Overview of progress in European medium sized tokamaks towards an integrated plasma-edge/wall solution

Integrating the plasma core performance with an edge and scrape-off layer (SOL) that leads to tolerable heat and particle loads on the wall is a major challenge. The new European medium size tokamak task force (EU-MST) coordinates research on ASDEX Upgrade (AUG), MAST and TCV. This multi-machine approach within EU-MST, covering a wide parameter range, is instrumental to progress in the field, as ITER and DEMO core/pedestal and SOL parameters are not achievable simultaneously in present day devices. A two prong approach is adopted. On the one hand, scenarios with tolerable transient heat and particle loads, including active edge localised mode (ELM) control are developed. On the other hand, divertor solutions including advanced magnetic configurations are studied. Considerable progress has been made on both approaches, in particular in the fields of: ELM control with resonant magnetic perturbations (RMP), small ELM regimes, detachment onset and control, as well as filamentary scrape-off-layer transport. For example full ELM suppression has now been achieved on AUG at low collisionality with n  =  2 RMP maintaining good confinement ${{H}_{\text{H}\left(98,\text{y}2\right)}}\approx 0.95$ . Advances have been made with respect to detachment onset and control. Studies in advanced divertor configurations (Snowflake, Super-X and X-point target divertor) shed new light on SOL physics. Cross field filamentary transport has been characterised in a wide parameter regime on AUG, MAST and TCV progressing the theoretical and experimental understanding crucial for predicting first wall loads in ITER and DEMO. Conditions in the SOL also play a crucial role for ELM stability and access to small ELM regimes

Operating a full tungsten actively cooled tokamak: overview of WEST first phase of operation

WEST is an MA class superconducting, actively cooled, full tungsten (W) tokamak, designed to operate in long pulses up to 1000 s. In support of ITER operation and DEMO conceptual activities, key missions of WEST are: (i) qualification of high heat flux plasma-facing components in integrating both technological and physics aspects in relevant heat and particle exhaust conditions, particularly for the tungsten monoblocks foreseen in ITER divertor; (ii) integrated steady-state operation at high confinement, with a focus on power exhaust issues. During the phase 1 of operation (2017–2020), a set of actively cooled ITER-grade plasma facing unit prototypes was integrated into the inertially cooled W coated startup lower divertor. Up to 8.8 MW of RF power has been coupled to the plasma and divertor heat flux of up to 6 MW m−2 were reached. Long pulse operation was started, using the upper actively cooled divertor, with a discharge of about 1 min achieved. This paper gives an overview of the results achieved in phase 1. Perspectives for phase 2, operating with the full capability of the device with the complete ITER-grade actively cooled lower divertor, are also described

Über den Zusammenhang von Kommunikation und Lernen im schulischen Kontext. Ein Modell Kommunikationsorientierter Schulsozialarbeit auf der Grundlage der Gewaltfreien Kommunikation von Marshall B. Rosenberg

