An analytical expression for ion velocities at the wall including the sheath electric field and surface biasing for erosion modeling at JET ILW

For simulation of plasma-facing component erosion in fusion experiments, an analytical expression for the ion velocity just before the surface impact including the local electric field and an optional surface biasing effect is suggested. Energy and angular impact distributions and the resulting effective sputtering yields were produced for several experimental scenarios at JET ILW mostly involving PFCs exposed to an oblique magnetic field. The analytic solution has been applied as an improvement to earlier ERO mod- elling of localized, Be outer limiter, RF-enhanced erosion, modulated by toggling of a remote, however magnetically connected ICRH antenna. The effective W sputtering yields due to D and Be ion impact in Type-I and Type-III ELMs and inter-ELM conditions were also estimated using the analytical approach and benchmarked by spectroscopy. The intra-ELM W sputtering flux increases almost 10 times in comparison to the inter-ELM flux.EURATOM 63305

Effect of metformin on transcriptome and adipokinome of adipocytes of local fat deposts of patients with ischemic heart disease

BACKGROUND: The information available to date on the effect of metformin on the transcriptome and secretory capacity of adipocytes in human adipose tissue (AT) is scarce and contradictory. The study analyzed whether metformin in vitro modulates gene expression and secretion of adiponectin and leptin in the AT of subcutaneous (SAT), epicardial (EAT) and perivascular (PVAT) localization of patients with ischemic artery disease (IHD).AIM: To assess the effect of metformin at various concentrations (1 and 10 mmol / L) on the level of expression of adiponectin and leptin genes and their content in adipocytes of subcutaneous, epicardial and perivascular AT of patients with IHD.MATERIALS AND METHODS: The study included 134 patients with IHD and indications for direct myocardial revascularization by coronary artery bypass grafting (CABG). During the operation, biopsies of SAT, EAT and PVAT were obtained for 3–5 gram, which served as a source of adipocytes. Isolated adipocytes were cultured for 24 hours with and without metformin (1 and 10 mmol / L). After a day of incubation, the expression of the ADIPOQ and LEP genes and the level of secretion of adiponectin and leptin in the culture medium of adipocytes were determined. Statistical processing was performed using the GraphPad Prism 6 software package (GraphPad Software, La Jolla, CA, USA) and Statistica software, 6.1 (Dell Software, Inc., Round Rock, TX, USA).RESULTS: The adipocytes of the EAT and PVAT of patients with IHD were characterized by an imbalance in the adipokine system, manifested by a low level of ADIPOQ expression and a high LEP expression in comparison with adipocytes of the SAT. Metformin increased the level of ADIPOQ expression and its secretion by adipocytes regardless of their location, while a low concentration (1 mmol / L) in adipocytes of EAT had a stronger effect compared to 10 mmol / L. Metformin had a multidirectional effect on the level of leptin in adipocytes, which depended on their localization: both in low (1 mmol / L) and high concentrations (10 mmol / L), the drug reduced the level of LEP expression and protein secretion in the culture medium of adipocytes of the SAT. EAT had no significant effect on adipocytes. In PVAT, metformin increased the expression and secretion of leptin regardless of concentration.CONCLUSION: Metformin has a direct effect on adipocytes in SAT, EAT, and PVAT and is able to modulate their activity, which is a promising strategy for maintaining the balance of adipokines in AT, especially epicardial and perivascular localization

