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U. Sarma

Bio: U. Sarma is an academic researcher from Kaziranga University. The author has contributed to research in topics: Magnetic field & Force field (physics). The author has an hindex of 1, co-authored 1 publications receiving 1 citations.

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TL;DR: In this article, a Langevin dynamics simulation of a pair-ion plasma (PIP) system was performed in the presence of an external magnetic field, and the phase diagram obtained distinguishing the no-lane and lane states was systematically determined from a study of various Coulomb coupling parameter values.
Abstract: Lane formation dynamics in externally driven pair-ion plasma (PIP) particles is studied in the presence of external magnetic field using Langevin dynamics (LD) simulation. The phase diagram obtained distinguishing the no-lane and lane states is systematically determined from a study of various Coulomb coupling parameter values. A peculiar lane formation-disintegration parameter space is identified; lane formation area extended to a wide range of Coulomb coupling parameter values is observed before disappearing to a mixed phase. The different phases are identified by calculating the order parameter. This and the critical parameters are calculated directly from LD simulation. The critical electric field strength value above which the lanes are formed distinctly is obtained, and it is observed that in the presence of the external magnetic field, the PIP system requires a higher value of the electric field strength to enter into the lane formation state than that in the absence of the magnetic field. We further find out the critical value of electric field frequency beyond which the system exhibits a transition back to the disordered state and this critical frequency is found as an increasing function of the electric field strength in the presence of an external magnetic field. The movement of the lanes is also observed in a direction perpendicular to that of the applied electric and magnetic field directions, which reveals the existence of the electric field drift in the system under study. We also use an oblique force field as the external driving force, both in the presence and absence of the external magnetic field. The application of this oblique force changes the orientation of the lane structures for different applied oblique angle values.

5 citations


Cited by
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TL;DR: In this paper, the effect of geometric aspect ratio on the stability of lane formation is systematically determined in both the presence and absence of an obstacle, and it is shown that an obstacle promotes the merging of lanes, and the system gradually transitions to a partially mixed phase with higher value of aspect ratio.
Abstract: Lane formation dynamics of driven two-dimensional pair-ion plasmas is investigated in under-damped cases where the effect of particle inertia cannot be neglected. Extensive Langevin dynamics simulations using an OpenMP parallel program are carried out to analyse the effect of obstacle and geometric aspect ratio on lane formation dynamics previously reported in Sarma et al. (Phys. Plasmas, vol. 27, 2020, 012106) and Baruah et al. (J. Plasma Phys., vol. 87, 2021, 905870202). Lanes are found to form when like particles move along or opposite to the applied field direction. Lane order parameter, cumulative order parameter and distribution of the order parameter have been implemented to detect phase transition. The effect of geometric aspect ratio on the stability of lanes is systematically determined in both the presence and absence of an obstacle. Here, a specular reflective boundary condition is implemented to mimic an obstacle. We demonstrate that an obstacle promotes the merging of lanes, and the system gradually transitions to a partially mixed phase with higher value of aspect ratio. The occurrence of lane mixing phenomena at the separation boundary of two oppositely flowing lanes at higher value of aspect ratio is observed. In the presence of an oscillatory electric field, the lane merging tendency is reduced to a large extent as compared to the system where a constant electric field is applied. Furthermore, in the presence of both space- and time-varying electric fields, an appearance of a void is observed on either side of the obstacle. The study finds that the presence of an external magnetic field promotes acceleration of the phase transition process towards the lane mixing phase; it also reveals the existence of electric field drift in the system. Our findings may prove to be useful in understanding the nature of lane dynamics in naturally occurring pair-ion plasma systems as well as their relevance to technological applications that exploit or mitigate self-organization.

