arXiv subjects

Modhuchandra Laishram

Publications and source records attributed to Modhuchandra Laishram.

7 recordsLinked to original sources

arXiv2026

Canonical Vorticity Perspective on Magnetogenesis: Unifying Weibel, Biermann, and Beyond

We briefly review the current status of magnetogenesis, a cross-disciplinary field that bridges cosmology and plasma physics, studying the origin of magnetic fields in the universe. We formulate a canonical vorticity framework to investigate kinetic plasma physics-based magnetogenesis processes in a collisionless plasma. By considering canonical vorticity, a weighted sum of the fluid vorticity and the magnetic field as the canonical variable, this framework unifies several magnetogenesis processes, including the Biermann battery, the Weibel instability, and predicts several new pressure tensorial configurations as the fundamental source of self-generated magnetic field and vorticity in plasma. The framework is further extended to relativistic regime where an additional source of canonical vorticity, termed as kineclinicity effect, is identified. The theoretical predictions are systematically validated using particle-in-cell simulations, highlighting their implications for laboratory and astrophysical plasma environments.

physics.plasm-ph↗

arXiv2026

Kineclinic magnetogenesis in relativistic collisionless plasmas

The relativistic momentum equation of a collisionless plasma is reformulated to describe the time evolution of canonical vorticity. Compared to the non-relativistic counterpart, an additional source term for canonical vorticity is identified, which embodies the misalignment between the fluid momentum and fluid velocity gradients. This kineclinic term breaks the frozen-in condition of canonical vorticity, thereby enabling generation or dissipation of magnetic fields and vorticity. We verify the role of this effect through particle-in-cell simulations of a modified Beltrami flow. Kineclinicity should be finite for all relativistic plasma systems due to the general lack of a functional relationship between fluid momentum and fluid velocity.

physics.plasm-ph↗

arXiv2020

Driven dust vortex characteristics in plasma with external transverse and weak magnetic field

The two-dimensional hydrodynamic model for bounded dust flow dynamics in plasma is extended for analysis of driven vortex characteristics in presence of external transverse and weak magnetic field (${\bf B}$) in a planner setup and parametric regimes motivated by recent magnetized dusty plasma (MDP) experiments. This analysis has shown that shear in the ${\bf B}$ can produce a shear internal field (${\bf E_a}$) in between electrons and ions due to the ${\bf E}\times {\bf B}$ and ${\nabla {\bf B}}\times {\bf B}$-drifts that cause rotation of dust cloud levitated in the plasma. The flow solution demonstrates that neutral pressure decides the dominance between the ions-drag and the ${\bf E_a}$-force. The shear ions-drag generates an anti-clockwise circular vortical structure, whereas the shear ${\bf E_a}$-force is very localized and gives rise to a clockwise $D$-shaped elliptical structure which turns into a meridional structure with decreasing ${\bf B}$. Effect of system parameters including the strength of ${\bf B}$ by varying its magnitude and shear mode numbers and the sheath field are analyzed within the weak MDP regime, showing noticeable changes in the flow structure and its momentum. In the parametric regime of high pressure and lower ${\bf B}$, the ${\bf E_a}$-force becomes comparable or dominant over the ion drag and peculiar counter-rotating vortex pairs are developed in the domain. Further, when the ${\bf B}$ is flipped by $180^0$-degree, both the drivers act together and give rise to a single strong meridional structure, showing the importance of ${\bf B}$-direction in MDP systems. It further discussed similar elliptical/meridional structures reported in several MDP experiments and relevant natural driven-dissipative flow systems.

physics.plasm-ph↗

arXiv2019

Extended hybrid kinetic-magnetohydrodynamic model for ignited burning plasmas

A brief review of the existing kinetic-magnetohydrodynamic(MHD) hybrid models for the alpha particle physics in burning plasma demonstrates that the pressure-coupling scheme is equivalent to the current-coupling scheme only in a specific dynamic regime where the alpha particle density is much lower than the background ion and electron. A more comprehensive kinetic-multifluid model is proposed for a proper account of the dynamical regime of the burning plasma where both the energetic alpha and the helium ash particles are present. The Kinetic-multifluid model is further simplified into an extended hybrid kinetic-MHD model in the MHD limit. This reduction process demonstrates that the existing pressure-coupling scheme is more extensive than the current-coupling scheme and sufficient for the wide range of dynamical regimes. This analysis further shows a significant change in the model equations mainly the generalized Ohm's law due to the contributions of a significant amount of alpha particles in the system. These models can be used for studies of the impact of the alpha particles present in ignited burning plasma and space plasma.

