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Crack Characteristic Measurement in Beryllium after Thermal Shock

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Rare Metals 1998年第1期17卷 17-22页

作者：钱蓉晖 Farschungszentrum Juelich euratom-association 德国

he numbers and distribution of cracks in bulk beryllium which was loaded by intense electron beam were observed by optical image analysis, where the crack characteristic measurement and analysis were performed. The results show that: 1) The crack numbers in TR30 of beryllium with fine grain size and relatively high Beo content (no more than 3%) are about 2～4 times more than that in DShG200 of beryllium, whose grain size is larger but Beo content is less than 0.8%, under the same electron beam loading conditions, the ceramic phase of Beo in beryllium makes beryllium more brittle. 2) The successive electron pulse irradiation results in the wider cracks since the cracks formed by the former shot might be enlarged by following shots. The reason might be that there was a stress concentration at original cracks when the second shot came and so that thermal stress raised. DShG200 exhibit the better thermal shock resistance than that of TR30.

关键词： Crack distribution Image analysis Plasma facing materials Thermal shock resistance

Development of Powerful RF Plasma Sources for Present and Future NBI Systems

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Plasma Science and Technology 2004年第1期6卷 2135-2140页

作者： E.Speth NBI-Team Max-Planck-Institut fiir Plasmaphysik 85748 Garching Germany EURATOM-AssociationMax-Planck-Institut fiir Plasmaphysik 85748 Garching Germany EURATOM-Association

This paper deals with the topic of RF plasma sources and their application inhigh-power neutral beam heating systems for nuclear fusion devices. RF sources represent aninteresting alternative to the conventional arc discharge sources. Due to the absence of hotfilaments they exhibit an inherent simplicity both in mechanical and electrical aspects andconsequently offer advantages in terms of cost savings, gain in availability and reliability andreduced maintenance. This renders the RF plasma source attractive for any long pulse (> 10 sec) NBIsystem and in particular for the ITER NBI system. The latter, however, requires that the RF plasmasource is also capable of delivering negative rather than positive hydrogen ions. In the first partof the paper the types, characteristics and operation experience of RF plasma sources for positiveions in operation are described. The second part is devoted to the development for ITER NBI: thebasic requirements, physics and technology issues and the present status are discussed.

关键词： neutral beam injection negative ions RF plasma source

Surface Configuration of Be Irradiated by Intense Electron Beam

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Rare Metals 1998年第1期17卷 42-50页

作者：钱蓉晖 Forschungszentrum Juelich Euratom-association 德国

eryllium is one of the candidates of plasma facing materials (PFMs). Its behavior under thermal load is highly concerned. The thermal shock test for 5 kinds of Be was performed at JUDITH (Juelich diverter test facility in hot cell), KFA. The surface configuration of the Be samples which were loaded by intense electron beam in JUDITH was measured by using profilometer. The surface configuration characteristic of different Be samples under different thermal load condition are discussed.

关键词： Surface configuration Thermal shock Beryllium

The role of zonal flows in reactive fluid closures

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Plasma Science and Technology 2018年第7期20卷 41-49页

作者： jan weiland chalmers university of technology and euratom-vr association SE-41296 GothenburgSweden

We will give an overview of results obtained by our reactive fluid model. It is characterised as a fluid model where all moments with sources in the experiment are kept. Furthermore, full account is taken for the highest moments appearing in unexpanded denominators also including full toroidicity. It has been demonstrated that the strength of zonal flows is dramatically larger in reactive fluid closures than in those which involve dissipation. This gives a direct connection between the fluid closure and the level of excitation of turbulence. This is because zonal flows are needed to absorb the inverse cascade in quasi 2D turbulence. This also explains the similarity in structure of the transport coefficients in our model with a reactive closure in the energy equation and models which have a reactive closure because of zero ion temperature such as the Hasegawa-Wakatani model. our exact reactive closure unifies several well-known features of tokamak experiments such as the L-H transition, internal transport barriers and the nonlinear Dimits upshift of the critical gradient for onset of transport. It also gives transport of the same level as that in nonlinear gyrokinetic codes. Since these include the kinetic resonance this confirms the validity of the thermodynamic properties of our model. Furthermore, we can show that while a strongly nonlinear model is needed in kinetic theory a quasilinear model is sufficient in the fluid description. Thus our quasilinear fluid model will be adequate for treating all relevant problems in bulk transport. This is finally confirmed by the reproduction by the model of the experimental power scaling of the confinement time Te ~ P-2/3. This confirms the validity of our reactive fluid model. This also gives credibility to our ITER simulations including the H-mode barrier. A new result is here, that alpha heating strongly reduces the slope of the H-mode barrier. This should significantly reduce the effects of ELM＇s.

关键词： turbulent transport improved mixing length estimates zonal flows toroidicity

observation of Blobs and Holes in the Boundary Plasma of EAST Tokamak

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Plasma Science and Technology 2011年第4期13卷 410-414页

作者：颜宁徐国盛张炜常加峰王亮刘少承刘鹏汪惠乾蒋敏熊豪丁斯晔万宝年高翔 V.NAULIN A.H.NIELSEN J.JuulRASMUSSEN Institute of Plasma Physics Chinese Academy of Sciences association euratom-Risφ DTU

Intermittent convective transport at the edge and in the scrape-off layer （SoL） of EAST was investigated by using fast reciprocating Langmuir probe. Holes, as part of plasma structures, were detected for the first time inside the shear layer. The amplitude probability distribution function of the turbulence is strongly skewed, with positive skewed events （＂blobs＂） prevailing in the SoL region and negative skewed events （＂holes＂） dominant inside the shear layer. The statistical properties coincide with previous observations from JET. The generation mechanism of blobs and holes is also discussed. In addition burst structure and dynamics character of them are also presented.