Zum ersten geht es um die Leitfrage, wie Schulsozialarbeit dazu beitragen kann, dass Schulbildung nicht nur für einen anpassungsbereiten Teil der Schüler/innen Teilhabe befördert, sondern auch diejenigen erreicht, die dazu neigen, sich von ihr abzuwenden. Hierfür wird im ersten Teil der Arbeit zunächst untersucht, wie Lernen aus neurobiologischer, pädagogischer und psychologischer Perspektive verstanden werden kann, welche Faktoren Lernprozesse begünstigen bzw. hemmen und wie die subjektive Tätigkeit des Lernens auf schulisch-gesellschaftlicher Ebene in einen Kanon des Lernens einfließt. In den beiden darauffolgenden Kapiteln werden zunächst wesentliche Aspekte der zwischenmenschlichen Kommunikation mit Bezug auf psychologisch-soziologische Kommunikationstheorien umrissen und anschließend zu dem Sachverhalt übergeleitet, dass jedes Lernen immer auch eine komplexe Kommunikationsleistung ist. Neben der Relevanz, Kommunikation in der Schule zu thematisieren, wird darin ebenso aufgezeigt, an welcher Stelle der Kommunikationsbegriff in der Schul- und Sozialpädagogik an eine Grenze gelangt. Innerhalb der zweiten Kernfrage wird betrachtet, wie eine Kooperation von Schule und Jugendhilfe idealer Weise aussehen könnte, in der die wissenschaftlichen Erkenntnissen zu Lernverläufen offensiv einbezogen werden. Dem liegt eine Analyse des deutschen allgemeinbildenden Schulwesens zu Grunde. Hierin wird die Schulpflicht und auch die Selektivität, welche mit der Einführung verschiedener Schulformen einhergeht, in deren historischen Wurzeln betrachtet, worin einzelne Wellen der Bildungsreformen ersichtlich werden. Vertiefend dazu wird aufgezeigt, welche Faktoren Bildungsreformen begünstigten bzw. hervorriefen und welche Kräfte dem horizontalen Schulwesen in Deutschland und damit der Verringerung des selektiven Gehalts von Schule, entgegen wirkten. Denn Inklusionsleistungen, zu denen Schulsozialarbeit unter anderem berufen ist, finden keinen Bedarf, wenn nicht vorher eine Exklusion stattfand. Welche Möglichkeiten Schulsozialarbeit für allgemeinbildende Schulen dahingehend eröffnen kann, sich inhaltlich und methodisch anzureichern, weiterzuentwickeln, zu öffnen und zu vernetzen, sowie ein Blick auf die Herausforderungen für eine gegenseitig integrierende Kooperation, wird im darauffolgenden Teil, im Hinblick auf eine Charakterisierung von Schulsozialarbeit aufgezeigt. Dem folgt ein Einblick in das Konzept der Gewaltfreien Kommunikation, und daran anschließend ein Rahmenkonzept Kommunikationsorientierter Schulsozialarbeit. Dieses verbindet wissenschaftliche Erkenntnisse zu Lernverläufen und das Konzept der Gewaltfreien Kommunikation mit den ermittelten Schwachstellen von Schule, was schließlich einen ideellen Ausblick über sozialpädagogische Handlungsfelder in der Schule gibt. Und letztendlich schließt die Arbeit mit einer schlussfolgernden Zusammenfassung ab.The first central question is about, what schoolsocialwork could contribute to the actual school-situation, that not only adaptionable pupils getting reached, but also those ones, whose are tended to anticipate themselves from school. Therefore in the first part of the work gets analyzed, how learning out of the perspective of neurobiology, education and psychology can be understood, which factors are suppporting respectively blocking learning-processes and how the subjective learning-activity is connected to the school-societal-level. In the both following chapters initially it gets outlined main aspects of the interpersonal communication related to psychologic-sociological communication-theories, bridging to the point where every learning also is a complex communication-activity. Next to the relevance to broach the issue of communication in school, it also gets illustrated on which point the communication-term is coming to a border within the school- and social pedagogy. Inside the second central question gets considered how an ideal cooperation of school and youth welfare can look like, wherein the scientific knowledge to learning-processes offensive getting included. The analysis of the german, general-education-system is the first base therefor. Herein gets regarded the historical roots of the school-obligation and also the selectivity, which results automatically out of different kindes of schools. This showes single waves of education-reformes. Deepening to that it gets demonstrated which factors were supporting respectively effecting education-reformes and which power was working against the horizontal school-system in Germany, and therein working against the reduction of the selective content of school. Because inclusion-activities, to which schoolsocialwork is appointed, does not have a necessity, if not before happened an exclusion. Which possibilities schoolsocialwork can develop for general-education-schools, to get with regard to contents and methodes enriched, advanced, opened up and linked, as well as building up a mutual integrative cooperation, gets brought out in the following part within a characterisation of schoolsocialwork. Thereafter it is about to gain inside the concept of nonviolent communiation which followes a frame-concept of communication-oriented schoolsocialwork. These connects scientific findings of learning processes and the concept of the nonviolent communication with the determined weak points of school, which gives finally an forecast about social pedagogic spheres of activity in schools. And eventual the work is closing with a deductive abstraction

On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

Modelling of the effect of ELMs on fuel retention at the bulk W divertor of JET

Effect of ELMs on fuel retention at the bulk W target of JET ITER-Like Wall was studied with multi-scale calculations. Plasma input parameters were taken from ELMy H-mode plasma experiment. The energetic intra-ELM fuel particles get implanted and create near-surface defects up to depths of few tens of nm, which act as the main fuel trapping sites during ELMs. Clustering of implantation-induced vacancies were found to take place. The incoming flux of inter-ELM plasma particles increases the different filling levels of trapped fuel in defects. The temperature increase of the W target during the pulse increases the fuel detrapping rate. The inter-ELM fuel particle flux refills the partially emptied trapping sites and fills new sites. This leads to a competing effect on the retention and release rates of the implanted particles. At high temperatures the main retention appeared in larger vacancy clusters due to increased clustering rate