Spectroscopic investigation of the dynamics of ions and neutrals in the ASDEX Upgrade Divertor II

Gafert, J.; Behringer, K.; Coster, D.; Dorn, C.; Kallenbach, A.; Schneider, Robert; Schumacher, U.

doi:10.1016/s0022-3115(98)00668-0

Cited by 22 publications

(22 citation statements)

References 4 publications

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“…Impurities migrate for longer distances if they leave the divertor region either as neutral atoms or ions pulled out of the divertor by the thermal force. Impurity ion flow velocities in the range of 20 km/s (out of the divertor) have been observed [120,280], with the magnitude agreeing with UEDGE calculations [281]. These impurities are eventually deposited at some distance from the strike point.…”

Section: Materials Migrationsupporting

confidence: 67%

Chapter 4: Power and particle control

Divertor¹,

Database²,

Editors³

1999

Nucl. Fusion

280

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Abstract.Progress, since the ITER Physics Basis publication, in understanding the processes that will determine the properties of the plasma edge and its interaction with material elements in ITER is described. Experimental areas where significant progress has taken place are : energy transport in the SOL in particular of the anomalous transport scaling, particle transport in the SOL that plays a major role in the interaction of diverted plasmas with the main chamber material elements, ELM energy deposition on material elements and the transport mechanism for the ELM energy from the main plasma to the plasma facing components, the physics of plasma detachment and neutral dynamics including the edge density profile structure and the control of plasma particle content and He removal, the erosion of low and high Z materials in fusion devices, their transport to the core plasma and their migration at the plasma edge including the formation of mixed materials, the processes determining the size and location of the retention of tritium in fusion devices and methods to remove it and the processes determining the efficiency of the various fuelling methods as well as their development towards the ITER requirements. This experimental progress has been accompanied by the development of modelling tools for the physical processes at the edge plasma and plasma-materials interaction and the further validation of these models by comparing their predictions with the new experimental results. Progress in the modelling development and validation has been mostly concentrated in the following areas : refinement of the predictions for ITER with plasma edge modelling codes by inclusion of detailed geometrical features of the divertor and the introduction of physical effects, which can play a 2 major role in determining the divertor parameters at the divertor for ITER conditions such as hydrogen radiation transport and neutral-neutral collisions, modelling of the ion orbits at the plasma edge, which can play a role in determining power deposition at the divertor target, models for plasma-materials and plasma dynamics interaction during ELMs and disruptions, models for the transport of impurities at the plasma edge to describe the core contamination by impurities and the migration of eroded materials at the edge plasma and its associated tritium retention and models for the turbulent processes that determine the anomalous transport of energy and particles across the SOL. The implications for the expected performance of the reference regimes in ITER, the operation of the ITER device and the lifetime of the plasma facing materials are discussed. Introduction.This chapter outlines the significant progress achieved since the ITER Physics Basis in understanding basic scrape-off layer (SOL) and divertor processes in a tokamak. The interaction of plasma with first-wall surfaces will have considerable impact on the performance of fusion plasmas, the lifetime of plasma facing components, and the retention of tritium in next step Burning Plasma E...

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Section: Materials Migrationsupporting

confidence: 67%

Chapter 4: Power and particle control

Divertor¹,

Database²,

Editors³

1999

Nucl. Fusion

280

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“…128). In contrast, the net recombination zone is characterised by quite small flow velocities, as measured with a sophisticated toroidally viewing spectroscopy system [157], giving the plasma enough time to recombine (Fig. 129).…”

Section: Detachment Propertiesmentioning

confidence: 99%

“…Also, the carbon residence time in the separatrix-near region is large, because the carbon ion mass flow pattern (Fig. 138) shows a flow reversal zone due to the ion thermal force with small flow velocities close to the separatrix and a forward flow in the outer scrape-off layer with relatively fast flow [157].…”

Section: Divertor Power Loadmentioning

confidence: 99%

Plasma Edge Physics with B2‐Eirene

Schneider

Bonnin

Borraß

et al. 2006

Contrib. Plasma Phys.

