arXiv subjects

Surabhi Jaiswal

Publications and source records attributed to Surabhi Jaiswal.

9 recordsLinked to original sources

arXiv2026

Investigation of Shock Wave Dynamics in Complex Plasma via Computational Modelling

Piston-driven shock waves in dusty plasma monolayers have been observed experimentally and studied using molecular dynamics (MD) simulations. However, previous MD simulations were restricted to strictly two-dimensional geometries with periodic or reflecting boundaries and therefore could not capture the out-of-plane buckling of microparticles observed experimentally under shock compression. We present three-dimensional MD simulations of a piston-driven shock in a two-dimensional dusty plasma. The model incorporates finite-harmonic vertical confinement, fixed boundaries, Epstein drag and a microparticle size distribution matched to previous experiments. The simulations recover the experimentally observed linear scaling between the shock and piston Mach numbers and, to the best of our knowledge, reproduce, for the first time in MD, shock-induced buckling of the monolayer. These results bridge a long-standing gap between laboratory observations and simulations of two-dimensional dusty plasma shocks, and provide a validated framework for investigating out-of-plane and wake-mediated shock physics in strongly coupled systems.

physics.plasm-ph↗

arXiv2026

Direct experimental measurement of ion properties in extreme plasma condition

We have demonstrated Laser Induced Fluorescence (LIF) in a Capacitively Coupled Plasma (CCP) discharge to directly measure the most crucial ion properties at a discharge regime suitable for a broad range of plasma research related to plasma processing and dusty plasma investigations that has been impossible for many years. The ion flow measurements in the presence and absence of dust particles show that ions move much faster directionally than expected from thermal motion, with reductions observed in the presence of dust particles. Ion temperatures are also found to exceed room temperature, contrary to a common assumption in the dusty plasma community. These findings represent a significant advancement in experimental plasma research, providing vital information to refine ion-driven process models with insights that span multiple research fields.

physics.plasm-ph↗

arXiv2026

Investigating Solid-Fluid Phase Coexistence in DC Plasma Bilayer Crystals: The Role of Particle Pairing and Mode Coupling

This article presents a detailed investigation of solid-fluid phase coexistence in a bilayer dusty plasma crystal subjected to varying confinement ring bias voltages in a DC glow discharge argon plasma. Melamine formaldehyde particles were employed to form a stable, hexagonally ordered bilayer crystal within a confinement ring electrically isolated from the grounded cathode. By systematically adjusting the confinement ring bias, a distinct phase coexistence emerged characterized by a fluid-like melted core surrounded by a solid crystalline periphery. Crucially, analysis of the phonon spectra revealed frequency shifts that deviate significantly from the predictions of classical monolayer Mode-Coupling Instability (MCI) theory. Stability analysis further demonstrated that dynamic interlayer particle pairing and the associated increase in non-reciprocal interaction strength are strongly correlated with the onset of structural destabilization. These findings highlight previously underappreciated mechanisms driving the melting transition in bilayer dusty plasmas, offering a more comprehensive understanding of phase behavior in complex plasma systems. The results underscore the importance of interlayer coupling and confinement effects in tuning structural transitions.

physics.plasm-ph↗

arXiv2025

Large Errors in Kinetic Temperature Measurements Using Particle Tracking Velocimetry

We report on random errors in kinetic temperature measurements due to finite spatial resolution in particle tracking velocimetry. Using simulated data, we isolate the error caused by finite spatial resolution from other sources of uncertainty, such as particle acceleration and particle mismatch. A sample of particle velocities is generated from a Maxwellian distribution at a prescribed kinetic temperature. Particle positions are assigned randomly and discretized to match a prescribed spatial resolution. Velocities are reconstructed using the two-frame tracking method, and the resulting kinetic temperature is calculated and compared to the true kinetic temperature. Results show that under typical experimental conditions, the uncertainty in particle positions propagates into large errors in the velocity distribution and the measured kinetic temperature. We find that this might introduce errors ranging from tens of percent at high kinetic temperatures ($\sim 10$~eV) to thousands of percent at low temperatures ($\sim 0.1$~eV).

physics.plasm-ph↗

arXiv2025

Critical role of the motor density and distribution on polar active polymers

Polar polymer activity is a fundamental mechanism behind a large number of cellular dynamical processes. The number and location of the active sites on the polymer backbone play a central role in their dynamics and conformational properties. Globular conformations for high motor densities change to stretched ones for the more realistic moderate or low density of motors, with a self-propelled polymer velocity non-monotonically related to the motor density. A small difference in the position of the first motor, or the motor distribution, can also dramatically modify the polymer typical conformations

cond-mat.soft↗

arXiv2024

Diffusiophoretic Brownian dynamics: characterization of hydrodynamic effects for an active chemoattractive polymer

