arXiv subjects

Mangilal Choudhary

Publications and source records attributed to Mangilal Choudhary.

At least 19 recordsLinked to original sources

arXiv2026

Activated carbon-assisted anionic dye decomposition using a dual-liquid post-double dielectric barrier discharge plasma reactor

Non-thermal Plasma (NTP) technology, including the Dielectric Barrier Discharge (DBD) reactor, has emerged as an effective advanced oxidation process (AOP) for treating persistent organic pollutants in industrial wastewater. Based on this objective, a dual-liquid dielectric-barrier-discharge plasma reactor was built and used to degrade a ternary anionic dye mixture comprising Reactive Red 120, Congo Red, and Methyl Orange in its post-discharge configuration. The adjustable length of the outer liquid electrode (grounded) provides flexibility in controlling the discharge length and cooling, thereby achieving higher degradation efficiency and greater reactor stability. The conducting-liquid high-voltage electrode (a dielectric tube filled with a conductive solution) helps mitigate metal corrosion and oxidation caused by reactive species in the discharge zone. A detailed study of the degradation of ternary anionic dye mixtures (simulated dye wastewater samples) in the presence of activated carbon (AC) was performed to explore the potential applications of post-discharge treatment. The activated carbon (granules) enhances the degradation rate of ternary anionic dye mixtures in basic solutions rather than in acidic or neutral solutions. A comparative study of the degradation reaction kinetics of the ternary anionic dye mixtures in acidic and basic solutions was conducted after analyzing UV-Vis absorption spectra. The role of other parameters, such as solution pH, the mass and size of AC particles, dye concentrations, and AC reuse, was investigated in relation to degradation efficiency. The degradation mechanism was elucidated by the formation of strong oxidizer (hydroxyl radicals) on the surface of activated carbon during post-discharge treatment. However, in acidic or neutral anionic dye solutions, the degradation mechanism was dominated by ozone.

physics.plasm-ph↗

arXiv2026

Transient spark dielectric barrier post-discharge plasma reactor with a liquid electrode for dye degradation: A primary study

The potential application of non-thermal plasma in treating textile industrial wastewater motivates researchers to develop innovative techniques at a laboratory scale to achieve the goal of wastewater mineralization. In line with this objective, a dielectric barrier post-discharge plasma reactor with a liquid electrode has been built for the study of synthetic dye degradation. The plasma reactor was optimized by altering various operating conditions to achieve a higher degradation efficiency at given discharge conditions. The reaction kinetics of crystal violet degradation were studied, and the same plasma reactor was tested for other synthetic dyes (wastewater model samples). The results suggest that the proposed dielectric barrier post-discharge plasma reactor may offer a promising solution for treating dye effluents from the textile industry.

physics.plasm-ph↗

arXiv2025

Experimental study of argon gas breakdown with symmetric and asymmetric electrode configurations

Paschen law relates the breakdown voltage of a gas to the product of gas pressure and inter-electrode distance, predicting a characteristic minimum voltage at a specific pd value. In this study, the role of electrode configurations (symmetric and asymmetric) and inter-electrode spacing on the gas breakdown processes (or Paschen Law) is examined. Numerous sets of experiments are performed with both symmetric and asymmetric electrode configurations of different sizes to obtain Paschen curves at different inter-electrode distances. The experimentally obtained Paschen's curves for different electrode configurations are fitted using a proposed modified empirical relation for breakdown voltage, incorporating variable power-law dependencies and fitting parameters to better capture the observed deviations. Upon closer inspection, we observed that the breakdown voltage and the corresponding pd value are influenced by both electrode configurations and the inter-electrode discharge gap. The variation in breakdown voltage and pd minima for different electrode configurations is explained by analyzing the electric field distributions between the electrodes (cathode and anode) for an applied voltage.