Self Cite

478

426

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The B2‐Eirene code package was developed to give better insight into the physics in the scrape‐off layer (SOL), which is defined as the region of open field‐lines intersecting walls. The SOL is characterised by the competition of parallel and perpendicular transport defining by this a 2D system. The description of the plasma‐wall interaction due to the existence of walls and atomic processes are necessary ingredients for an understanding of the scrape‐off layer. This paper concentrates on understanding the basic physics by combining the results of the code with experiments and analytical models or estimates. This work will mainly focus on divertor tokamaks, but most of the arguments and principles can be easily adapted also to other concepts like island divertors in stellarators or limiter devices. The paper presents the basic equations for the plasma transport and the basic models for the neutral transport. This defines the basic ingredients for the SOLPS (Scrape‐Off Layer Plasma Simulator) code package. A first level of understanding is approached for pure hydrogenic plasmas based both on simple models and simulations with B2‐Eirene neglecting drifts and currents. The influence of neutral transport on the different operation regimes is here the main topic. This will finish with time‐dependent phenomena for the pure plasma, so‐called Edge Localised Modes (ELMs). Then, the influence of impurities on the SOL plasma is discussed. For the understanding of impurity physics in the SOL one needs a rather complex combination of different aspects. The impurity production process has to be understood, then the effects of impurities in terms of radiation losses have to be included and finally impurity transport is necessary. This will be introduced with rising complexity starting with simple estimates, analysing then the detailed parallel force balance and the flow pattern of impurities. Using this, impurity compression and radiation instabilities will be studied. This part ends, combining all the elements introduced before, with specific, detailed results from different machines. Then, the effect of drifts and currents is introduced and their consequences presented. Finally, some work on deriving scaling laws for the anomalous turbulent transport based on automatic edge transport code fitting procedures will be described. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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“…While a uniform-illumination calibration image is unavailable at the moment, it appears that the lower right region of the image field is not illuminated by the plasma and there is evidence of vignetting in the outer regions of the image. A two or three-point median filter is usually applied to suppress radiation-induced noise and the brightness projection [see equation (6)] is extracted by boxcar smoothing vertically using a window of width equal to the fringe period (11 pixels in this case). To improve signal to noise ratio, the image is often binned by a factor of two prior to demodulation.…”

Section: Image Processing and Demodulationmentioning

confidence: 99%

“…While a broad understanding of the key physical issues has been established, there are inconsistencies between modeling of carbon ion flows (indicative of convective heat fluxes) into the divertor during detachment and mach probe measurements in the outer scrape-off-layer [4]. Carbon ion flow measurements on DIII-D based on visible Doppler spectroscopy using an array of discrete lines of sight and grating spectrometers have also been reported previously [5,6]. Because of the uncertainty in the spatially-dependent brightness-weighting, sophisticated spectrum-fitting routines that take account of Zeeman effect broadening must be employed to extract flows and temperatures, and the resulting estimates can have large uncertainties.…”

Section: Introductionmentioning

confidence: 99%

Coherence Imaging of Flows in the DIII‐D Divertor

Howard

Diallo

Creese

et al. 2011

Contrib. Plasma Phys.

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Various spatial heterodyne polarization interferometers for spectrally-resolved optical imaging of edge and core parameters in high temperature magnetized plasmas are described. Applications for such "coherence imaging" (CI) systems include imaging motional Stark effect and Zeeman effect polarimetry for determination of the magnetic field pitch angle, and passive and active (charge exchange recombination spectroscopy -CXRS) Doppler imaging of plasma temperature and flow. In this paper we describe spatial heterodyne coherence imaging systems and present first results of Doppler flow imaging in the DIII-D divertor.Instruments have been installed for imaging flows in the divertor and scrape-off-layer in the DIII-D tokamak and also for Doppler imaging on the H-1 heliac [1]. In the former case, single snapshot interferometric images of the plasma in CII 514nm, and CIII 465nm emission have been demodulated to obtain flow and ion temperature projections in both the scrape-off-layer and divertor. Flow field amplitudes in the divertor are found to be broad agreement with UEDGE modeling [2], and point the way towards experiments that address important divertor transport issues in future.

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Spectroscopic investigation of the dynamics of ions and neutrals in the ASDEX Upgrade Divertor II

Cited by 22 publications

References 4 publications

Chapter 4: Power and particle control

Chapter 4: Power and particle control

Plasma Edge Physics with B2‐Eirene

Coherence Imaging of Flows in the DIII‐D Divertor

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