Impact of screening of resonant magnetic perturbations in three dimensional edge plasma transport simulations for DIII-D

Frerichs, H.; Reiter, D.; Schmitz, O.; Cahyna, P.; Evans, T.E.; Feng, Y.; Nardon, E.

doi:10.1063/1.4714616

Cited by 29 publications

(26 citation statements)

References 31 publications

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“…However, the parallel heat flux into the perturbed structures is much smaller than expected intuitively and also from 3D plasma fluid and kinetic neutral transport modeling even when screening out to the very edge is included. 35…”

Section: Heat and Particle Flux Measurements In H-modementioning

confidence: 99%

Heat flux modeling using ion drift effects in DIII-D H-mode plasmas with resonant magnetic perturbations

et al. 2014

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The heat flux patterns measured in low-collisionality DIII-D H-mode plasmas strongly deviate from simultaneously measured CII emission patterns, used as indicator of particle flux, during applied resonant magnetic perturbations. While the CII emission clearly shows typical striations, which are similar to magnetic footprint patterns obtained from vacuum field line tracing, the heat flux is usually dominated by one large peak at the strike point position. The vacuum approximation, which only considers applied magnetic fields and neglects plasma response and plasma effects, cannot explain the shape of the observed heat flux pattern. One possible explanation is the effect of particle drifts. This is included in the field line equations and the results are discussed with reference to the measurement. Electrons and ions show different drift motions at thermal energy levels in a guiding center approximation. While electrons hardly deviate from the field lines, ions can drift several centimetres away from field line flux surfaces. A model is presented in which an ion heat flux, based on the ion drift motion from various kinetic energies as they contribute to a thermal Maxwellian distribution, is calculated. The simulated heat flux is directly compared to measurements with a varying edge safety factor q 95. This analysis provides evidence for the dominate effect of high-energy ions in carrying heat from the plasma inside the separatrix to the target. High-energy ions are deposited close to the unperturbed strike line, while low-energy ions can travel into the striated magnetic topology. V

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Section: Heat and Particle Flux Measurements In H-modementioning

confidence: 99%

Heat flux modeling using ion drift effects in DIII-D H-mode plasmas with resonant magnetic perturbations

et al. 2014

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“…Models of plasma response based on a simplified assumption of screening currents on resonant surfaces [39] or on a linear MHD model [40] predict significant shortening of the lobes when the RMP is screened by the plasma response. Shortening is observed in the magnetic field topology [38][39][40] and through the reduction of fluxes [41,42] and generally increases with the increase of the width of the plasma region where the RMP is screened [39]. The shortening of lobes currently represent the most convenient way to quantify experimentally the screening of RMPs.…”

Section: Stochasticity At the Edgementioning

confidence: 99%

Non-linear magnetohydrodynamic modeling of plasma response to resonant magnetic perturbations

et al. 2013

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The interaction of static Resonant Magnetic Perturbations (RMPs) with the plasma flows is modeled in toroidal geometry, using the non-linear resistive MHD code JOREK, which includes the X-point and the Scrape-Off-Layer. Two-fluid diamagnetic effects, the neoclassical poloidal friction and a source of toroidal rotation are introduced in the model to describe realistic plasma flows. RMP penetration is studied taking self-consistently into account the effects of these flows and the radial electric field evolution. JET-like, MAST and ITER parameters are used in modeling. For JET-like parameters, three regimes of plasma response are found depending on the plasma resistivity and the diamagnetic rotation: at high resistivity and slow rotation, the islands generated by the RMPs at the edge resonant surfaces rotate in the ion diamagnetic direction and their size oscillates. At faster rotation, the generated islands are static and are more screened by the plasma. An intermediate regime with static islands which slightly oscillate is found at lower resistivity. In ITER simulations, the RMPs generate static islands, which forms an ergodic layer at the very edge (ψ ≥ 0.96) characterized by lobe structures near the X-point and results in a small strike point splitting on the divertor targets. In MAST DND geometry, lobes are also found near the X-point and the 3D-deformation of the density and temperature profiles is observed.

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“…However, the addition of a typical perturbing robust barrier to the system, as the ones observed in the experiments described by Refs. [40][41][42] , produces a Hamiltonian on the form of (7) for wave-particle interactions:…”

Section: Improving Particle Accelerationmentioning

confidence: 99%

Improving particle beam acceleration in plasmas

Sousa

Caldas

2018

Physics of Plasmas

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The dynamics of wave-particle interactions in magnetized plasmas restricts the wave amplitude to moderate values for particle beam acceleration from rest energy. We analyze how a perturbing invariant robust barrier modifies the phase space of the system and enlarges the wave amplitude interval for particle acceleration.For low values of the wave amplitude, the acceleration becomes effective for particles with initial energy close to the rest energy. For higher values of the wave amplitude, the robust barrier controls chaos in the system and restores the acceleration process. We also determine the best position for the perturbing barrier in phase space in order to increase the final energy of the particles.

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Impact of screening of resonant magnetic perturbations in three dimensional edge plasma transport simulations for DIII-D

Cited by 29 publications

References 31 publications

Heat flux modeling using ion drift effects in DIII-D H-mode plasmas with resonant magnetic perturbations

Heat flux modeling using ion drift effects in DIII-D H-mode plasmas with resonant magnetic perturbations

Non-linear magnetohydrodynamic modeling of plasma response to resonant magnetic perturbations

Improving particle beam acceleration in plasmas

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