Data on erosion and hydrogen fuel retention in Beryllium plasma-facing materials

ITER will use beryllium as a plasma-facing material in the main chamber, covering a total surface area of about 620 m(2). Given the importance of beryllium erosion and co-deposition for tritium retention in ITER, significant efforts have been made to understand the behaviour of beryllium under fusion-relevant conditions with high particle and heat loads. This paper provides a comprehensive report on the state of knowledge of beryllium behaviour under fusion-relevant conditions: the erosion mechanisms and their consequences, beryllium migration in JET, fuel retention and dust generation. The paper reviews basic laboratory studies, advanced computer simulations and experience from laboratory plasma experiments in linear simulators of plasma-wall interactions and in controlled fusion devices using beryllium plasma-facing components. A critical assessment of analytical methods and simulation codes used in beryllium studies is given. The overall objective is to review the existing set of data with a broad literature survey and to identify gaps and research needs to broaden the database for ITER.Peer reviewe

Overview of co-deposition and fuel inventory in castellated divertor structures at JET

The main focus of this work is fuel retention in plasma components of the JET water-cooled Mk-I divertors operated with small tiles, first with carbon fibre composite (CFC) and then with castellated beryllium. Until recently these have been the only large-scale structures of this type used in fusion experiments. Three issues regarding fuel retention and material migration are addressed: (i) accumulation in gaps separating tiles and in the grooves of castellation; (ii) comparison of deposition on carbon and beryllium; (iii) in-depth migration of deuterium into the bulk of CFC. The essential results are summarised as follows: (i) co-deposition occurs up to a few cm deep in the gaps between the Mk-I tiles; (ii) fuel inventory in the CFC tile gaps exceeds that on plasma-facing surfaces by up to a factor of 2; (iii) in gaps between the beryllium tiles from the inner divertor corner the fuel content reaches 30% of that on plasma-facing surfaces, whereas in the grooves of castellation in Be the fuel content is less than 3.0% of that found on the top surface; (iv) fuel inventory on the Be tiles is strongly associated with the carbon co-deposition; (v) the D content measured in the bulk (1.5 mm below the surface) on cleaved CFC tiles exceeds 1 x 10(15) cm(-2). Implications of these results for a next-step device are addressed and the transport mechanism into the gaps is briefly discussed. The results presented here suggest that in a machine with non-carbon walls in the main chamber (as foreseen for ITER) the material transport and subsequent fuel inventory in the castellation would be reduced.QC 2010111

Epigeic dune arthropods as indicator fortrampling intensity

Attīstoties Jūrmalas pilsētai un pieaugot antropogēnajai slodzei priekškāpu biotopos, tika izvēlēts veikt pētījumu par izmīdīšanas intensitātes ietekmi uz kāpās dzīvojošo posmkāju sabiedrībām. Pētījuma mērķis ir noskaidrot vai pastāv korelācija starp posmkāju kvantitatīvajiem rādītājiem, sugu daudzveidību un izmīdīšanas intensitāti, kā arī vai posmkāji var kalpot par indikatoru izmīdīšanas intensitātei priekškāpās. Pētījuma rezultāti parāda, ka mitrenes (Oniscoidea) un zirnekļi (Aranei) uzrādīja būtiskas sadalījuma atšķirības starp kontroles un ietekmes nogabaliem, kuros veikts pētījums, tāpēc šie taksoni labi indicē izmīdīšanu konkrētajā biotopā, arī Šenona sugu daudzveidības indekss konkrētajā biotopā ir labs rādītājs izmīdīšanas intensitātei, jo būtiski atšķiras starp kontroles un ietekmes nogabaliem. Formica cinerea izceļas kā laba indikatorsuga izmīdīšanas intensitātei, jo suga bija bieži satopama kontroles nogabalā, bet ietekmes nogabalā netika konstatēta nemaz. Atslēgas vārdi: priekškāpas, kāpu posmkāji, epigeiskie posmkāji, Formica cinerea, kāpu ekosistēmas, izmīdīšana, parauglaukumu metode.With the development of city Jurmala anthropogenic pressure on foredune habitants has increased. Therefore, research studies how trampling effects influence local arthropod communities. The study aims to investigate whether there is correlation between the amount of arthropods, biodiversity of arthropods and trampling intensity, as well as whether arthropods can be used as an indicator for trampling intensity in foredunes. The research results present that the woodlouse (Oniscoidae) and spiders (Aranei) showed significant distribution differences between control and impact area in which study was conveyed. These taxa well indicated trampling effects in particular habitat. Shannon biodiversity index also represented itself as reasonable criteria for indicating trampling effects, as it showed significant differences between control and impact area. Formica cinera stands out as a good indicator species due to its frequent occurrence in control areas plots and fact that it did not occur in any of impact areas plots. Key words: foredune, dune arthropods, epigeic arthropods, Formica cinerea, dune ecosystems, trampling, plots method