关键词： intermittent transport blobs holes generation mechanism dynamics character

Progress Toward Steady-State operation on Tore Supra

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Plasma Science and Technology 2004年第1期6卷 2101-2108页

作者： J.Jacquinot G.T.Hoang on behalf of the Tore Supra Team euratom-CEA association CEA/DSM/DRFC CEA Cadarache F-13108 Saint-Paul-Lez-Durance FranceEuratom-CEA Association CEA/DSM/DRFC CEA Cadarache F-13108 Saint-Paul-Lez-Durance FranceEuratom-CEA Association CEA/DSM/DRFC CEA Cadarache F-13108 Saint-Paul-Lez-Durance France

Important technological and physics issues related to steady-state operationrequired for next step are being examined on Tore Supra, after a major upgrade of internalcomponents in order to increase the heat extraction capability to 25 MW for 1000 s. Here, we showfirst experimental results, where all the plasma facing components were actively cooled duringpulses exceeding four minutes, with reactor-relevant heat load. New physics was observed innon-inductively driven plasmas, including a stationary peaked radial profile of the plasma densitygenerated by an anomalous inward pinch; and a regime characterized by sinusoidal oscillations ofcentral electron temperature, governed by non-linear coupling between heat transport and plasmacurrent analogous to a predator-prey mechanism.

关键词： steady-state operation tore supra, non-inductively driven plasma

Kinetics of Hydrogen Molecules in MAGNUM-PSI

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Plasma Science and Technology 2008年第2期10卷 162-169页

作者： M.BAEVA W.J.GoEDHEER N.J.LoPES CARDoZo Leibniz Institute for Plasma Science and Technology Felix-Hausdorf-Str. 2 D-17489 Greifswald Germany FoM-Institute for Plasma Physics Rijnhuizen Association EURATOM-FOM Trilateral Euregio Cluster P. O. Box 1207 3430 BE Nieuwegein The Netherlands

Results from simulations of plasma and neutrals under conditions predictively characterizing the detached plasma regime in the linear machine MAGNUM-PSI are presented. The relaxation of the vibrationally excited hydrogen molecules is investigated in order to establish a relation between their relaxation and dwell times, and the role of the varions mechanisms of the molecular vibrational kinetics. Tile results obtained show that the individual vibrational states have to be inclllded in the transport code for neutrals as distinct species, since the relaxation time of tile vibrational states is sufficiently longer than the typical dwell time of hydrogen molecules in the detached plasma region. The parameters of plasma and neutrals are affected by the transport of the vibrationally excited hydrogen lnolecnles. Furthermore. the rate of molecular reconlbination is overestimated by a factor of - 5 provided that the transport of ilydrogen molecules only in their ground vibrational state is considered. The role of the various processes of vibrational kinetics is studied. The vibrational excitation through singlet electronic states ires a strong influence on the molecular densities for levels with vibrational quantum numbers v≥ 5. Vibration-vibration （V-V） collisions between vibrationally excited hydrogen molecules and vibration-translation （V-T） collisions between vibrationally excited hydrogen molecules and ground state molecules and atoms are of nlinor importance in MAGNUM-PSI.

关键词： vibrational relaxation hydrogen molecules. B2-Eirene simulation detached plasma

Reciprocating Probe Measurements of L-H Transition in LHCD H-Mode on EAST

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Plasma Science and Technology 2013年第7期15卷 619-622页

作者：刘鹏徐国盛汪惠乾蒋敏王亮张炜刘少承颜宁丁斯晔 Institute of Plasma Physics Chinese Academy of Sciences association euratom-DTU Physics DepartmentDK-4000 Roskilde Denmark

As the power available in the initial phase of the ITER operation will be limited, accessing the high confinement mode （H-mode） with low heating power will be a critical issue. In the recent experiment on EAST, the H-mode was obtained for the first time with lower hybrid current drive （LHCD） wave only. Reciprocating Langmuir probe measurements at the outer midplane showed that the electron density ne and electron tempel：ature Te in the scrape-off layer （SoL） were significantly reduced in the ELM-free phase, resulting in the increase of lower-hybrid wave （LHW） reflection. It was found that the power loss Ploss was comparable during the L-H transition, by comparing the adjacent L-mode and H-mode discharge. The Da emission, Te and ne decreased rapidly in the time scale of about 1 ms, and the radial electric field Er turned positive in this process near the last closed flux surface. Multiple L-H-L transitions were observed during a single shot when the applied LHW power was marginal to the threshold. The floating potential （Vf） had negative spikes corresponding with the Da signal, and Er oscillation evolved into several intermittent negative spikes just before the L-H transition. In some shots, dithering was observed just before the L-H transition.

关键词： L-H transition reciprocating probe dithering

The Runaway Generation and Disruptive Instability in the istToK Tokamak

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中国核科技报告 1999年第S4期 385-386页

作者： V.V.Plyusnin J.A.C.Cabral H.Figueiredo C.A.F.Varandas I.S.Nedzel‘skij 1049-001 Lisboa PoRTUGAL association euratom/ist Centro de Fuso Nuclear Instituto Superior Técnico Av.Rovisco Pais

The runaway generation is one of the fundamental physical processes in plasmas being under the action of external electric fields. This phenomenon has been intensively studied both experimentally and theoretically. Ho... 详细信息

关键词： The Runaway Generation and Disruptive Instability in the istToK Tokamak