High resolution spectroscopy of x-rays emission on ion microprobe

Na temelju dosadašnjeg iskustva u mjerenjima Kβ spektara 3d prijelaznih metala i njihovih spojeva na već postojećem visokorazlučivom spektrometru rendgenskoga zračenja Laboratorija za interakciju ionskih snopova konstruiran je umanjeni valno disperzivni sustav za rad s fokusiranim ionskim snopovima. Jedna od značajnijih prednosti novog spektrometra je njegova jednostavnost jer su meta i detektor na fiksnim položajima dok se promjena kuta difrakcije postiže linearnim pomakom ravnog kristala duţ osi paralalelne ionskom snopu. Kombinacija ionskog mikrosnopa te CCD detektora dobre prostorne rezolucije omogućila je smanjene dimenzija u odnosu na prijašnje valno disperzivne sustave, čime se je povećala efikasnost sustava, a uz zadržavanje energijskog razlučivanja pogodnog za mjerenja fine strukture rendgenskoga zračenja na mikrometarskim uzorcima. U radu su opisane sve faze izrade spektrometra koje su uključivale optimizaciju geometrije sustava pomoću XTRACE programa te dizajn vakuumske komore u kojoj su smješteni nosač za mete, ravni kristal i detektor. Napravljena je procedura za obradu signala koja dvodimenzionalne slike snimljenog zračenja preoblikuje u visokorazlučive spektre. Novim spektrometrom se proučavao utjecaj kemijskih efekata na karakteristično rendgensko Kα i Kβ zračenje silicija, sumpora i njihovih spojeva pobudom protonima. Utjecaj višestruke ionizacije na finu strukturu karakterističnoga rendgenskoga zračenja je proučavan pobudom ionima ugljika. Ispitane su i mogućnosti spektrometra u razlikovanju spojeva sulfata od sulfida bazirane na kemijskim efektima u Kβ spektrima sumpora te mogućnosti razdvajanja K i M linija rendgenskoga zračenja koje nije moguće razlučiti energijsko disperzivnim detektorima.Downsized high resolution wavelength dispersive x-ray spectrometer was constructed for work with focused beams on ion microprobe. The experience gained in using the present large spectrometer designed for broad beams to measure Kβ spectra of 3d transition metals' and their compounds in the Laboratory for ion beam interactions was taken in account. Important advantage of the new spectrometer is in its simplicity: both target and the detector are mounted on fixed positions while the change of diffraction angle is achieved by linear displacement of the flat diffraction crystal along the axis parallel to the ion beam direction. Downsizing was achieved by combining ion microbeam and CCD detector of good spatial resolution, which together with reasonably good energy resolution enables measurement of the fine structure in x-ray spectra on microscopic samples. All steps of the spectrometer’s development are described and they include geometry optimisation with XTRACE simulations and design of the vacuum chamber which encloses sample holder, crystal and detector. Algorithms for transferring two-dimensional images of the radiation collected with the position sensitive detector to x-ray energy spectra is developed. Spectrometer was used to test influence of chemical effects on characteristic Kα and Kβ x-ray emission of silicon, sulphur and their compounds induced by protons. Multiple ionization and its consequences on characteristic x-ray emission of sulphur were measured with carbon ions. Spectrometer's capabilities to distinguish sulphate and sulphide compounds based on chemical effects in sulphur Kβ spectra induced with protons are demonstrated. Also possibilities to resolve K and M lines that overlap in energy dispersive spectra are shown

Monitoring ion track formation using in situ RBS/c and ERDA

The aim of this work is to investigate feasibility of the ion beam analysis techniques for monitoring swift heavy ion track formation. First, use of the in situ Rutherford backscattering spectroscopy in channeling mode to observe damage build-up in quartz SiO2 after MeV heavy ion irradiation is demonstrated. Second, new results of the in situ grazing incidence time-of-flight elastic recoil detection analysis used for monitoring the surface elemental composition during ion tracks formation in various materials are presented. Ion tracks were found on SrTiO3, quartz SiO2, a-SiO2 and muscovite mica surfaces by atomic force microscopy, but in contrast to our previous studies on GaN and TiO2, surface stoichiometry remained unchanged

Dust Monitors in JET with ITER-like Wall for Diagnosis of Mobilized Particles and Co-Deposited Layers

Silicon plates were installed above the inner and outer divertor of the JET with the ITER-like wall (ILW) after the second and third ILW campaigns to monitor dust generation and deposition with the aim to determine the morphology and content of individual particles and co-deposits, including deuterium content. Particular interest was in metal-based particles: Be, W, steel, Cu. Ex-situ examination after two ILW campaigns was performed by a set of microscopy and ion beam methods including micro-beam nuclear reaction analysis and particle-induced X-ray emission. Different categories of Be-rich particles were found: co-deposits peeled-off from plasma-facing components (PFC), complex multi-element spherical objects, and solid metal splashes and regular spherical droplets. The fuel content on the two latter categories was at the level of 1 × 1016 at/cm−2 indicating that Be melting and splashing occurred in the very last phase of the second experimental campaign. The splashes adhere firmly to the substrate thus not posing risk of Be dust mobilisation. No tungsten droplets were detected. The only W-containing particles were fragments of tungsten coatings from the divertor tiles