physics.plasm-ph↗

arXiv2024

A review on the Vortex and Coherent Structures in Dusty Plasma Medium

Dusty plasma is an admixture of electrons, ions, and massive charged solid particles of sub-micron to micron-sized in the background of neutral gas. The dust grain medium exhibits fluid (liquid) as well as solid-like characteristics at different background plasma conditions. It supports various linear and non-linear dynamical structures because of the external perturbation and internal instabilities. The vortical or coherent structure in the dusty plasma medium is a kind of self-sustained dynamical structure that is formed either by instabilities or external forcing. In this review article, the author discusses the past theoretical, experimental, and computational investigations on vortical and coherent structures in unmagnetized as well as in magnetized dusty plasma. The possible mechanisms to form vortices in dust grain medium are discussed in detail. The studies on the evolution of vortices and their correlation with turbulence are also reviewed.

physics.plasm-ph↗

arXiv2023

Magnetized dusty plasma: On issues of its complexity and magnetization of charged dust particles

It is possible to excite various linear and non-linear low-frequency modes in dusty plasma which is an admixture of electrons, ions, gas atoms, and negatively charged solid particles. The experimental as well as theoretical study of these low-frequency dynamical modes in dusty plasma is very complex because of the involvement of dynamics of electrons, ions, and neutrals. If the external magnetic field is introduced to dusty plasma then the dynamics of it will be more complex. The complexity of magnetized dusty plasma where plasma species are magnetized is discussed by keeping the experimental observations in magnetized dusty plasma devices in mind. The requirement of theoretical modeling, as well as computation experiments in understanding the dynamics of dusty plasma in the presence of a strong magnetic field, is highlighted in the context of experimental findings. The major challenges to magnetizing charged massive particles in experiments and some expected solutions are discussed in this report.

physics.plasm-ph↗

arXiv2023

Plasma Agriculture: A green technology to attain the sustainable agriculture goal

The agriculture sector has many issues such as reductions of agricultural lands, growing population, health issues arising due to the use of synthetic fertilizers and pesticides, reduction in soil health due to extreme use of synthetic chemicals during farming, etc. The quality and quantity of foods required for living things are affected by many factors like scarcity of nutrient-rich soils, lack of suitable fertilizers, harmful insects and bugs, climate change, etc. There is a requirement to supply the proper nutrients to plants/crops for obtaining a high crop yield. Synthetic chemical fertilizers provide nutrients (macro and micro) to plants for their growth and development but the excess use of them is not good for a healthy lifestyle as well as for the environment. In recent years, non-thermal plasma (NTP) is considered as an advanced green technology for enhancing productivity in agriculture sectors. In this report, we provided the details of nutrients and their functions in the growth and development of plants/crops. How plasma technology can resolve many future challenges in the agriculture sector is discussed in detail. A few experiments on seed germination and plant growth (root and shoot length) were performed in the laboratory to explore the effect of plasma-activated water on the growth and development of plants. These primary results demonstrate the great potential of plasma technology in the agriculture sector.

physics.plasm-ph↗

arXiv2023

Degradation of methylene blue dye as wastewater pollutant by atmospheric pressure plasma: A comparative study

The industrial application of non-thermal plasma has been a research field in the last few years. One of the potential applications of non-thermal plasma is in treating dye effluents of textiles industries which are considered as one of the environmental pollutants. Before scaling up plasma technology at the industrial level, it is required to understand the interaction of non-thermal plasma with a synthetic dye-containing solution in laboratory experiments. A detailed comparative study of MB dye degradation using an atmospheric pressure air plasma (corona discharge) source is carried out in this report. The results are qualitatively discussed in line with the available theoretical and experimental background of plasma-water interaction.

physics.plasm-ph↗

arXiv2021

Response of the low pressure hot-filament discharge plasma to a positively biased auxiliary disk electrode

In steady-state, the plasma loss rate to the chamber wall is balanced by the ionization rate in the hot-filament discharges. This balance in the loss rate and ionization rate maintains the quasi--neutrality of the bulk plasma. In this report, we have studied the properties of bulk plasma in the presence of an auxiliary (additional) biased metal disk, which is working as a sink, in low-pressure helium plasma. A single Langmuir probe and emissive probe are used to characterize the plasma for various biases (positive and negative) to the metal disk, which was placed along the discharge axis inside the plasma. It is observed that only a positively biased disk increases the plasma potential, electron temperature, and plasma density. Moreover, the plasma parameters remain unaltered when the disk is negatively biased. The observed results for two different-sized positively metal disks are compared with an available theoretical model and found an opposite behavior of plasma density variation with the disk bias voltages at given discharge condition. The role of the primary energetic electron population in determining the plasma parameters is discussed. These experimental results are qualitatively explained on the basis of electrostatic confinement arising due to the loss of electrons to a biased metal disk electrode.

