25 KB304 KB22 KB200020242011Drenik, AleksanderEleršič, KristinaModic, MartinaPanjan, Peterštevilka:3letnik:45str. 281-285ISSN:1580-2949COBISSID:861610URN:URN:NBN:SI:doc-VGDJLLVIenInštitut za kovinske materiale in tehnologijeMateriali in tehnologijeamorfni ogljikkisikplazmarekombinacijaProbability of recombination and oxidation of O atoms on a-C:H| Verjetnost za rekombinacijo in oksidacijo za atome kisika na površini a-C:H|In the search for a sustainable energy source for future generations, thermonuclear fusion should not be left unconsidered. One of the important problems of current and near-future fusion devices is the formation of amorphous hydrogenated carbon deposits (a-C:H), which have to be removed regularly. Removal of a-C:H by atomic oxygen seems like a suitable candidate for a cleaning method. Efficiency of the cleaning method will depend on the efficiency of atomic oxygen delivery. This in turn will depend on the atom loss on reactor walls, which is predominantly governed by recombination. An experiment was performed to measure the recombination coefficient of a-C:H for neutral oxygen atoms. The source of atomic oxygen was an inductively coupled RF discharge, created in pure oxygen. The oxygen densities were measured by a nickel tipped FOCP. The a-C:H sample was prepared by thermionic arc sputtering of a graphite target in a mixed argon / acetylene atmosphere. The recombination coefficient was found to be of the order of 10-3. Moreover, it was discovered that the a-C:H deposition was eroded by O atoms during the experiment. In a rough estimate, the probability of oxidation was found to be two orders of magnitude lower than the probability of recombinationPri iskanju trajnostnega energijskega vira za prihodnje generacije ne smemo prezreti termonuklearne fuzije. Ena od najpomembnejših težav sodobnih in prihodnjih fuzijskih naprav je nalaganje amorfnih hidrogeniziranih ogljikovih nanosov (a-C:H), ki jih je treba redno odstranjevati. Primeren kandidat za metodo čiščenja se ponuja odstranjevanje a-C:H z atomskim kisikom. Učinkovitost te metode bo odvisna od učinkovitosti dotoka atomskega kisika k površini. Ta pa bo odvisna od izgub atomov na stenah rekatorja, v katerih je največji delež rekombinacija. Izvedli smo eksperiment z namenom izmeriti rekombinacijski koeficient a-C:H za nevtralne kisikove atome. Vir atomskega kisika je bila induktivno sklopljena RF-razelektritev v čistem kisiku. Gostote atomskega kisika smo merili z nikljevo optično katalitično sondo. Vzorec a-C:H je bil pripravljen z razprševanjem grafitne tarče v atmosferi mešanice argona in acetilena s termionskim oblokom. Ugotovili smo, da je rekombinacijski koeficient reda velikosti 10-3. Nadalje smo ugotovili, da je med eksperimentom nastala erozija a-C:H-vzorca zaradi delovanja O-atomov. Z grobo oceno smo ugotovili, da je verjetnost za oksidacijo dva velikostna reda nižja od verjetnosti za rekombinacijoTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije