Effect of plasma configuration on carbon migration measured in the inner divertor of JET using quartz microbalance

Esser, H. G.; Philipps, V.; Freisinger, M.; Matthews, G. F.; Coad, J. P.; Neill, G. F.

doi:10.1016/j.jnucmat.2004.10.112

Cited by 34 publications

(36 citation statements)

References 12 publications

(13 reference statements)

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“…Previously reported QMB measurements in the inner louvre show a clear dependence of deposition rates on the position of the inner SP, with highest values when the SP is positioned at the horizontal target with line-of-sight to the QMB position [25]. Measurements by the inner QMB during JET campaign [2005][2006][2007] confirm these findings (Fig.…”

Section: Influence Of Magnetic Field and Divertor Geometry On Erosionsupporting

confidence: 67%

“…The corresponding deposition rates measured by the inner QMB are up to ~4 times higher than in cases when the corresponding target positions were conditioned in previous discharges [25,37]. The so-called "shot history effect" is attributed to enhanced erosion of layers deposited in previous discharges.…”

Section: Erosion Induced By Variations Of Strike Point Positionsmentioning

confidence: 97%

“…An increase of erosion of the target in the inner divertor of JET during H-mode operation with respect to the L-mode has been reported [25]. A systematic study and comparison of the deposition data in the inner and outer divertor louvres have become possible after an upgrade of the QMB system.…”

Section: Surface Layers and Elm-induced Enhanced Erosionmentioning

confidence: 97%

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Dynamics of erosion and deposition in tokamaks

Kreter

Brezinsek

Coad

et al. 2009

Journal of Nuclear Materials

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In recent years, a general qualitative understanding has been reached about the major pathways of material migration in divertor tokamaks. Main chamber wall components have been identified as the major source of material erosion. The eroded material is transported by scrape-off layer flows, in the case of the ion B×∇B drift pointing towards the X-point, predominately towards the inner divertor leg, where it is deposited in the form of amorphous layers. On JET, where carbon is the main plasma-facing material, it has been found that the presence of deposited carbon rich layers determines the dynamic characteristics of further redistribution of carbon, in particular towards remote areas. The transport from the strike point to the deposition location is mainly line-of-sight. The amount of eroded carbon depends on the surface type, with lower rates for the bare CFC and higher rates for deposited layers. The erosion rates in the inner divertor increase non-linearly with increasing ELM energies.

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Section: Influence Of Magnetic Field and Divertor Geometry On Erosionsupporting

confidence: 67%

Section: Erosion Induced By Variations Of Strike Point Positionsmentioning

confidence: 97%

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Dynamics of erosion and deposition in tokamaks

Kreter

Brezinsek

Coad

et al. 2009

Journal of Nuclear Materials

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“…Eventually, the retained fuel will be localised in areas not accessible to the divertor plasma flux. Such process has been well documented in JET experiments with Quartz Microbalance monitors (QMB) [434] near the inner divertor corner, whose results for the whole experimental campaigns in the period of three years operation with the JET MkIIGB divertor are shown in Fig. 4.2.6-1.…”

Section: Fuel Retention Mechanisms In Present Devices and Implicationmentioning

confidence: 68%

Chapter 4: Power and particle control

Loarte¹,

et al. 2007

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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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“…average kinetic energy of impinging ions on the JET Mark IIa divertor surface ~ 30 eV [243]. Particularly thick soft deposits (up to 40 µm) with high hydrogen content (D+T) / C = 0.7 were found on the water cooled louvre at the entrance of the inner divertor pump duct shadowed from the plasma already after a short operation period of JET in 1996 [244,245], which indicates that diagnostic observational access to the divertor plasma from these regions, as e.g. foreseen in W7-X, will most likely require the integration of a window cleaning technique.…”

Section: Contamination Of Diagnostic Windowsmentioning

confidence: 99%

Diagnostics for steady state plasmas

Hartfuß¹,

König²,

Werner³

2006

Plasma Phys. Control. Fusion

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Problems related to the development of diagnostics for steady state fusion plasma experiments are being discussed. The paper concentrates on those necessities already appearing in nowadays non-burning plasma fusion experiments when extending pulse lengths beyond 10 s, i.e. thermal load, erosion, deposition, and long-time signal integration in magnetic diagnostics. Problems arising from high power ECRH under conditions of incomplete absorption are outlined. Individual standard diagnostic systems are discussed to identify their specific problems as well as the opportunities connected with long pulse operation. Burning plasma experiments characterized by intense n-and g-radiation are briefly reviewed for reasons of completeness, dealing with radiation induced processes in windows, fibres, cables, and mirrors. Methods of data handling, real time monitoring, and plasma control are outlined. Index

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Effect of plasma configuration on carbon migration measured in the inner divertor of JET using quartz microbalance

Cited by 34 publications

References 12 publications

Dynamics of erosion and deposition in tokamaks

Dynamics of erosion and deposition in tokamaks

Chapter 4: Power and particle control

Diagnostics for steady state plasmas

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