arXiv subjects

K. Nykyri

Publications and source records attributed to K. Nykyri.

3 recordsLinked to original sources

arXiv2026

Stern--Gerlach Spin Sorting and Dynamical Feedback in Relativistic Pair-Plasma Reconnection

We derive a Stern--Gerlach control parameter, $Ξ$, comparing spin-driven cross-sheet displacement with the relativistic Larmor radius. It places heliospheric plasmas and most astrophysical jets in the negligible regime, some stellar-mass black-hole coronae in a transitional regime, and magnetar sheets in a strong, near-QED regime. Relativistic pair-plasma simulations at fixed $γ_{\rm tr}=2$ show that increasing $Ξ$ produces, within the coupled SG+$\mathbf J_M$ model, magnetic-moment sorting and magnetization-current feedback that enhance the normalized flux-growth rate through an additional spin-kinetic pathway beyond classical pressure- and geometry-controlled pair-plasma reconnection.

physics.plasm-ph↗

arXiv2026

Relativistic Scaling and Magnetization-Current Feedback in Stern Gerlach-Modified Pair-Plasma Reconnection: SpinPIC2D Validation and Nonlinear Regimes

We investigate the relativistic scaling and electromagnetic feedback of Stern--Gerlach (SG) force driven spin transport in pair-plasma reconnection with SpinPIC2D. The model advances relativistic proper momentum and magnetic BMT spin precession, applies the SG force, deposits spin magnetization, and includes $\mathbf J_M=\nabla\times\mathbf M$ in Ampere's law. In a weak-seed scan at fixed $γ_{\rm tr}=2$, the normalized global magnetic flux-growth remains near the classical control-run for $Ξ\le0.1$, is $0.016$ at $Ξ=0.4$, and reaches approximately $0.12$ and $0.25$ at $Ξ=0.7$ and 1, respectively over $3\le t/τ_{\rm sp}\le7$. Because $\partial/\partial y=0$ in the 2.5-D geometry, the direct $y$-directed SG term vanishes and the enhancement is indirect: sheet-normal SG sorting restructures branch-resolved electron and positron velocity distributions which results in changes in pressure moments and generates a layered magnetization current. Along a fixed-$χ_{\rm sim}$ family, increasing $γ_{\rm tr}$ reduces $Ξ$ and suppresses branch sorting, whereas the matched-control flux-growth enhancement remains positive for $γ_{\rm tr}=2,3,5$. Retuning $χ_{\rm sim}$ to hold $Ξ=1$ does not preserve nonlinear similarity: both the coupling and $J_{M,y}$ increase with $γ_{\rm tr}$, and the $γ_{\rm tr}=5$ case develops a multi-X-line state. Thus $Ξ$ orders the onset of SG-modified reconnection, while the nonlinear response also depends on the absolute spin coupling and magnetization-current amplitude.

physics.plasm-ph↗

arXiv2023

Unveiling plasma energization and energy transport in the Earth Magnetospheric System: the need for future coordinated multiscale observations

Energetic plasma is everywhere in the Universe. The terrestrial Magnetospheric System is a key case where direct measures of plasma energization and energy transport can be made in situ at high resolution. Despite the large amount of available observations, we still do not fully understand how plasma energization and energy transport work. Key physical processes driving much plasma energization and energy transport occur where plasma on fluid scales couple to the smaller ion kinetic scales. These scales (1 RE) are strongly related to the larger mesoscales (several RE) at which large-scale plasma energization and energy transport structures form. All these scales and processes need to be resolved experimentally, however existing multi-point in situ observations do not have a sufficient number of measurement points. New multiscale observations simultaneously covering scales from mesoscales to ion kinetic scales are needed. The implementation of these observations requires a strong international collaboration in the coming years between the major space agencies. The Plasma Observatory is a mission concept tailored to resolve scale coupling in plasma energization and energy transport at fluid and ion scales. It targets the two ESA-led Medium Mission themes Magnetospheric Systems and Plasma Cross-scale Coupling of the ESA Voyage 2050 report and is currently under evaluation as a candidate for the ESA M7 mission. MagCon (Magnetospheric Constellation) is a mission concept being studied by NASA aiming at studying the flow of mass, momentum, and energy through the Earth magnetosphere at mesoscales. Coordination between Plasma Observatory and MagCon missions would allow us for the first time to simultaneously cover from mesoscales to ion kinetic scales leading to a paradigm shift in the understanding of the Earth Magnetospheric System.

physics.space-ph↗