, Lorin S Matthews, Augusto Carballido During planet formation within circumstellar disks, dust coagulation is a critical step in the process, particularly in the growth of solids at the sub-millimeter to meter scales. Dust coatings, known as fine-grained rims (FGRs), have been observed on these bodies and are hypothesized to form from the accretion of nebular dust onto chondrules. Thus, FGRs are a key element in the formation of chondrite parent bodies, providing insight into their collisional history. Slow collision speeds are generally assumed necessary in order to lead to the formation of chondrule rims. As such, less experimental or theoretical attention has been given to the role that higher speed collisions or charged dust might play in the formation process. At least as important is the data such rims might provide on both the formation process as well as the surrounding nebula. This regime is important since Liffman (2019) recently suggested that higher-speed collisions might produce 'coatings' on chondrule surfaces as a result of the fragmentation of impinging micron-sized grains. We report on recent experimental results collected within a dusty environment for an operating parameter space designed to better establish the FGR formation process for particle / chondrule collisions. |
Monday, October 17, 2022 11:06AM - 11:18AM |
BO07.00009: Describing the ion wake formation and electric potential in the vicinity of multiple charged dust grains Katrina Vermillion, Rahul Banka, Alexandria Mendoza, Lorin S Matthews, Truell W Hyde Charged dust grains in a complex plasma are known to disturb the local environment through interactions with charged species in the plasma. This can lead to the formation of a region of enhanced ion density (an ion wake) which significantly modifies the form of the local electric potential. Under controlled conditions, dust grains have been experimentally observed to self-organize into interesting shapes, including single chains, zigzags, and twisted helices. Commonly used electric potential forms have been derived for regions far from isolated dust grains, but all fail to adequately describe the complex potential structure surrounding multiple charged dust grains as enhancements in the local ion density are not considered. The present study employs DRIAD, a GPU-accelerated molecular dynamics simulation, to model the ion flow and quantify the changes to the electric potential surrounding multiple charged dust grains. The charge on dust grains in the simulations influences the motions of the ions, and analysis of the highly resolved local ion number density provides the basis for a detailed description of the resulting electric potential. |
Monday, October 17, 2022 11:18AM - 11:30AM |
BO07.00010: Laser-stimulated photodetachment of electrons from metal nanoparticles in plasma Mikhail N Shneider, Yevgeny Raitses, Shurik Yatom We study the laser-stimulated photodetachment of electrons (LSPD) [1,2] from dust particles in plasma. Specifically, we developed a theory of the LSPD with applications to spherical metal nanoparticles immersed in the plasma. The charging of nanoparticles in plasma leads to the appearance of an additional electric field, leading to a change in the potential barrier at the particle boundary and, consequently, a change in the effective work function, due to the Schottky effect. In this case, the critical wavelength of the laser (the red border of the photoelectric effect) depends not only on the work function and size but also on the charge of the nanoparticles. Our theory predicts that the smaller the size of the nanoparticles, the stronger the shift of the red boundary of the photoelectric effect. Considered effects are important for selecting the LSPD laser wavelength and analysis of measured results. |
Monday, October 17, 2022 11:30AM - 11:42AM |
BO07.00011: Bispectral analysis of nonlinear mixing in dusty plasma Ajaz A Mir, Sanat K Tiwari, Abhijit Sen We verified nonlinear mixing (NLM) in a dusty plasma medium using the forced Korteweg-de Vries (fKdV) model in a weakly nonlinear dynamical regime [1, 2]. The mixing modes are excited due to the nonlinear coherent three-wave interaction between the natural KdV mode and its harmonics with the external forcing. The power spectrum is the primary diagnostic tool used to capture the information of excited modes. However, the power spectral analysis doesn’t capture the phase information of the excited modes. Hence, it can’t distinguish between the coherent and incoherent modes of the fKdV model, i.e., we cant confirm the origin of modes due to mixing or some other spurious origin. To resolve this ambiguity, the phase information is captured by calculating the triple correlation of the time series of fKdV and the technique is known as bispectral analysis [3]. The bispectral analysis easily discriminates between the coherent and incoherent origin of modes obtained in the mixing profile. |