2 citations

Journal ArticleDOI
TL;DR: Baruah et al. as mentioned in this paper investigated the influence of an external electric field on the behavior of a driven three-dimensional pair-ion plasmas (PIP) system and showed that the system undergoes a non-equilibrium phase transition from a disordered state to a lane formation state parallel to the field direction with increasing field strength.
Abstract: Lane formation dynamics of driven three-dimensional pair-ion plasmas (PIP) is investigated. Extensive Langevin dynamics simulation is performed to study the influence of an external electric field on the behaviour of the PIP system. In our model, one half of the particles are pushed into the field direction by an external force $\boldsymbol {F}_{A}$ while the other half are pulled into the opposite direction by an external force $\boldsymbol {F}_{B}$ . We show that if $\boldsymbol {F}_{A}$ and $\boldsymbol {F}_{B}$ are parallel, the system undergoes a non-equilibrium phase transition from a disordered state to a lane formation state parallel to the field direction with increasing field strength. The lanes are formed by the same kind of particles moving collectively with the field. The lane order parameter has been implemented to detect phase transition. Further, we show the lane formation in the presence of a time-varying external electric field. In particular, the effect of parallel forces are investigated. Unlike the previously reported two-dimensional case (Sarma, et al. , Phys. Plasmas , vol. 27, 2020, p. 012106; Baruah, et al. , J. Plasma Phys. , vol. 87, issue 2, 2021, p. 905870202), for the time-varying electric field case, spontaneous formation and the breaking of lanes are not observed for all values of applied frequencies; however, the orderness varies and spontaneous formation and breaking of lanes is observed for values close to a critical frequency $\omega _c$ . Further, some aspects of the lane formation dynamics of a PIP system are also studied in the presence of an external magnetic field, which reveals that the presence of an external magnetic field accelerates the lane formation process and introduces a drift of the lanes in a direction perpendicular to both electric and magnetic fields.

2 citations

Journal ArticleDOI
TL;DR: Baruah et al. as mentioned in this paper investigated the influence of an external electric field on the behavior of the driven three-dimensional pair-ion plasmas (PIP) and showed that the system undergoes a non-equilibrium phase transition from a disordered state to a lane formation state parallel to the field direction with increasing field strength.
Abstract: Lane formation dynamics of driven three-dimensional pair-ion plasmas (PIP) is investigated. Extensive Langevin dynamics simulation is performed to study the influence of an external electric field on the behaviour of the PIP system. In our model, one half of the particles are pushed into the field direction by an external force $\boldsymbol {F}_{A}$ while the other half are pulled into the opposite direction by an external force $\boldsymbol {F}_{B}$. We show that if $\boldsymbol {F}_{A}$ and $\boldsymbol {F}_{B}$ are parallel, the system undergoes a non-equilibrium phase transition from a disordered state to a lane formation state parallel to the field direction with increasing field strength. The lanes are formed by the same kind of particles moving collectively with the field. The lane order parameter has been implemented to detect phase transition. Further, we show the lane formation in the presence of a time-varying external electric field. In particular, the effect of parallel forces are investigated. Unlike the previously reported two-dimensional case (Sarma, et al., Phys. Plasmas, vol. 27, 2020, p. 012106; Baruah, et al., J. Plasma Phys., vol. 87, issue 2, 2021, p. 905870202), for the time-varying electric field case, spontaneous formation and the breaking of lanes are not observed for all values of applied frequencies; however, the orderness varies and spontaneous formation and breaking of lanes is observed for values close to a critical frequency $\omega _c$. Further, some aspects of the lane formation dynamics of a PIP system are also studied in the presence of an external magnetic field, which reveals that the presence of an external magnetic field accelerates the lane formation process and introduces a drift of the lanes in a direction perpendicular to both electric and magnetic fields.

