Results 41 to 50 of about 196 (131)

Axisymmetric global Alfvén eigenmodes in the TCV tokamak

Nuclear Fusion
Global Alfvén eigenmodes (GAEs) with toroidal mode number n = 0 (i.e. axisymmetric) have been observed in the toroidicity-induced, ellipticity-induced, and above non-circularity-induced frequency ranges in the TCV tokamak.
M. Dreval, S.E. Sharapov, H.J.C. Oliver, M. Fitzgerald, A.N. Karpushov, A. Jansen van Vuuren, J. Poley, M. Podesta, F. Porcelli, the TCV Team, the EUROfusion Tokamak Exploitation Team   +10 more
doaj   +1 more source

Topographic Drag at the Core‐Mantle Interface

Journal of Geophysical Research: Solid Earth, Volume 130, Issue 4, April 2025.
Abstract The length of day variations with periods from five to one hundred years are mainly due to core‐mantle interactions. Assuming a differential velocity between the core and the mantle, we investigate the pressure coupling on a core‐mantle boundary (CMB) interface with topography. Including rotation, buoyancy, and magnetic effects in local models
R. Monville, D. Cébron, D. Jault
wiley   +1 more source

Exact Nonlinear Decomposition of Ideal-MHD Waves Using Eigenenergies

The Astrophysical Journal
In this paper, we introduce a new method for exact decomposition of propagating, nonlinear magnetohydrodynamic (MHD) disturbances into their component eigenenergies associated with the familiar slow, Alfvén, and fast wave eigenmodes, and the entropy and ...
Axel Raboonik, Lucas A. Tarr, David I. Pontin   +2 more
doaj   +1 more source

Interplay of Magnetic Reconnection and Current Sheet Kink Instability in the Earth's Magnetotail

Geophysical Research Letters, Volume 52, Issue 2, 28 January 2025.
Abstract Magnetic reconnection and current sheet kink instability often develop concurrently in current sheets, yet their dynamic interplay remains unclear. We investigate their interaction in the magnetotail of a 3D global magnetospheric hybrid‐Vlasov simulation. We identify the instability growth and saturation phase and estimate the evolution of the
G. Cozzani, M. Alho, I. Zaitsev, H. Zhou, S. Hoilijoki, L. Turc, M. Grandin, K. Horaites, M. Battarbee, Y. Pfau‐Kempf, U. Ganse, K. Papadakis, M. Palmroth   +12 more
wiley   +1 more source

Modeling of frequency-sweeping Alfvén modes in the TJ-II stellarator

Nuclear Fusion
Alfvénic activity has been observed in the TJ-II stellarator which resembles the frequency sweeping demonstrated by Alfvén cascade modes in tokamaks. A numerical validation study was conducted using a reduced magnetohydrodynamic (MHD) model to show that ...
A.G. Ghiozzi, M.J. Mantsinen, P. Pastells, D.A. Spong, A.V. Melnikov, L.G. Eliseev, S.E. Sharapov   +6 more
doaj   +1 more source

Ion‐Mediated Tearing and Kink Instabilities in the Earth's Magnetosphere: Hybrid‐Vlasov Simulations

Journal of Geophysical Research: Space Physics, Volume 130, Issue 1, January 2025.
Abstract We explore the three‐dimensional structure of ion‐kinetic instabilities in a thin current layer using a hybrid‐Vlasov simulation of the Earth's magnetosphere. The simulation shows the simultaneous growth of tearing and kinking instabilities, which develop in the Sun‐Earth and dawn‐dusk directions, respectively, within the magnetotail current ...
I. Zaitsev, G. Cozzani, M. Alho, K. Horaites, H. Zhou, A. Kit, Y. Pfau‐Kempf, S. Hoilijoki, U. Ganse, M. Battarbee, K. Papadakis, J. Suni, M. Dubart, F. Tesema‐Kebede, A. Workayehu, V. Tarvus, L. Kotipalo, V. Koikkalainen, L. Turc, M. Palmroth   +19 more
wiley   +1 more source

Could a Low‐Frequency Perturbation in the Earth's Magnetotail Be Generated by the Lunar Wake?

Geophysical Research Letters, Volume 51, Issue 22, 28 November 2024.
Abstract Both ground based magnetometers and ionospheric radars at Earth have frequently detected Ultra Low Frequency (ULF) fluctuations at discrete frequencies extending below one mHz‐range. Many dayside solar wind drivers have been convincingly demonstrated as driver mechanisms.
K. Nykyri, S. Di Matteo, M. O. Archer, X. Ma, M. D. Hartinger, M. Sarantos, E. Zesta, W. R. Paterson   +7 more
wiley   +1 more source

Radiative damping of toroidal Alfvén eigenmode in low-shear plasmas

Fundamental Plasma Physics
Instabilities of Alfvén eigenmodes (AEs) are of significant concern because they can enhance the cross-field transport of fusion-born alpha particles beyond the neoclassical level in magnetic fusion plasmas. The threshold value of alpha-particle pressure
B.N. Breizman, S.E. Sharapov
doaj   +1 more source

Observation of bi-directional global Alfvén eigenmodes in the MAST-U tokamak

Nuclear Fusion
The first observations and classification of deuterium beam-driven sub-cyclotron frequency range Alfvén eigenmodes (AEs) are presented for the MAST-Upgrade tokamak. Sets of observed eigenmodes are separated in frequency by approximately 200 kHz.
M.B. Dreval, H.J.C. Oliver, S.E. Sharapov, J.F. Rivero-Rodriguez, M. Fitzgerald, C. Michael, R. Ochoukov, L. Velarde, M. Cecconello, D. Ryan, the MAST-U Team   +10 more
doaj   +1 more source

Characteristics of the Alfvénic activity during the current quench in ASDEX Upgrade

Nuclear Fusion
ASDEX Upgrade has developed multiple massive gas injection (MGI) scenarios to investigate runaway electron (RE) dynamics. During the current quench of the MGI induced disruptions, Alfvénic activity is observed in the 300–800 kHz range. With the help of a
P. Heinrich, G. Papp, Ph. Lauber, G. Pautasso, M. Dunne, M. Maraschek, V. Igochine, O. Linder, the ASDEX Upgrade Team, the EUROfusion Tokamak Exploitation Team   +9 more
doaj   +1 more source