CYTOKINE PROFILE IN VISCERAL OBESITY AND ADVERSE CARDIOVASCULAR PROGNOSIS OF MYOCARDIAL INFARCTION

Presence of myocardial infarction in patients with obesity can lead to an uncontrolled increase in proinflammatory cytokines and unfavorable course of the pathological process. Objective: to study the relationship of key inflammatory factors and the development of complications at different terms after myocardial infarction in patients with visceral obesity. The study involved 94 men with myocardial infarction. Visceral obesity was diagnosed by multi-slice computed tomography (LightspeedVCT 64 ,General Electric,USA). On the 1st and 12th day of hospitalization, we determined serum concentrations of interleukins (TNFα, IL-1β, IL-6, IL-8 IL-10 and IL-12), and C-reactive protein. Adverse cardiovascular events were documented during the next year. The most informative indicators were identified by a stepwise logistic regression analysis. In patients with myocardial infarction an imbalance of cytokine profile revealed, i.e., an increase in proinflammatory markers (TNFα, IL-1β, IL-6, IL-8, IL-12, CRP), along with decrease in IL-10, being more pronounced in cases of visceral obesity. Among the studied markers, closest relationship was observed between visceral obesity and serum concentrations of IL-6 and CRP. Over the year, adverse cardiovascular events proved to be more frequent in patients with visceral obesity. Post-infarction complication risk was associated with higher concentrations of IL-6, IL-12 and IL-10 deficiency. Hence, development of adverse cardiovascular events within a year after myocardial infarction is more typical to the patients with visceral obesity, and is accompanied by activation of proinflammatory cytokines and IL-10 deficiency

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

Determination of tungsten sources in the JET-ILW divertor by spectroscopic imaging in the presence of a strong plasma continuum

The identification of the sources of atomic tungsten and the measurement of their radiation distribution in front of all plasma-facing components has been performed in JET with the help of two digital cameras with the same two-dimensional view, equipped with interference filters of different bandwidths centred on theW I (400.88 nm) emission line. A new algorithm for the subtraction of the continuum radiation was successfully developed and is now used to evaluate the W erosion even in the inner divertor region where the strong recombination emission is dominating over the tungsten emission. Analysis of W sputtering and W redistribution in the divertor by video imaging spectroscopy with high spatial resolution for three different magnetic configurations was performed. A strong variation of the emission of the neutral tungsten in toroidal direction and corresponding W erosion has been observed. It correlates strongly with the wetted area with a maximal W erosion at the edge of the divertor tile

The effect of beryllium oxide on retention in JET ITER-like wall tiles

Preliminary results investigating the microstructure, bonding and effect of beryllium oxide formation on retention in the JET ITER-like wall beryllium tiles, are presented. The tiles have been investigated by several techniques: Scanning Electron Microscopy (SEM) equipped with Energy Dispersive X-ray (EDX), Transmission Electron microscopy (TEM) equipped with EDX and Electron Energy Loss Spectroscopy (EELS), Raman Spectroscopy and Thermal Desorption Spectroscopy (TDS). This paper focuses on results from melted materials of the dump plate tiles in JET. From our results and the literature, it is concluded, beryllium can form micron deep oxide islands contrary to the nanometric oxides predicted under vacuum conditions. The deepest oxides analyzed were up to 2-micron thicknesses. The beryllium Deuteroxide (BeOxDy) bond was found with Raman Spectroscopy. Application of EELS confirmed the oxide presence and stoichiometry. Literature suggests these oxides form at temperatures greater than 700 °C where self-diffusion of beryllium ions through the surface oxide layer can occur. Further oxidation is made possible between oxygen plasma impurities and the beryllium ions now present at the wall surface. Under Ultra High Vacuum (UHV) nanometric Beryllium oxide layers are formed and passivate at room temperature. After continual cyclic heating (to the point of melt formation) in the presence of oxygen impurities from the plasma, oxide growth to the levels seen experimentally (approximately two microns) is proposed. This retention mechanism is not considered to contribute dramatically to overall retention in JET, due to low levels of melt formation. However, this mechanism, thought the result of operation environment and melt formation, could be of wider concern to ITER, dependent on wall temperatures

Improved ERO modelling of beryllium erosion at ITER upper first wall panel using JET-ILW and PISCES-B experience

ERO is a 3D Monte-Carlo impurity transport and plasma-surface interaction code. In 2011 it was applied for the ITER first wall (FW) life time predictions [1] (critical blanket module BM11). After that the same code was significantly improved during its application to existing fusion-relevant plasma devices: the tokamak JET equipped with an ITER-like wall and linear plasma device PISCES-B. This has allowed testing the sputtering data for beryllium (Be) and showing that the “ERO-min” fit based on the large (50%) deuterium (D) surface content is well suitable for plasma-wetted areas (D plasma). The improved procedure for calculating of the effective sputtering yields for each location along the plasma-facing surface using the recently developed semi-analytical sheath approach was validated. The re-evaluation of the effective yields for BM11 following the similar revisit of the JET data has indicated significant increase of erosion and motivated the current re-visit of ERO simulations