physics.plasm-ph↗

arXiv2021

Perspective: The dusty plasma experiments a learning tool for physics graduate students

The plasma is an ionized gas that responses collectively to any external (or internal) perturbations. Introducing micron-sized solid dust grains into plasma makes it more interesting. The solid grains acquire large negative charges on their surface and exhibits collective behavior similar to the ambient plasma medium. Some remarkable features of the charged dust grain medium (dusty plasma) allow us to use it as a model system to understand some complex phenomena at a microscopic level. In this perspective paper, the author highlights the role of dusty plasma experiments as a learning tool at undergraduate and post-graduate physics programs. The students could have great opportunities to understand some basic physical phenomena as well as to learn many advanced data analysis tools and techniques by performing dusty plasma experiments. How a single dusty plasma experimental device at a physics laboratory can help undergraduate and post-graduate students in the learning process is discussed.

physics.ed-ph↗

arXiv2020

Comparative Study of the Surface Potential of Magnetic and Non-magnetic Spherical Objects in a Magnetized RF Discharge Plasma

We report measurements of the time-averaged surface floating potential of magnetic and non-magnetic spherical probes (or large dust particles) immersed in a magnetized capacitively coupled discharge. In this study, the size of the spherical probes is taken greater than the Debye length. The surface potential of a spherical probe first increases, i.e. becomes more negative at low magnetic field (B $<$ 0.05 T), attains a maximum value and decreases with further increase of the magnetic field strength (B $>$ 0.05 T). The rate of change of the surface potential in the presence of a B-field mainly depends on the background plasma and types of material of the objects. The results show that the surface potential of the magnetic sphere is higher (more negative) compared to the non-magnetic spherical probe. Hence, the smaller magnetic sphere collects more negative charges on its surface than a bigger non-magnetic sphere in a magnetized plasma. The different sized spherical probes have nearly the same surface potential above a threshold magnetic field (B $>$ 0.03 T), implicating a smaller role of size dependence on the surface potential of spherical objects. The variation of the surface potential of the spherical probes is understood on the basis of a modification of the collection currents to their surface due to charge confinement and cross-field diffusion in the presence of an external magnetic field.

physics.plasm-ph↗

arXiv2020

Low--Temperature Plasma Technology: Impact on Indian Rural Life

The low temperature plasma technology has been emerged as an alternative environmental friendly technology that has a potential to replace the traditional technologies in various sectors such as textile industries, agriculture, food industries and waste water treatment. The future prospective of the low temperature plasma technology on the life of rural Indians has been discussed in this brief report.

physics.pop-ph↗

arXiv2020

Rotational properties of annulus dusty plasma in a strong magnetic field

The collective dynamics of annulus dusty plasma formed between a co-centric conducting (non-conducting) disk and ring configuration is studied in a strongly magnetized radio-frequency (rf) discharge. A superconducting electromagnet is used to introduce a homogeneous magnetic field to the dusty plasma medium. In absence of the magnetic field, dust grains exhibit thermal motion around their equilibrium position. The dust grains start to rotate in anticlockwise direction with increasing magnetic field (B $>$ 0.02 T), and the constant value of the angular frequency at various strengths of magnetic field confirms the rigid body rotation. The angular frequency of dust grains linearly increases up to a threshold magnetic field (B $>$ 0.6 T) and after that its value remains nearly constant in a certain range of magnetic field. Further increase in magnetic field (B $>$ 1 T) lowers the angular frequency. Low value of angular frequency is expected by reducing the width of annulus dusty plasma or the input rf power. The azimuthal ion drag force due to the magnetic field is assumed to be the energy source which drives the rotational motion. The resultant radial electric field in the presence of magnetic field determines the direction of rotation. The variation of floating (plasma) potential across the annular region at given magnetic field explains the rotational properties of the annulus dusty plasma in the presence of magnetic field.