The phoretic Brownian dynamics method is shown here to be an effective approach to simulate the properties of colloidal chemophoretic based systems. The method is then optimized to allow for the comparison with results from multiparticle collision dynamics, a hydrodynamic method with explicit solvent, which can also be employed in the case of chemoattractive polymers. In order to obtain a good match of the conformational equilibrium properties of the models without and with explicit solvent, we propose a modified version of the phoretic Brownian dynamics accounting for the explicit solvent induced swelling. In the presence of activity, chemoattractive polymers show a transition to a compact globular state and hydrodynamics have a non-trivial influence in the polymer collapse times. The phoretic Brownian method can then be applied to much longer polymers, which allows the observation of a non-monotonous growth of both, the radius of gyration and the relaxation time with polymer length, for such chemoattractive active polymers.

cond-mat.soft↗

arXiv2023

Kinetic Modeling Analysis of Ar Addition to Atmospheric Pressure N2-H2 Plasma for Plasma-Assisted Catalytic Synthesis of NH3

Zero-dimensional kinetic modeling of atmospheric pressure Ar-N2-H2 nonthermal plasma was carried out to gain mechanistic insights into ammonia formation during plasma-assisted catalysis of ammonia synthesis. The kinetic model was developed for a coaxial dielectric barrier discharge (DBD) quartz wool-packed bed reactor operating at near room temperature using a kHz-frequency plasma source. With 30% Ar mixed in a 1:1 N2-H2 plasma at 760 Torr, we find that NH3 production is dominated by Eley-Rideal (E-R) surface reactions, which heavily involve surface NHx species derived from N and H radicals in the gas phase, while the influence of excited N2 molecules is negligible. This is contrary to the commonly proposed mechanism that excited N2 molecules created by Penning excitation of N2 by Ar (4s) and Ar(4p) plays a significant role in assisting NH3 formation. Our model shows that the enhanced NH3 formation upon Ar dilution is unlikely due to the interactions between Ar and H species, as excited Ar atoms have a weak effect on H radical formation through H2 dissociation compared to electrons. We find that excited Ar atoms contribute to 28% of the N radical production in the gas phase via N2 dissociation, while the rest is dominated by electron-impact dissociation. Furthermore, Ar species play a negligible role in the product NH3 dissociation. N2 conversion sensitivity analyses were carried out for electron density (ne) and reduced electric field (E/N), and contributions from Ar to gas-phase N radical production were quantified. The model can provide guidance on potential reasons for observing enhanced NH3 formation upon Ar dilution in N2-H2 plasmas beyond changes to the discharge characteristics.

physics.plasm-ph↗

arXiv2020

Measurement of temperature of a dusty plasma from configuration

A new method called `Configurational Temperature' is introduced in the context of dusty plasma, where the temperature of the dust particles, submerged in the plasma, can be measured directly from the positional information of the individual dust particles and the interaction potential between the dust grains. This method does not require the velocity information of individual particles which is a key parameter to measure the dust temperature in the conventional method. The technique is initially tested using two dimensional OpenMP parallel Molecular Dynamics and Monte-Carlo simulation and then compared with the temperature evaluating from the experimental data. The experiments have been carried out in Dusty plasma experimental (DPEx) device where a two dimensional stationary plasma crystal of melamine formaldehyde particles is formed in the cathode sheath of a DC glow discharge argon plasma. The dust kinetic temperature is calculated using standard PIV technique at different pressures. The simulation results matches well with the experimental data at relatively higher pressures where the dust particles arranged into crystalline state or in a strongly coupled fluid state. An extended simulation results for three dimensional case is also presented which can be employed for the temperature measurement of three dimensional dust crystal in laboratory devices.

physics.plasm-ph↗

arXiv2016

Experimental observation of precursor solitons in a flowing complex plasma

The excitation of precursor solitons ahead of a rapidly moving object in a fluid, a spectacular phenomenon in hydrodynamics that has often been observed ahead of moving ships, has surprisingly not been investigated in plasmas where the fluid model holds good for low frequency excitations such as ion acoustic waves. In this paper we report the first experimental observation of precursor solitons in a flowing dusty plasma. The nonlinear solitary dust acoustic waves (DAWs) are excited by a supersonic mass flow of the dust particles over an electrostatic potential hill. In a frame where the fluid is stationary and the hill is moving the solitons propagate in the upstream direction as precursors while wake structures consisting of linear DAWs are seen to propagate in the downstream region. A theoretical explanation of these excitations based on the forced Korteweg-deVries model equation is provided and their practical implications in situations involving a charged object moving in a plasma are discussed.

physics.plasm-ph↗