Deposition results from rotating collector diagnostics in JET

Rotating collectors (RC) were installed in JET during the period 2005-2007, each providing a time-resolved deposition pattern on the surface of a rotating silicon disc, which could be analysed once retrieved from the vessel. This paper reports results from the silicon disc removed from the RC located under the load-bearing septum replacement plate in JET in 2007. Nuclear reaction analysis results of the deposits on the disc have been correlated directly with the pattern of erosion and deposition observed by the quartz microbalance (QMB) located in an equivalent position. The thickest film in the time-resolved region (i.e. deposited in similar to 60 pulses) was similar to 250 nm, and the Be/C ratio was generally found to be 0.1 or lower, with two regions where the ratio rose to 0.2. The deposition observed with the QMB appears to be about a factor of four less.QC 2010111

Representation of Time in Shakespeare Sonnets

Bakalaura darbs ir veltīts laika prezentācijai Šekspīra sonetos. Šī darbā pirmā daļā ir apspriesta laika problēma cilvēku dzīvē. Ir norādīts, ka laiks – ir viens no cilvēku pieredzes fundamentālajiem raksturojumiem, bet laika sapratnes problēma un viņa atspoguļošana mākslā un literatūrā ir ļoti nopietna. Laika koncepts pastāvīgi mainās: no antīkās pasaules caur viduslaikiem un Renesansi līdz šim laikam. Laika problēma tika apspriesta laiku garumā no teoloģiska viedokļa, filosofijas viedokļa, metafiziska viedokļa, pētniecības un poētiska viedokļa. Laika tipiskais attēls Renesanse laikmetā bija iznīcinātāja attēls. Darba analitiskajā daļā tika apspriesta vieta, kuru laiks aizņēm Viljama Šekspira sonetos, kā arī lingvistiskie un stilistiskie paņēmieni, kurus Šekspirs izmantoja laika attēlojumam savos sonetos. Viljama Šekspira sonetos laiks ir personificēts. Ar tādu paņēmienu palīdzību, kā sonetas formas nozīmes specifiskā organizācija, jautājumi un atbildes, kontrasts, tiešais uzsaukums laikam, vietniekvārdi „tu”, „tev”, „tavs”, pavēles izteiksme, specifiskie darbības vārdi, vārda „Laiks” uzrakstīšana no sākumburtas, kā arī metaforas, metonīmija un sinekdoha salīdzināšana, epiteti un hiperbolas, dzejnieks stāda laiku priekšā, kā cietsirdīgo un valdonīgo cilvēku, kurš ir nežēlīgs cilvēcei, mīlestībai un skaistumam. Izmantojot šos lingvistiskus un stilistiskus paņēmienus, dzejnieks rada emocionālo un izteiksmīgu laika skatu un demonstrē savu attieksmi pret laiku un viņa lomu pasaulē. Laika attēls Šekspira sonetos ir ļoti spožs un unikāls. Dižs dzejnieks uzrāda laiku par iznīcinātāju ar savu pašu māksliniecisko paņēmienu un piedāvā savu pašu ceļu, kā ar to cīnīties.The bachelor paper is devoted to the presentation of time in Shakespeare's sonnets. In the first part of this work the time problem in humans’ life has been discussed. It has been shown that time is one of the most fundamental characteristics of human experience, and the problem of time understanding and reflecting in art and literature is an important one. The concept of time has been constantly changing from the Antiquity through the Middle Age and Renaissance to the present day. The problem of time has been discussed from theological, philosophical, metaphysical, scientific and poetical point of view throughout the centuries. The typical Renaissance image of time was as a destroyer. In the analytical part of the work the place of time in the Sonnets by William Shakespeare has been to be discussed, as well as linguistic and stylistic devices used by Shakespeare to represent time in his sonnets. It has been shown that the main specificity of time described in the sonnets by William Shakespeare is that time is personified. By means of such devices as the specific meaning organization of the sonnet form, questions and answers, contrasting, direct addressing time, use of pronouns thou, thee, thy, imperative mood, action verbs, capitalization of the word “Time”, as well as such tropes as metaphors, similes, metonymy, synecdoche, epithets and hyperboles the poet represents time as a cruel and powerful person, pitiless to the humankind, love and beauty. Using these linguistic and stylistic devices the poet creates an emotional and expressive picture of time and shows his own attitude towards time and its role in the world. The image of time in Shakespeare’s sonnets is very bright and unique as the great poet represents the time destroyer in his own artistic way and suggests his own ways to fight it

