A. Ishizawa

Investigation of magnetic field ripple effects on charged particles transport in scrape-off layer of Heliotron J

Furui Cai, S. Kado, G. Kawamura, Yuhe Feng et autres

Abstract The impact of helical magnetic ripples on the transport of plasma and carbon impurities in the scrape-off layer (SOL) of a Heliotron J device was investigated using the EMC3-EIRENE code. Comparisons with a simplified one-dimensional fluid model revealed that the transport …

jp, de, us (code pays fourni par la source)

Assessment of divertor structures arising from invariant features in Hamiltonian system for three-dimensional magnetic field in Heliotron J

Furui Cai, S. Kado, G. Kawamura, Yuhe Feng et autres

Abstract The divertor structures of Heliotron J were investigated by analyzing the three-dimensional magnetic field and plasma transport simulations. The magnetic field of Heliotron J typically exhibits a characteristic resonant structure, where the stable and unstable manifolds emanating from specific X-points determine …

jp, de, us (code pays fourni par la source)

Parameter dependence of pressure-gradient driven plasmoid formation and its ejection from host magnetic island

J. Liu, Masahiko Sato, A. Ishizawa

Abstract The dynamics of a pressure-gradient driven plasmoid (p-plasmoid) are investigated using numerical simulations based on a two-fluid model of magnetized plasmas, including ion and electron diamagnetic effects. The p-plasmoid is devoid of a pressure gradient confined by locally concentric magnetic flux …

jp (code pays fourni par la source)

Influence of magnetic shear on kinetic ballooning modes and electromagnetic stellarator turbulence

Paul Mulholland, K. Aleynikova, M. J. Pueschel, Josefine Proll et autres

Abstract The influence of magnetic shear on kinetic ballooning modes (KBMs) and electromagnetic turbulence is reported in the Wendelstein 7-X (W7-X) and Heliotron-J (H-J) stellarators. Gyrokinetic simulations at finite normalized plasma pressure β reveal that sub-threshold KBMs (stKBMs) are present in all …

nl, de, jp (code pays fourni par la source)

Application of non-integer- n RMP coil current waveform for ELM control in JA DEMO

Shota Sugiyama, N. Aiba, Yasuhiro Suzuki, Go Matsunaga et autres

Abstract We have studied the resonant magnetic perturbation (RMP) coil concept for edge localized mode (ELM) suppression in JA DEMO, a design concept of a steady-state tokamak demonstration reactor, based on the vacuum magnetic model. We investigate the RMP coil layout and …

jp (code pays fourni par la source)

Characterisation of turbulence suppression by fast-ion-Alfvénic instability

A. Ishizawa, A. Di Siena, T.S. Hahm

Abstract Turbulence causes anomalous transport of plasma and thus limits achieving high temperature and density of magnetically confined fusion plasmas. Recently, fast-ion-driven Alfvénic instabilities were found to influence plasma thermal confinement by regulating turbulence. However, both favourable and unfavourable effects coming from …

jp, de, kr (code pays fourni par la source)

Is Turbulence able to Generate Magnetic Islands in Tokamaks? Gyrokinetic Simulations of Turbulence-Driven Magnetic Islands in Toroidal Geometry

Fabien Widmer, A. Mishchenko, A. Ishizawa, T. Hayward-Schneider et autres

We report a universal mechanism for turbulence-driven magnetic islands in fusion plasmas. Using gyrokinetic simulations of a linearly stable tearing mode in a large-aspect-ratio toroidal geometry under collisionless conditions, we demonstrate that micro-instabilities generate an $\boldsymbol{E}\times\boldsymbol{B}$ flow that drives magnetic field line …

Understanding turbulence suppression in JET D–T plasma with highly energetic fast ions via global gyrokinetic GENE simulations

A. Di Siena, J. García, G. Merlo, A. Bañón Navarro et autres

Abstract This study focuses on understanding how turbulence is suppressed in particularly heated JET plasma discharges showing enhanced confinement, namely 99896 , which uses a nearly 50–50 deuterium–tritium mixture, showing signs of enhanced plasma confinement. The discharge was heated primarily using ion-cyclotron-resonance …

de, fr, jp, us (code pays fourni par la source)

Characteristics of global dispersion and mode distribution modeled for JT-60U like strongly reversed magnetic shear plasmas exhibiting L-modes with strong profile constraints

Rui Zhao, Kenji Imadera, Jianfu Liu, Wei Wang et autres

Abstract The eigen-mode structure and distribution associated with the global dispersion are studied based on linear gyro-kinetic simulations in a global toroidal geometry using parameters and profiles modeled for JT-60U like discharges with a strongly reversed magnetic shear configuration, which exhibit L-mode …

jp, gb, cn (code pays fourni par la source)

High-sensitivity measurement of Zeeman effect using hydrogen Paschen-α emission line in fusion-divertor-relevant plasma

Minato Murakumo, T. Shikama, S. Kado, A. Iwata et autres

In magnetically confined fusion reactors, the Zeeman effect can sometimes be utilized in spatially resolved spectroscopy to localize the observed line emission. To apply this method to divertor plasma spectroscopy, the relative magnitude of the Zeeman splitting to linewidth for hydrogen atomic …

jp, us (code pays fourni par la source)

Rotating flux-tube model for local gyrokinetic simulations with background flow and magnetic shears

S. Maeyama, M. Nakata, M. Nunami, Yuuichi Asahi et autres

We have developed a new computational method called the rotating flux-tube model that treats background shear flows in local gyrokinetic simulations. The method is based on extended magnetohydrodynamic ballooning mode theory. A coordinate transformation moves the flux-tube simulation domain along the sheared …

jp, fr (code pays fourni par la source)

Linear and nonlinear dynamics of self-consistent collisionless tearing modes in toroidal gyrokinetic simulations

Fabien Widmer, E. Poli, A. Mishchenko, A. Ishizawa et autres

We investigate tearing modes (TM) driven by current density gradient in collisionless tokamak plasmas by using the electromagnetic gyrokinetic simulation code ORB5. We elucidate the TM width by simulations for flat profiles, as the absence of background diamagnetic flows implies a small …

jp, de (code pays fourni par la source)