Beryllium global erosion and deposition at JET-ILW simulated with ERO2.0

The recently developed Monte-Carlo code ERO2.0 is applied to the modelling of limited and diverted discharges at JET with the ITER-like wall (ILW). The global beryllium (Be) erosion and deposition is simulated and compared to experimental results from passive spectroscopy. For the limiter configuration, it is demonstrated that Be self-sputtering is an important contributor (at least 35%) to the Be erosion. Taking this contribution into account, the ERO2.0 modelling confirms previous evidence that high deuterium (D) surface concentrations of up to ∼50% atomic fraction provide a reasonable estimate of Be erosion in plasma-wetted areas. For the divertor configuration, it is shown that drifts can have a high impact on the scrape-off layer plasma flows, which in turn affect global Be transport by entrainment and lead to increased migration into the inner divertor. The modelling of the effective erosion yield for different operational phases (ohmic, L- and H-mode) agrees with experimental values within a factor of two, and confirms that the effective erosion yield decreases with increasing heating power and confinement

Modelling of tungsten erosion and deposition in the divertor of JET-ILW in comparison to experimental findings

The erosion, transport and deposition of tungsten in the outer divertor of JET-ILW has been studied for an HMode discharge with low frequency ELMs. For this specific case with an inter-ELM electron temperature at the strike point of about 20 eV, tungsten sputtering between ELMs is almost exclusively due to beryllium impurity and self-sputtering. However, during ELMs tungsten sputtering due to deuterium becomes important and even dominates. The amount of simulated local deposition of tungsten relative to the amount of sputtered tungsten in between ELMs is very high and reaches values of 99% for an electron density of 5E13 cm$^{-3}$ at the strike point and electron temperatures between 10 and 30 eV. Smaller deposition values are simulated with reduced electron density. The direction of the B-field significantly influences the local deposition and leads to a reduction if the E×B drift directs towards the scrape-off-layer. Also, the thermal force can reduce the tungsten deposition, however, an ion temperature gradient of about 0.1 eV/mm or larger is needed for a significant effect. The tungsten deposition simulated during ELMs reaches values of about 98% assuming ELM parameters according to free-streaming model. The measured WI emission profiles in between and within ELMs have been reproduced by the simulation. The contribution to the overall net tungsten erosion during ELMs is about 5 times larger than the one in between ELMs for the studied case. However, this is due to the rather low electron temperature in between ELMs, which leads to deuterium impact energies below the sputtering threshold for tungsten

First mirror test in JET for ITER: Complete overview after three ILW campaigns

The First Mirror Test for ITER has been carried out in JET with mirrors exposed during: (i) the third ILW campaign (ILW-3, 2015–2016, 23.33 h plasma) and (ii) all three campaigns, i.e. ILW-1 to ILW-3: 2011–2016, 63,52 h in total. All mirrors from main chamber wall show no significant changes of the total reflectivity from the initial value and the diffuse reflectivity does not exceed 3% in the spectral range above 500 nm. The modified layer on surface has very small amount of impurities such as D, Be, C, N, O and Ni. All mirrors from the divertor (inner, outer, base under the bulk W tile) lost reflectivity by 20–80% due to the beryllium-rich deposition also containing D, C, N, O, Ni and W. In the inner divertor N reaches 5×10$^{17}$ cm$^{-2}$, W is up to 4.3×10$^{17}$ cm$^{-2}$, while the content of Ni is the greatest in the outer divertor: 3.8×10$^{17}$ cm$^{-2}$. Oxygen-18 used as the tracer in experiments at the end of ILW-3 has been detected at the level of 1.1×10$^{16}$ cm$^{-2}$. The thickness of deposited layer is in the range of 90 nm to 900 nm. The layer growth rate in the base (2.7 pm s$^{-1}$) and inner divertor is proportional to the exposure time when a single campaign and all three are compared. In a few cases, on mirrors located at the cassette mouth, flaking of deposits and erosion occurred