Influence of atomic and molecular gases on laser produced plasmas

Disertacija se bavi laserski proizvedenim plazmama te njihovom karakterizacijom posredstvom optičke emisijske i apsorpcijske spektroskopije. Ove plazme, prisutne u različitim područjima tehničkih i prirodnih znanosti, predstavljaju važan objekt istraživanja zbog mnogobrojnih primjena te neriješenih problema. Istraživanja opisana u ovoj disertaciji usmjerena su na nekoliko čimbenika koji utječu na nastanak plazme i procese koji se u njoj odvijaju. Proučavan je utjecaj vrste i tlaka pozadinskog plina, a koji utječu na kemiju i dinamiku širenja plazme, te energije lasera i sastava mete koji zajedno definiraju raspodjelu temperature unutar mete i njeno isparavanje. Osim eksperimentalnih mjerenja, radi potpunije analize načinjena je usporedba s teorijskim modelima. Dobiveni podaci mogu se upotrijebiti u području laserske depozicije te kemijske analize uzoraka.This dissertation deals with laser produced plasmas and their characterization by means of optical emission and absorption spectroscopy. These plasmas, today present in different areas of engineering and natural sciences, are interesting for the research due to their numerous applications as well as many open questions about their properties. Here, the research is focused towards the influence of several factors on the production of plasma. It was found that argon gas leads to stronger optical emission while the helium gas leads to more uniform plasma composition over larger pressure range together with lower ionization degree. Moreover, from absorption line shapes it can be concluded that surrounding excited gas motion is thermal, while motion of ablated atoms has preferential direction. Comparing different ablation targets, aluminium was found to give the highest yield of metastable helium. By comparing measured and simulated line shapes it was found that plasma expansion can be simulated using a simple model which takes into account only a few simple parameters. The ratio of forward and backward moving particles was measured to be ≈ 10%

DESIGN OF HYDRAULIC LOG GRAPPLE

Tema ovog rada bila je konstrukcija hidrauličkih škara za trupce. U radu je provedena kratka analiza sličnih postojećih rješenja dostupnih na tržištu, prema kojima je stvoren koncept. Za odabrani koncept proveden je proračun glavnih nosivih dijelova, odabrane su hidrauličke i ostale komponente, te konstruirani ostali potrebni dijelovi. Konačno rješenje je modelirano u CatiaV5 gdje je izvršena simulacija naprezanja te je izrađena tehnička dokumentacija.The topic of this thesis is design of hydraulic log grapple. The short analysis of similar products available on the market was used to make a concept. For the selected concept there was made a calculation of main load-bearing parts, selection of hydraulic components, and selection and design of other necessary parts. The final solution was designed in CatiaV5 which was used for making of stress analysis and for making of tehnical documentation

DESIGN OF HYDRAULIC LOG GRAPPLE

Tema ovog rada bila je konstrukcija hidrauličkih škara za trupce. U radu je provedena kratka analiza sličnih postojećih rješenja dostupnih na tržištu, prema kojima je stvoren koncept. Za odabrani koncept proveden je proračun glavnih nosivih dijelova, odabrane su hidrauličke i ostale komponente, te konstruirani ostali potrebni dijelovi. Konačno rješenje je modelirano u CatiaV5 gdje je izvršena simulacija naprezanja te je izrađena tehnička dokumentacija.The topic of this thesis is design of hydraulic log grapple. The short analysis of similar products available on the market was used to make a concept. For the selected concept there was made a calculation of main load-bearing parts, selection of hydraulic components, and selection and design of other necessary parts. The final solution was designed in CatiaV5 which was used for making of stress analysis and for making of tehnical documentation

Enhancement of optical emission signal in double-pulse laser ablation of titanium in vacuum

Laser plasma of Ti produced in vacuum was studied by optical emission spectroscopy. The plasma was produced in a single-pulse and a double-pulse mode of ablation in a collinear configuration of laser beams. It was shown that there is a significant enhancement in emission intensity in double-pulse mode. Moreover, depending on the delay time between laser pulses in double-pulse mode signal enhancement (up to 18-fold) was further optimized. Measurement of emission from neutral and ionized Ti atoms showed that there is an optimal delay time for which emission enhancement is maximal, for both ions and neutrals. It was shown that using double-pulse laser ablation the enhancement is mostly pronounced when emission from plasma near the target surface is taken into account. This increases the limit of detection and the signal/background ratio