arXiv subjects

Kishor Kumbhar

Publications and source records attributed to Kishor Kumbhar.

3 recordsLinked to original sources

arXiv2026

Evidence of energy conversion in weakly collisional plasma during an interplanetary coronal mass ejection

Intervals of enhanced turbulent fluctuations are typically less frequent within the magnetic cloud region of an interplanetary coronal mass ejection (ICME). We investigate two such intervals inside an ICME observed by the \textit{Wind} spacecraft on 8--9 June 2000 and characterize their associated wave populations. We focus on spectral analysis and plasma instability analysis, using ion-scale normalized magnetic helicity and polarization properties with respect to the background magnetic field $B_0$. In the first interval, the ion-scale normalized magnetic helicity shows a left-handed circularly polarized signature. In the second interval, the left-handed signature persists and an additional high-frequency right-handed population appears. The propagation is approximately parallel to $B_0$. The left-handed fluctuations are compatible with Alfvén ion-cyclotron (AIC) waves, while the right-handed fluctuations are consistent with fast magnetosonic/whistler (FM/W) waves. The ICME plasma accesses resonance conditions that support multiple ion-scale wave modes. Evolving anisotropies in the plasma and the approach to marginal stability allow the coexistence of AIC-like and fast-magnetosonic/whistler-like fluctuations, with enhanced electron heating favoring the growth of the FM/W contribution and strengthening the density--magnetic-field magnitude correlation.

astro-ph.SR↗

arXiv2025

Magnetic Moment-Field Interactions, A Universal Mechanism for Particle Energization

Magnetic reconnection is a pivotal mechanisms in the energization and heating of cosmic plasmas, yet the exact process of energy transfer during these events remain elusive. Traditional models, which focus on acoustic and magnetohydrodynamic waves and micro/nano-flares, fall short of explaining the extreme heating of the solar corona and the origins of the supersonic solar wind. In this study, we provide compelling observational evidence from Wind spacecraft data supporting the Raghav effect, a mechanism where interactions between the magnetic moments of charged particles and dynamic magnetic fields result in abrupt kinetic energy changes. Our analysis demonstrates that the observed proton plasma heating is consistent with theoretical predictions, establishing the Raghav effect as a universal mechanism for particle energization. This discovery offers a unified framework for understanding energy dynamics across a wide range of astrophysical magnetised plasma environments.

astro-ph.SR↗

arXiv2021

The role of extreme geomagnetic storms in the Forbush decrease profile

The Forbush decrease (FD) and Geomagnetic storm (GS) are the two distinct space weather events having common causing agents like interplanetary coronal mass ejection (ICME) or corotating interacting region (CIR). Generally, an ICME causes high amplitude FDs and extreme GSs. However, the interlinks between extreme GS and strong FDs are poorly studied. Here, we demonstrate five ICME induced extreme storms and their effects on respective FD profiles. We observed the sudden storm commencement of the GS coincides with the FD onset. Interestingly, we also noted a gradual increase in neutron counts during the main and recovery phases of GS. The maximum enhancement in neutron counts coincides with the minimum value of the Sym-H index. The enhancement is visible primarily in all the neutron monitors but significantly pronounced in high-energy neutrons compared to low-energy neutrons. The weakening of Earth's magnetic shield due to ICME-Magnetosphere interaction allows more cosmic rays to reach the ground. Thus, we conclude that the geomagnetic storm conditions highly influence the FD profile along with the external causing agent. Therefore, it is essential to include the effect of geomagnetic field variation in the models that are used to reproduce the FD profile.

physics.space-ph↗