Examining the links between CSR and IHRM strategy : a comparative study of the UK AND Korea

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

First Mirrors Test in JET for ITER : An overview of optical performance and surface morphology

Metallic mirrors will be essential components of all optical systems for plasma diagnosis in ITER. A comprehensive First Mirror Test (FMT) has been carried out in the JET tokamak. The exposure was followed by a characterisation of mirrors and their carriers. The main results obtained by optical and surface analysis methods are: (i) reflectivity of all tested mirrors is degraded either by erosion with charge exchange neutrals or by the formation of thick deposits; (ii) deuterium and carbon are the main elements detected on all mirror surfaces and the presence of beryllium is also found in several cases; (iii) thick deposits show columnar structure; (iv) bubble-like structures are detected in deposits; their formation is a probable reason for deposits' disintegration and peeling-off; (v) the deposition in channels in the divertor cassettes is pronounced at the very entrance and then it sharply decreases with the distance from the plasma, lambda similar to 5-7 mm.QC 2010122

Retention of noble and rare isotope gases in plasma-facing components-Experience from the JET tokamak with the ITER-like wall

Plasma edge cooling, ion cyclotron wall conditioning and disruption mitigation techniques involve massive gas injection (by puffs or pellets) to the torus. A certain fraction remains in plasma-facing components (PFC) due to co-deposition and implantation. An uncontrolled release/desorption of such retained species affects the stability of plasma operation. The aim of this work was to determine the lateral and depth distribution of noble (3He, 4He, Ne, Ar), seeded (N2, Ne, Ar) and tracer gases (15N, 18O) in PFC retrieved from the JET tokamak with the ITER-Like Wall (JET-ILW) after three experimental campaigns (ILW-1, ILW-2, ILW-3). Results regarding the retention of those gases are shown as well as a comparison to the deuterium retention in the studied areas. Heavy ion elastic recoil detection analysis was used, being the only technique capable of detection and quantitative assessment of all elements, especially low-Z isotopes. Helium was found on the divertor Tile 5, locally up to 44.1015 3He cm-2 and 12.1015 4He cm-2, and on the limiters as well. Neon was found in two positions on the limiters, with up to 10.1015 Ne cm-2 and the 15N tracer on Be limiters exposed to ILW-3. A correlation of N retention with the N seeding rates for each campaign has also been found

Spatial and landscape structure changes of town Saldus during 20-21 century

Bakalaura darbā tiek pētīta Saldus pilsētas publiskā ārtelpas pieejamība un piemērotība iedzīvotājiem, vietas identitāte, mazpilsētas vides elementi, pilsētas „mezglu punkti”, dizains un ainavas mainība no 20. gadsimta sākuma līdz 21. gadsimta sākumam. Darba mērķis ir raksturot Saldus pilsētvides un telpiskās struktūras veidošanos un izvērtēt ainaviski nozīmīgās „mezgla” vietas pilsētā. Izstrādāt priekšlikumus pilsētvides dizaina pilnveidei. Darbs kopumā izklāstīts 54 lappusēs. Tajā iekļauts 21 attēls. Darbā izmantots 41 literatūras avots un pievienoti 24 pielikumi. Raksturvārdi: pilsētas ainavas mainība; telpiskā struktūra; vietas identitāteIn Bachelor’s paper study is the spatial and landscape structure of town Saldus, its accesibility for inhabitants, place identity, elements of provincial town environment, nodes, design and changes of landscape from the begining of 20th century back to nowadays – begining of 21st century. The aim of this reserch is to describe spatial structure development and to evaluate important lanscape nodes in provincial town of Saldus. To draw up a system of suggestions for design of town Saldus. This reaserch consists of 54 pages, that includes 21 picture. Also there are 41 bibliographic sources and added 24 appendixes. Key words: townscape fluctuation; spatial structure; place identit

An overview of a comprehensive First Mirror Test for ITER at JET

The test was performed with 32 stainless steel and molybdenum mirrors placed in pan-pipe shaped cassettes and exposed in JET in the divertor and on the main chamber wall for 127000 s including 97000 s of X-point operation. Surface composition and total reflectivity were determined afterwards All mirrors. from the divertor were coated with deuterated carbon deposits causing the reflectivity loss by a factor of 6-10 in the visible range. Flaking and exfoliation of deposits were observed in some cases On the main. chamber wall the deposition occurred mainly on mirrors located deep in cassette channels whereas mirrors close to the channels entrances were free from deposits and retained fair reflectivity (similar to 90% of initial value) especially in the infra-red range. No significant differences in behaviour of steel and molybdenum were noted. The need for development of methods for mirror cleaning and/or protection in a reactor-class device is addressed.QC 2010111