High power neon seeded JET discharges: Experiments and simulations

A series of neon seeded JET ELMy H-mode pulses is considered from the modeling as well as from the experimental point of view. For two different Ne seeding rates and two different D puffing gas levels the heating power, P heat , is in the range 22–29.5 MW. The main focus is on the numerical reconstruction of the total radiated power (which mostly depends on the W concentration) and its distribution between core and divertor and of Z eff(which mostly depends on the Ne concentration). To model self-consistently the core and the SOL two input parameters had to be adjusted case by case: the SOL diffusivity, D SOL , and the core impurity inward pinch, v pinch . D SOL had to be increased with increasing Ne and the level of v pinch had to be changed, for any given Ne , according to the level of P heat : it decreases with increasing P heat . Since the ELM frequency, f ELM , is experimentally correlated with P heat , (it increases with P heat ) the impurity inward pinch can be seen as to depend on f ELM . Therefore, to maintain a low v pinch level (i.e. high f ELM ) Ne / P heat should not exceed a certain threshold, which slightly increases with the D puffing rate. This might lead to a limitation in the viability of reducing the target heat load by Ne seeding at moderate D , while keeping Z effat acceptably low level.EURATOM 63305

Application of the VUV and the soft x-ray systems on JET for the study of intrinsic impurity behavior in neon seeded hybrid discharges

This paper reports on impurity behavior in a set of hybrid discharges with Ne seeding—one of the techniques considered to reduce the power load on reactor walls. A series of experiments carried out with light gas injection on JET with the ITER-Like-Wall (ILW) suggests increased tungsten release and impurity accumulation [C. Challis et al., Europhysics Conference Abstracts 41F, 2.153 (2017)]. The presented method relies mainly on the measurements collected by vacuum-ultra-violet and soft X-ray (SXR) diagnostics including the “SOXMOS” spectrometer and the SXR camera system. Both diagnostics have some limitations. Consequently, only a combination of measurements from these systems is able to provide comprehensive information about high-Z [e.g., tungsten (W)] and mid-Z [nickel (Ni), iron (Fe), copper (Cu), and molybdenum (Mo)] impurities for their further quantitative diagnosis. Moreover, thanks to the large number of the SXR lines of sight, determination of a 2D radiation profile was also possible. Additionally, the experimental results were compared with numerical modeling based on integrated simulations with COREDIV. Detailed analysis confirmed that during seeding experiments, higher tungsten release is observed, which was also found in the past. Additionally, it was noticed that besides W, the contribution of molybdenum to SXR radiation was greater, which can be explained by the place of its origin.This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under Grant Agreement No. 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. This scientific work was partly supported by the Polish Ministry of Science and Higher Education within the framework of the scientific financial resources in the years 2014-2018 allocated for the realization of the international co-financed project.Postprint (author's final draft

Magnetic properties of exactly solvable doubly decorated Ising-Heisenberg planar models

Applying the decoration-iteration procedure, we introduce a class of exactly solvable doubly decorated planar models consisting both of the Ising- and Heisenberg-type atoms. Exact solutions for the ground state, phase diagrams and basic physical quantities are derived and discussed. The detailed analysis of the relevant quantities suggests the existence of an interesting quantum antiferromagnetic phase in the system.Comment: 9 pages, 9 figures, submitted to Physical Review

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

Comparative analysis of HSM, HPC and conventional milling methods of high-silicon aluminium alloys

W artykule porównano wyniki obróbki wysokokrzemowych siluminów (stop EN AC-AlSi21CuNi) różnymi metodami frezowania. Stopy aluminium o zawartości Si > 12% charakteryzują się złą skrawalnością, ze wzglądu na zwiększone zużycie narzędzi. Jest to spowodowane oddziaływaniem na narzędzie wydzieleń krzemu, który działa ściernie na narzędzie. Ma to niekorzystny wpływ na proces skrawania, pogarsza jakość i dokładność wykonywanych elementów. Istotne jest więc, aby wybrać odpowiednie parametry oraz metodę obróbki.This article compares the results of machining high-silicon aluminium alloy (alloy EN AC-AlSi21CuNi) different methods of milling. Aluminium alloys with content Si > 12% have a poor machinability, with regard on increased tool wear. This is due to partial impact on the tool of silicon, which acts on the abrasive tool. This adversely affects the cutting process, compromises the quality and accuracy of performance parts. It is therefore important to select appropriate parameters and the method of machining

Comparative study of surface roughness of selected magnesium alloys after milling with carbide tool and PKD

W artykule przedstawiono: zastosowanie obróbki frezowaniem, właściwości wybranych stopów Mg, przykłady elementów lotniczych wykonywanych ze stopów Mg, problematykę obróbki oraz skrawalność stopów lekkich w oparciu o dane literaturowe oraz dotychczasowe badania, program oraz metodykę przeprowadzonych badań, podsumowanie, wnioski wynikające z przeprowadzonych badań oraz dane literaturowe.This article presents: milling application, properties of selected Mg alloys, examples of aviation elements made of Mg alloys, processing problems and machinability of light alloys based on literature data taken from literature sources and previous researches, program and methodology of the research, summary, conclusions and references