1 citations

Journal ArticleDOI
TL;DR: In this article , the lane formation dynamics in the presence of non-parallel external forcing, and the effect of both constant and time varying forces are studied, and a spontaneous formation and breaking of lanes are observed when under the influence of time-varying forces.
Abstract: In Part 1 of the companion paper, we have investigated lane formation dynamics of driven three-dimensional (3-D) pair-ion plasmas (PIP) in the presence of parallel external forcing using extensive Langevin dynamics (LD) simulation. In continuation of the work, in this Part 2, we investigate lane formation dynamics in the presence of non-parallel external forcing, and the effect of both constant and time varying forces are studied. In our model, positively charged PIP particles are pushed into the field direction by an external force $\boldsymbol{F}_{A} = E_A\cos \omega _At$ while the negatively charged PIP particles are pulled by an external force $\boldsymbol{F}_{B} = E_B\cos \omega _Bt$ in a direction perpendicular to the external force $\boldsymbol{F}_{A}$. We show that in the case of non-parallel forces, the lanes are observed with an orientation (characterised by angle of inclination $\theta$) tilted in the direction of the force difference vector ($\boldsymbol{F}_{A} - \boldsymbol{F}_{B}$). The instantaneous lane order parameter, order parameter with gradient of angle of inclination ($\phi (\theta )$) and distribution function of $\Delta \theta$ have been implemented to characterise the phase transition. A spontaneous formation and breaking of lanes are observed when under the influence of time-varying forces. The effect is further investigated for three different situations: first, when $\omega _A eq 0$ and $\omega _B = 0$; second, when $\omega _A = \omega _B eq 0$; and third, for $\omega _A eq \omega _B eq 0$. Our study reveals that for the first case, a periodic oscillation of angle of inclination is observed. If oscillating forces of the same frequency are applied, the oscillation in angle of inclination disappears, and spontaneous formation and breaking of lanes is observed. However, in the presence of forces with different frequencies, flipping of lane inclination between the positive and negative domain of $\theta$ is observed. Further, some aspects of the lane formation dynamics of a PIP system is also studied in the presence of an external magnetic field where the lane formation dynamics is found to be accelerated.
Journal ArticleDOI
TL;DR: In this article , the lane formation dynamics in the presence of non-parallel external forcing, and the effect of both constant and time varying forces are studied, and spontaneous formation and breaking of lanes are observed when under the influence of time-varying forces.
Abstract: In Part 1 of the companion paper, we have investigated lane formation dynamics of driven three-dimensional (3-D) pair-ion plasmas (PIP) in the presence of parallel external forcing using extensive Langevin dynamics (LD) simulation. In continuation of the work, in this Part 2, we investigate lane formation dynamics in the presence of non-parallel external forcing, and the effect of both constant and time varying forces are studied. In our model, positively charged PIP particles are pushed into the field direction by an external force $\boldsymbol{F}_{A} = E_A\cos \omega _At$ while the negatively charged PIP particles are pulled by an external force $\boldsymbol{F}_{B} = E_B\cos \omega _Bt$ in a direction perpendicular to the external force $\boldsymbol{F}_{A}$ . We show that in the case of non-parallel forces, the lanes are observed with an orientation (characterised by angle of inclination $\theta$ ) tilted in the direction of the force difference vector ( $\boldsymbol{F}_{A} - \boldsymbol{F}_{B}$ ). The instantaneous lane order parameter, order parameter with gradient of angle of inclination ( $\phi (\theta )$ ) and distribution function of $\Delta \theta$ have been implemented to characterise the phase transition. A spontaneous formation and breaking of lanes are observed when under the influence of time-varying forces. The effect is further investigated for three different situations: first, when $\omega _A eq 0$ and $\omega _B = 0$ ; second, when $\omega _A = \omega _B eq 0$ ; and third, for $\omega _A eq \omega _B eq 0$ . Our study reveals that for the first case, a periodic oscillation of angle of inclination is observed. If oscillating forces of the same frequency are applied, the oscillation in angle of inclination disappears, and spontaneous formation and breaking of lanes is observed. However, in the presence of forces with different frequencies, flipping of lane inclination between the positive and negative domain of $\theta$ is observed. Further, some aspects of the lane formation dynamics of a PIP system is also studied in the presence of an external magnetic field where the lane formation dynamics is found to be accelerated.