Monday, October 17, 2022 11:42AM - 11:54AM |
BO07.00012: Fate of Convection Cells in 2D Yukawa Liquids via Molecular Dynamics Simulations Pawandeep Kaur, Rajaraman Ganesh Convection cells are found in a diverse variety of natural as well as technological systems such as Sun, planetary atmosphere, Earth’s mantle, oceans, tea kettle, Tokamaks etc. In view of their ubiquity, several attempts have been made to understand the stability of convection cells in conventional liquids using 2D hydrodynamic studies [1]. |
Monday, October 17, 2022 11:54AM - 12:06PM |
BO07.00013: Redistribution of Kinetic Energy in a Microgravity Complex (Dusty) Plasma Lori C McCabe, Edward Thomas, Uwe Konopka, Saikat Chakraborty Thakur, Jeremiah D Williams, Mikhail Pustylnik, Hubertus Thomas In the presence of gravity, the micron-sized charged dust particles in a complex plasma are compressed to thin layers, but under microgravity conditions, such as the Plasma Kristall-4 (PK-4) experiment on the International Space Station (ISS), the particles fill the plasma volume which allows the study of a 3D multi-particle system. When dust particles are injected into a dc glow discharge plasma they flow along an axial electric field until stopped by periodic oscillations of the electric field (polarity switching). This oscillation creates a change in the spatial ordering and thermal state of the particle system. |
Monday, October 17, 2022 12:06PM - 12:18PM |
BO07.00014: Particle trapping enables the dusty plasma synthesis of highly monodisperse nanocrystals Julian Held, Mohammadali Eslamisaray, Uwe R Kortshagen Dusty plasmas are finding increasing attention for the synthesis of nanoparticles that are difficult or impossible to produce with other synthesis methods. Recent research has shown that temporary particle trapping plays an important role acting as a “size filter” in the synthesis of sub-10 nm nanocrystals in tubular laminar flow plasma reactors. In this process, small particles are trapped by the electrostatic force, which scales linearly with the particle radius, and grow through the surface deposition of precursor until the gas drag force, which scales with the square of the particle radius, overcomes the electrostatic force. This causes particle to leave the plasma after reaching a threshold size at which electrostatic and drag force balance. Here, we demonstrate how the concept of size-filtering through temporary electrostatic trapping can be expanded to the synthesis of highly monodisperse nanoparticles ranging from 30-200 nm with standard deviations of the size distribution of just a few nanometers. We discuss that in this process, particle trapping is indeed two-dimensional, involving both axial and radial transport. We propose that the threshold for particle de-trapping is the result of the competition of the electrostatic, thermophoretic, and drag forces. |
Monday, October 17, 2022 12:18PM - 12:30PM |
BO07.00015: Quasi-Localized charge approximation (QLCA) approach for the nonlinear structures in strongly coupled Yukawa systems Prince Kumar, Devendra Sharma Nonlinear excitations in a strongly coupled dusty plasma system [1] are investigated within the Quasi-Localized Charged Approximation QLCA framework [2]. A QLCA based model is considered allowing to account for the finite configurational localization of the strongly coupled dust species addressing their nonlinear regime of excitation governed by the rather dominating deterministic isothermal dust compressibility mechanism, than the effective pressure or kinetic randomness effects. Distinct but physically concurrent representations of finite localization effect in the long wavelength limit are adopted suitable for analytic and numerical approaches, respectively, to the nonlinear spatiotemporal solutions of the model. The results predict increment in both the amplitude and width of a solitary wave when strong coupling with finite localization effect is admitted. This behavior is distinct from the linear and nonlinear excitations produced when strong coupling is accounted for by its effective representation which excludes explicit configurational localization of highly charged dust species [2,3] as essential in sufficiently strong coupling limit. Detailed spatiotemporal evolution of the nonlinear solitary solutions is presented and quantitatively validated. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700