physics.plasm-ph↗

arXiv2020

3-Dimensional Dusty Plasma in a Strong Magnetic Field: Observation of Rotating Dust Tori

The paper reports on the dynamics of a 3-dimensional dusty plasma in a strong magnetic field. An electrostatic potential well created by a conducting or non-conducting ring in the rf discharge confines the charged dust particles. In the absence of the magnetic field, dust grains exhibit a thermal motion about their equilibrium position. As the magnetic field crosses a threshold value (B $>$ 0.02 T), the edge particles start to rotate and form a vortex in the vertical plane. At the same time, the central region particles either exhibit thermal motion or $\vec{E} \times \vec{B}$ motion in the horizontal plane. At B $>$ 0.15 T, the central region dust grains start to rotate in the opposite direction resulting in a pair of counter-rotating vortices in the vertical plane. The characteristics of the vortex pair change with increasing the strength of the magnetic field (B $\sim$ 0.8 T). At B $>$ 0.8 T, dust grains exhibit very complex motion in the rotating torus. The angular frequency variation of rotating particles indicates a differential or sheared dust rotation in a vortex. The angular frequency increases with increasing the magnetic field from 0.05 T to 0.8 T. The ion drag force and dust charge gradient along with the E-field are considered as possible energy sources for driving the edge vortex flow and central region vortex motion, respectively. The directions of rotation also confirm the different energy sources responsible for the vortex motion.

physics.plasm-ph↗

arXiv2019

Influence of External Magnetic Field on Dust$-$Acoustic Waves in a Capacitive RF Discharge

This paper reports experiments on self$-$excited dust acoustic waves (DAWs) and its propagation characteristics in a magnetized rf discharge plasma. The DAWs are spontaneously excited in dusty plasma after adding more particles in the confining potential well and found to propagate in the direction of streaming ions. The spontaneous excitation of such low-frequency modes is possible due to the instabilities associated with streaming ions through the dust grain medium. The background E-field and neutral pressure determine the stability of excited DAWs. The characteristics of DAWs strongly depend on the strength of external magnetic field. The magnetic field of strength B $<$ 0.05 T only modifies the characteristics of propagating waves in dusty plasma at moderate power and pressure, P = 3.5 W and p = 27 Pa respectively. It is found that DAWs start to be damped with increasing the magnetic field beyond B $>$ 0.05 T and get completely damped at higher magnetic field B $\sim$ 0.13 T. After lowering the power and pressure to 3 W and 23 Pa respectively, the excited DAWs in the absence of B are slightly unstable. In this case, the magnetic field only stabilizes and modifies the propagation characteristics of DAWs while the strength of B is increased up to 0.1 T or even higher. The modification of the sheath electric field where particles are confined in the presence of the external magnetic field is the main cause of the modification and damping of the DAWs in a magnetized rf discharge plasma.

physics.plasm-ph↗

arXiv2017

Collective dynamics of large aspect ratio dusty plasma in an inhomogeneous plasma background: Formation of the co--rotating vortex series

In this paper, the collective dynamics of the large aspect ratio dusty plasma is studied over a wide range of discharge parameters. An inductively coupled diffused plasma, which creates an electrostatic trap to confine the negatively charged grains, is used to form a large volume (or large aspect ratio) dusty plasma at low pressure. For introducing the dust grains into the potential well, a unique technique using a secondary DC glow discharge plasma is employed. The dust dynamics is recorded in a 2-dimension (2D) plane at a given axial location. The dust fluid exhibits wave like behavior at low pressure (p < 0.06 mbar) and high rf power (P > 3 W). The mixed motion, waves and vortices, are observed at an intermediate gas pressure(p = 0.08 mbar) and low power (P < 3 W). Above the threshold value of gas pressure (p > 0.1 mbar), the clockwise and anti-clockwise co-rotating vortex series are observed on the edges of the dust cloud, whereas the particles in central region show the random motion. These vortices are only observed above a threshold width of the dust cloud. The streaming ions are considered the available free energy source to excite the waves in dust grain medium. The occurrence of the co-rotating vortices is understood on the basis of the charge gradient of dust particles which is orthogonal to the gravity. The charge gradient is a consequence of the plasma inhomogeneity from the central region to the outer edge of dust fluid. Since, a vortex has the characteristic size in the dissipative medium; therefore, a series of the co-rotating vortex on the both sides of dusty plasma is observed. The experimental results on the vortex formation and its multiplicity are compared to an available theoretical model and are found to be in close agreement.

