| 1. |
- Grigore, E., et al.
(författare)
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Helium depth profile measurements within tungsten coatings by using Glow Discharge Optical Emission Spectrometry (GDOES)
- 2019
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Ingår i: Surface & Coatings Technology. - : ELSEVIER SCIENCE SA. - 0257-8972 .- 1879-3347. ; 376, s. 21-24
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Tidskriftsartikel (refereegranskat)abstract
- In the present paper results concerning the implementation of the Glow Discharge Optical Emission Spectrometry (GDOES) for measure the He depth profile within W coatings are given. The He emission line situated at 587.5 nm was used in this respect. W coating containing He up 10 at.% and with thickness of 5 pm have been obtained by Combined Magnetron Sputtering and Ion Implantation (CMSII) method. The coatings structure and morphology was investigated using Scanning Electron Microscopy (SEM) measurements. The He retention within the coatings was evaluated by using Thermal Desorption Spectroscopy (TDS). Time-of-Flight Elastic Recoil Detection Analysis (TOF ERDA) measurements has been used to determine chemical composition of the coatings. Results of TOF-ERDA measurements results were used to calibrate the GDOES equipment. Using these data the GDOES depth profiles of the He within W coatings have been obtained.
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| 2. |
- Hakola, A., et al.
(författare)
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Plasma-wall interaction studies in the full-W ASDEX upgrade during helium plasma discharges
- 2017
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Ingår i: Nuclear Fusion. - : IOP PUBLISHING LTD. - 0029-5515 .- 1741-4326. ; 57:6
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Tidskriftsartikel (refereegranskat)abstract
- Plasma-wall interactions have been studied in the full-W ASDEX Upgrade during its dedicated helium campaign. Relatively clean plasmas with a He content of > 80% could be obtained by applying ion cyclotron wall conditioning (ICWC) discharges upon changeover from D to He. However, co-deposited layers with significant amounts of He and D were measured on W samples exposed to ICWC plasmas at the low-field side (outer) midplane. This is a sign of local migration and accumulation of materials and residual fuel in regions shadowed from direct plasma exposure albeit globally D was removed from the vessel. When exposing W samples to ELMy H-mode helium plasmas in the outer strike-point region, no net erosion was observed but the surfaces had been covered with co-deposited layers mainly consisting of W, B, C, and D and being the thickest on rough and modified surfaces. This is different from the typical erosion-deposition patterns in D plasmas, where usually sharp net-erosion peaks surrounded by prominent net-deposition maxima for W are observed close to the strike point. Moreover, no clear signs of W nanostructure growth or destruction could be seen. The growth of deposited layers may impact the operation of future fusion reactors and is attributed to strong sources in the main chamber that under suitable conditions may switch the balance from net erosion into net deposition, even close to the strike points. In addition, the absence of noticeable chemical erosion in helium plasmas may have affected the thickness of the deposited layers. Retention of He, for its part, remained small and uniform throughout the strike-point region although our results indicate that samples with smooth surfaces can contain an order of magnitude less He than their rough counterparts.
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| 3. |
- Kokkoris, M., et al.
(författare)
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Benchmarking the evaluated proton differential cross sections suitable for the EBS analysis of natSi and 16O
- 2017
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Ingår i: Nuclear Instruments and Methods in Physics Research Section B. - : Elsevier BV. - 0168-583X .- 1872-9584. ; 405, s. 50-60
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Tidskriftsartikel (refereegranskat)abstract
- The evaluated proton differential cross sections suitable for the Elastic Backscattering Spectroscopy (EBS) analysis of Si-nat and O-16, as obtained from SigmaCalc 2.0, have been benchmarked over a wide energy and angular range at two different accelerator laboratories, namely at N.C.S.R. 'Demokritos', Athens, Greece and at Ruder Boskovic Institute (RBI), Zagreb, Croatia, using a variety of high-purity thick targets of known stoichiometry. The results are presented in graphical and tabular forms, while the observed discrepancies, as well as, the limits in accuracy of the benchmarking procedure, along with target related effects, are thoroughly discussed and analysed. In the case of oxygen the agreement between simulated and experimental spectra was generally good, while for silicon serious discrepancies were observed above E-p,E-lab = 2.5 MeV, suggesting that a further tuning of the appropriate nuclear model parameters in the evaluated differential cross-section datasets is required.
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