physics.plasm-ph↗

arXiv2018

Sequential steady state co-rotating dust vortices in sheared streaming plasma

The 2D hydrodynamic model for a dust cloud confined in an axisymmetric toroidal system volumetrically driven by an unbounded streaming plasma is further extended systematically for different aspect-ratio of the bounded dust domain and a wide range of the kinematic viscosity. This work has demonstrated the interplay between inertial and diffusive transport processes for the structural changes of steady dust flow from symmetric into asymmetric nature in higher Reynolds number (Re) regimes where flow streamlines turn more circular and the structural bifurcation takes place through a threshold parameter. In agreement with many experimental observations, the steady vortex structure in highly nonlinear (i.e., high Re) regime is characterized by the critical transition into a new self-similar multiple co-rotating vortices, along with circular core region of single characteristics size and surrounded by strongly sheared layers filled with weak vortices near the boundaries. It is further revealed that the core region persists for a wide range of system parameters in the nonlinear regime and its characteristic size is mainly determined by the smallest distance between the confining boundaries. The threshold parameter, the vortex size, the strength, and the number of the self-similar co-rotating vortices mainly depend on the aspect-ratio of the bounded dust domain. These nonlinear solutions provide insight into the phenomena of the structural transition and coexistence of self-similar steady co-rotating vortices in dusty plasma experiments as well as many relevant complex driven-dissipative natural flow systems.

physics.plasm-ph↗

arXiv2018

A dusty plasma model for vortex structure in Jupiter atmosphere

Structural changes of self-organized vortices in Jupiter atmospheres such as Great Red Spot (GRS) and White Ovals are demonstrated using an electrostatically bounded charged dust cloud in an unbounded streaming plasma as the prototype for various driven-dissipative complex flow systems in nature. Using a 2D hydrodynamic model, the steady state flow solutions are obtained for the volumetrically driven dust cloud in a bounded domain of aspect-ratio of 1.5 relevant to the current size of GRS and a driving sheared ion flow similar to the part of zonal jets streaming through the GRS. These nonlinear solutions reveal many similar characteristic features between the steadily driven dust circulation in laboratory experiments and the vortices in Jupiter atmosphere. Starting from the continuous structural changes, the persistence of high-speed collar ring around the quiescent interior of uniform vorticity of GRS and White Ovals are interpreted as a consequence of changes in internal properties related to kinematic viscosity rather than the driving fields. This the analysis also sheds light on the roles of driving field, boundaries, and dynamical parameters regime in determining the characteristic size, the strength, the circulating direction, and the drift of the vortices in Jupiter atmosphere and other relevant driven-dissipative flow systems in nature.

physics.plasm-ph↗

arXiv2018

Structural transition of vortices to nonlinear regimes in a dusty plasma

A 2D hydrodynamical model is developed and analyzed for the steady state of a driven-dissipative dust clouds confined in an azimuthally symmetric toroidal system which is in dynamic equilibrium with background unbounded streaming plasma. Its numerical solution not only confirms the analytical structure of the driven dust vortex flow in linear limit as reported in previous analysis, but also shows how the dust vortices are strongly affected by the nonlinear convection of the flow itself. Effects of various system parameters including external driving field and Reynolds number (Re) are investigated within the linear to nonlinear transition regime $0.001\le {\rm Re} < 50$. In agreement with various relevant experimental observations, the flow structure which is symmetric around center in the linear regime begins to turn asymmetric in the nonlinear regime. The equilibrium structure of dust flow is found to be influenced mainly by the dissipation scales due to kinematic viscosity, ion drag, and neutral collision in the nonlinear regime, whereas in the linear regime, it is mainly controlled by the external driving field and the confining boundaries.

physics.plasm-ph↗