physics.plasm-ph↗

arXiv2017

Experimental observation of self excited co--rotating multiple vortices in a dusty plasma with inhomogeneous plasma background

We report an experimental observation of multiple co--rotating vortices in a extended dust column in the background of non--uniform diffused plasma. Inductively coupled RF discharge is initiated in the background of argon gas in the source region which later found to diffuse in the main experimental chamber. A secondary DC glow discharge plasma is produced to introduce the dust particles into the plasma. These micron sized poly-disperse dust particles get charged in the plasma environment and transported by the ambipolar electric field of the diffused plasma and found to confine in the potential well, where the resultant electric field of the diffused plasma (ambipolar E--field) and glass wall charging (sheath E--field) hold the micron sized particles against the gravity. Multiple co--rotating (anti--clockwise) dust vortices are observed in the dust cloud for a particular discharge condition. The transition from multiple to single dust vortex is observed when input RF power is lowered. Occurrence of these vortices are explained on the basis of the charge gradient of dust particles which is orthogonal to the ion drag force. The charge gradient is a consequence of the plasma inhomogeneity along the dust cloud length. The detailed nature and the reason for multiple vortices are still under investigation through further experiments, however, preliminary qualitative understanding is discussed based on characteristic scale length of dust vortex. There is a characteristic size of the vortex in the dusty plasma so that multiple vortices is possible to form in the extended dusty plasma with inhomogeneous plasma background. The experimental results on the vortex motion of particles are compared with a theoretical model and found some agreement.

physics.plasm-ph↗

arXiv2016

Propagation characteristics of dust$-$acoustic waves in presence of a floating cylindrical object in the DC discharge plasma

The experimental observation of the self$-$excited dust acoustic waves (DAWs) and its propagation characteristics in the absence and presence of a floating cylindrical object are investigated. The experiments are carried out in a direct current (DC) glow discharge dusty plasma in the background of argon gas. Dust particles are found levitated at the interface of plasma and cathode sheath region. The DAWs are spontaneously excited in the dust medium and found to propagate in the direction of ion drift (along the gravity) above a threshold discharge current at lower pressure. The excitation of such low frequency wave is a result of the ion--dust streaming instability in the dust cloud. The characteristics of the propagating dust acoustic wave get modified in presence of a floating cylindrical object of radius larger than the dust Debye length. Instead of propagating in the vertical direction, the DAWs are found to propagate obliquely in presence of the floating object (kept either vertically or horizontally). In addition, horizontally aligned floating object gives rise to form a wave structure in the cone shaped dust cloud in the sheath region. The change in the propagation characteristics of DAWs are explained on the basis of modified potential (or electric field) distribution, which is a consequence of coupling of sheaths formed around the cylindrical object and the cathode.

physics.plasm-ph↗

arXiv2016

Transport and trapping of dust particles in a potential well created by inductively coupled diffused plasma

A versatile linear dusty (complex) plasma device is designed to study the transport and dynamical behavior of dust particles in a large volume. Diffused inductively coupled plasma is generated in the background of argon gas. A novel technique is used to introduce the dust particles in the main plasma by striking a secondary direct current (DC) glow discharge. These dust particles are found to get trapped in an electrostatic potential well which is formed due to the combination of the ambipolar electric field caused by diffusive plasma and the field produced by the charged glass wall of the vacuum chamber. According to the requirements, the volume of the dust cloud can be controlled very precisely by tuning the plasma and discharge parameters. The present device can be used to address the underlying physics behind the transport of dust particles, self excited dust acoustic waves and instabilities. The detailed design of this device, plasma production and characterization, trapping and transport of the dust particle and some of the preliminary experimental results are presented.

physics.plasm-ph↗