Radio frequency heating induced edge plasma convection: self-consistent simulations and experiments on ASDEX Upgrade

Zhang, W.; Tierens, W.; Noterdaeme, Jean-Marie; Bobkov, V.; Aguiam, D.; Coster, D.; Fuenfgelder, H.; Jacquot, J.; Ochoukov, R.; Silva, A.; Colas, L.; Křivská, A.

doi:10.1088/1741-4326/aa7f47

Cited by 18 publications

(19 citation statements)

References 25 publications

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“…The second simulation strategy is of the ab-initio type, and it requires to interface several codes in a consistency loop [13]. Before starting the iterative loop, EMC3-EIRENE simulations are done for a phase of the plasma discharge without RF, and thus without E×B drifts induced by ICRF.…”

Section: Icrf Induced Plasma Convectionmentioning

confidence: 99%

Plasma edge modelling with ICRF coupling

et al. 2017

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Abstract. The physics of Radio-Frequency (RF) wave heating in the Ion Cyclotron Range of Frequencies (ICRF) in the core plasmas of fusion devices are relatively well understood while those in the Scrape-Off Layer (SOL) remain still unresolved. This paper is dedicated to study the ICRF interactions with the plasma edge, mainly from the theoretical and numerical point of view, in particular with the 3D edge plasma fluid and neutral transport code EMC3-EIRENE and various wave codes. Here emphasis is given to the improvement of ICRF coupling with local gas puffing and to the ICRF induced density convection in the SOL.

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Section: Icrf Induced Plasma Convectionmentioning

confidence: 99%

Plasma edge modelling with ICRF coupling

et al. 2017

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“…Paper [2] defined a private SOL surrounded by the two antenna limiters on figure 1. References [16], [18] investigated waves in presence of RF-induced density modifications.…”

Section: Rf Wave Propagation Module For Tokamaksmentioning

confidence: 99%

“…The density changes in turn alter the RF wave propagation and subsequent sheath rectification. To model this process self-consistently for AUG antennas, the SSWICH-SW asymptotic code was iterated with RAPLICASOL and EMC3-EIRENE 3D SOL code for density transport [18], [19]. In EMC3, V DC was assumed homogeneous along the open field lines.…”

Section: Rf-induced Local Density Modificationsmentioning

confidence: 99%

SOL RF physics modelling in Europe, in support of ICRF experiments

Colas

Jacquot

et al. 2017

EPJ Web Conf.

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Abstract.A European project was undertaken to improve the available SOL ICRF physics simulation tools and confront them with measurements. This paper first reviews code upgrades within the project. Using the multi-physics finite element solver COMSOL, the SSWICH code couples RF full-wave propagation with DC plasma biasing over "antenna-scale" 2D (toroidal/radial) domains, via non-linear RF and DC sheath boundary conditions (SBCs) applied at shaped plasma-facing boundaries. For the different modules and associated SBCs, more elaborate basic research in RF-sheath physics, SOL turbulent transport and applied mathematics, generally over smaller spatial scales, guides code improvement. The available simulation tools were applied to interpret experimental observations on various tokamaks. We focus on robust qualitative results common to several devices: the spatial distribution of RF-induced DC bias; left-right asymmetries over strap power unbalance; parametric dependence and antenna electrical tuning; DC SOL biasing far from the antennas, and RF-induced density modifications. From these results we try to identify the relevant physical ingredients necessary to reproduce the measurements, e.g. accurate radiated field maps from 3D antenna codes, spatial proximity effects from wave evanescence in the near RF field, or DC current transport. Pending issues towards quantitative predictions are also outlined. ICRF antennas as active PlasmaFacing ComponentsThe phased strap arrays used to launch Ion Cyclotron Range of Frequency (ICRF, 30-80MHz) waves into magnetic fusion devices poorly radiate in vacuum: efficient coupling of the fast wave to the main plasma necessitates minimizing the distance from the straps to a critical peripheral density: the R-cutoff layer. In the Scrape-Off Layer (SOL) the antennas then behave as Plasma-facing Components (PFCs), subject to PlasmaSurface Interactions (PSI). As RF-field-emitting structures, ICRF antennas are active PFCs able to create RF-specific PSI and to modify locally their environment: enhanced ion energies, heat loads, erosion and density modifications have been observed locally. These phenomena are critical in the prospect of long-pulse machines with high-Z plasma-facing materials. Predicting the magnitude and spatial location of these processes, in relation with plasma parameters, launcher design and electrical settings, remains challenging. So far, realistic tokamak predictions relied on very simple models of oscillating double probes. A European project was undertaken to improve the available SOL RF physics simulation tools and confront them with measurements. This paper first reviews code improvements and associated basic research within the project. The available simulation tools are then applied to interpret experimental observations on various machines. From these results we exhibit qualitative properties common to the various devices, identify relevant physical ingredients necessary to reproduce the measurements, as well as pending issues towards quantitative predictions. I...

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“…It is important to understand the behaviour of Ion Cyclotron Range of Frequencies (ICRF) waves in edge plasmas and near the antenna, in order to understand the physical mechanisms underlying experimental observations such as ion sputtering [1,2], RF induced convection [3], and variation in power coupling to the plasma.…”

Section: Introductionmentioning

confidence: 99%

3-Dimensional density profiles in edge plasma simulations for ICRF heating

et al. 2017

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Abstract. In this paper we discuss improvements made to two codes for the simulation of ICRF waves in edge plasmas: SSWICH-SW, which self-consistently models the interplay between sheath physics and radiofrequency waves (the slow wave), and RAPLICASOL, a Finite Element solver for Maxwell's equations in the cold plasma approximation. We have extended both to be able to handle 3D plasma density profiles. A comparison between a 1D and a 3D simulation reveals that the density profile dimensionality has a relatively small effect on E at the aperture, but a large effect on the sheath potential at the antenna limiters

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Radio frequency heating induced edge plasma convection: self-consistent simulations and experiments on ASDEX Upgrade

Cited by 18 publications

References 25 publications

Plasma edge modelling with ICRF coupling

Plasma edge modelling with ICRF coupling

SOL RF physics modelling in Europe, in support of ICRF experiments

3-Dimensional density profiles in edge plasma simulations for ICRF heating

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