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Pedestal modelling is crucial to predict the performance of future fusion devices. Current modelling efforts suffer either from a lack of kinetic physics, or an excess of computational complexity. To ameliorate these problems, we take a…

Plasma Physics · Physics 2018-06-06 Ian Abel , Axel Hallenbert

In many astrophysical environments the plasma is only partially ionized, and therefore the interaction of charged and neutral particles may alter both the triggering of reconnection and its subsequent dynamical evolution. We derive the…

Solar and Stellar Astrophysics · Physics 2020-11-11 Fulvia Pucci , K. Alkendra P. Singh , Anna Tenerani , Marco Velli

By analyzing large quantities of discharges in the unfavorable ion $ \vec B\times \nabla B $ drift direction, the I-mode operation has been confirmed in EAST tokamak. During the L-mode to I-mode transition, the energy confinement has a…

The electromagnetic theory of the strongly driven ion-temperature-gradient (ITG) instability in magnetically confined toroidal plasmas is developed. Stabilizing and destabilizing effects are identified, and a critical $\beta_{e}$ (the ratio…

Plasma Physics · Physics 2015-02-23 A. Zocco , P. Helander , J. W. Connor

Avoidance of the harmful effects of runaway electrons (REs) in plasma-terminating disruptions is pivotal in the design of safety systems for magnetic fusion devices. Here, we describe a computationally efficient numerical tool, that allows…

Plasma Physics · Physics 2021-08-11 M. Hoppe , O. Embreus , T. Fülöp

The parametric instability of upper hybrid wave decay into back scattered upper hybrid wave and lower hybrid wave is considered for conditions of inhomogeneous plasma of spherical tokamaks. The possibility of absolute instability is…

Plasma Physics · Physics 2007-05-23 Evgeniy Gusakov , Alexander Surkov

The physical processes taking place at the edge region are crucial for the operation of tokamaks as they govern the interaction of hot plasma with the vessel walls. Numerical modeling of the edge with state-of-the-art codes attempts to…

Plasma Physics · Physics 2020-08-26 I. Keramidas Charidakos , J. R. Myra , S. Ku , R. M. Churchill , R. Hager , C. S. Chang , S. Parker

Field-line localized ballooning modes have been observed at the edge of high confinement mode plasmas in ASDEX Upgrade with rotating 3D perturbations induced by an externally applied n = 2 error field and during a moderate level of edge…

Analytic solutions of the magnetohydrodynamic equilibrium equations for a cylindrically symmetric magnetically confined plasma with reversed magnetic shear, s < 0, and sheared flow are constructed by prescribing the safety factor-, poloidal…

Plasma Physics · Physics 2007-05-23 G. Poulipoulis , G. N. Throumoulopoulos , H. Tasso

All current estimations of the energy released by type I ELMs indicate that, in order to ensure an adequate lifetime of the divertor targets on ITER, a mechanism is required to decrease the amount of energy released by an ELM, or to…

Conditions similar to those at the end of the divertor leg in a tokamak were replicated in the linear plasma machine Magnum-PSI. The neutral pressure in the target chamber is then increased to cause the target to transition from an attached…

There is a well established theory of Ballooning modes in a toroidal plasma. The cornerstone of this is a local eigenvalue lambda on each magnetic surface - which also depends on the ballooning phase angle k. In stationary plasmas lambda(k)…

Plasma Physics · Physics 2012-10-09 J. B. Taylor

We use the non-linear reduced-MHD code JOREK to study ELMs in the geometry of the ASDEX Upgrade tokamak. Toroidal mode numbers, poloidal filament sizes, and radial propagation speeds of filaments into the scrape-off layer are in good…

The mathematical description of laboratory fusion plasmas produced in Tokamaks is still challenging. Complete models for electrons and ions, as Vlasov-Maxwell systems, are computationally too expensive because they take into account all…

Analysis of PDEs · Mathematics 2012-04-23 Frédérique Charles , Bruno Després , Benoît Perthame , Remi Sentis

In the paradigm of magnetic acceleration of relativistic outflows, a crucial point is identifying a viable mechanism to convert the Poynting flux into the kinetic energy of the plasma, and eventually into the observed radiation. Since the…

High Energy Astrophysical Phenomena · Physics 2018-08-29 Emanuele Sobacchi , Yuri E. Lyubarsky

The influence of collisions on the growth rate of trapped-electron modes (TEMs) in core plasmas is assessed through both analytical linear gyrokinetics and linear gyrokinetic simulations. Both methods are applied to the magnetic geometry of…

Plasma Physics · Physics 2024-05-27 M. C. L. Morren , J. H. E. Proll , J. van Dijk , M. J. Pueschel

Locked modes are precursors to major disruptions. During locked modes, the temperature decreases in the plasma edge region. This causes the current to contract. A model is given to analyze the MHD stability of contracted current equilibria.…

Plasma Physics · Physics 2023-04-18 H. R. Strauss

Runaway electron loads onto material structures are a major concern for future large tokamaks due to the efficient avalanching at high plasma currents. Here, we perform predictive studies using the JOREK code for a plausible plasma…

The key basis for tokamak plasma disruption modeling is to understand how currents flow to the plasma facing surfaces during plasma disruption events. In ITER tokamak, the occurrence of a limited number of major disruptions will…

Plasma Physics · Physics 2022-01-26 Cǎlin V. Atanasiu , Leonid E. Zakharov , Karl Lackner , Matthias Hoelzl

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…