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Ova doktorska disertacija sadrži dve celine. U prvoj celini su proučavani transportni koefi- cijenti trećeg reda za rojeve naelektrisanih čestica u gasovima. Struktura transportnog tenzora trećeg reda u svim konfiguracijama električnog i magnetskog polja određena je primenom metoda grupnih projektora. Fizička interpretacija individualnih komponenti ovog tenzora je analizirana na osnovu fluks gradijentne relacije i generalisane difuzione jednačine. Zavisnost transportnih koeficijenata trećeg reda od redukovanog električnog polja i njihova osetljivost na elementarne sudarne procese ispitane su za veliki broj modelnih i realnih gasova u Monte Carlo simulacijama i na osnovu numeričkih rešenja Boltzmann-ove jednačine. U drugoj celini je razmatran transport elektrona u tečnom argonu, tečnom kriptonu i tečnom ksenonu primenom Monte Carlo simulacija. Proučavani su uticaji efekata koherentnog rasejanja i različitih načina za aproksimaciju neelastičnih sudara u tečnoj fazi na izračunate vrednosti transportnih koeficijentata u ovim tečnostima. Poseban akcenat je stavljen na proučavanje strukturno indukovane negativne diferencijalne provodnosti u tečnom ksenonu na osnovu prostorno razloženih karakteristika roja i funkcija raspodele elektrona. Transportni koeficijenti za rojeve elektrona u atomskim tečnostima su iskorišćeni kao ulazni podaci u 1.5-dimenzionom klasičnom fluidnom modelu prvog reda i u fluidnom modelu zasnovanom na razvoju izvornog člana u jednačini kontinuiteta po gradijentima koncentracije. Ovi fluidni modeli upotrebljeni su za ispitivanje tranzicije lavina elektrona u strimere i propagacije negativnih strimera u atomskim tečnostima visoke mobilnosti. Pored toga, na osnovu ovih modela je razmatrano na koji način različit tretman neelastičnih sudara, priroda transportnih koeficijenata i rekombinacija kvazislobodnih elektrona i pozitivnih šupljina utiču na dinamiku i osobine strimerske plazme., The present doctoral dissertation contains two parts. The first part deals with the study of the third-order transport coefficients of charged-particle swarms in gases. The structure of the third-order transport tensor has been determined by employing the group projector technique in all configurations of electric and magnetic fields. The physical interpretation of the individual components of this tensor has been analyzed by employing the flux gradient relation and the generalized diffusion equation. The variation of the third-order transport coefficients with the reduced electric field and their sensitivity to elementary scattering processes have been determined for a wide range of model and real gases by using Monte Carlo simulations and the numerical solutions of the Boltzmann equation. The second part of this thesis deals with the transport of electrons in liquid argon, liquid krypton and liquid xenon by employing Monte Carlo simulations. The sensitivity of the calculated values of the transport properties in these liquids to coherent scattering effects and different approximations of inelastic scattering in the liquid phase has been investigated. A special emphasis has been placed on the study of the kinetic phenomenon of negative differential conductivity in liquid xenon by using spatially resolved swarm data and electron energy distribution functions. Transport coefficients of electron swarms in atomic liquids are used as input data in 1.5 dimensional classical first order fluid model, as well as in the fluid model which is based on the density gradient expansion of the source term in the equation of continuity. Both fluid models are employed in investigating the transition of electron avalanches into streamers and the propagation of negative streamers in high-mobility atomic liquids. In addition, the presented models are used for investigating how the dynamics and properties of the streamer plasma are influenced by the different treatment of inelastic colli

Poslednjih godina raste interesovanje za plazme koje nastaju u parama tečnosti, na granici gas–tečnost i u samojtečnosti. Ovo je posledica velikog broja raznovrsnih primena koje ove plazme nalazeu biomedicini, nanotehnologiji, industriji goriva, sintezi i obradi materijala, zaštiti životne sredinei tretmanu otpadnih voda.Sve navedene primene koriste neravnotežne plazme koje rade, kako naniskom tako i atmosferskom pritisku, bilo u tečnosti, u višefaznom okruženju (u mehurićima gasa unutar tečnosti)ili gasu/pari.Ipak, nedovoljno poznavanje osnovnih procesa kao i mali broj dostupnih podataka, posebno o koncentracijama reaktivnih vrsta u pražnjenjima u mehurićima i pražnjenjima unutar tečnosti, još uvek predstavljaju jedan od glavnih problema..., In recent years there has been a growing interest in plasmas generated in vapours of liquids, at the gas‒liquid interface and in the liquid itself. This is theconsequence ofalarge number of diverse applications that these plasmas havein biomedicine, nanotechnology, the fuel industry, material synthesis and processing, environmental remediation,and wastewater treatments.All of these applicationsuse non‒equilibrium plasmas that operate at both low and atmospheric pressure, either in a liquid, in a multiphase environment (in gas bubbles within a liquid)or in a gas/vapour. However, currently the main problemwithin the fieldis insufficient understanding and lack of availabledata, especially on concentration of reactive species in discharges in bubbles and intheliquid itself...

Zbog velike zastupljenosti radiofrekvencijskih (RF) plazmi u industriji javila se potreba za definisanjem osnovnih fizičkih principa koji određuju proboj u RF električnim poljima. Uslovi, u vidu probojnog napona i pritiska, mogu se prikazati naponskom probojnom krivom, predstavljenom u V-p ravni. Oblik i položaj krive definisani su kako prirodom pozadinskog gasa tako i karakteristikama spoljašnjeg RF električnog izvora. Ova disertacija ima za cilj da nedvosmisleno definiše fizičke procese koji su odgovorni za proboj pri RF električnim poljima. Za to je korišćena Monte Karlo tehnika. Odabirom slučajnih brojeva, uz poznavanje preseka za određene procese, moguće je verno (čak se može tvrditi egzaktno) opisati kretanje roja naelektrisanih čestica između dve elektrode koje su pobuđene RF generatorom. Izgradnja modela je započeta posmatranjem kretanja elektrona u argonu pri frekvenciji od 13,56 MHz. Na primeru argona objašnjeni su osnovni mehanizmi proboja koji definišu oblik naponske probojne krive. Nadogradnja modela, kao verodostojne predstave RF proboja, uključuje efekte na površinama elektroda (refleksiju i emisiju sekundarnih elektrona), uticaj promene frekvencije i dvofrekvencijskih izvora, kao i teških čestica. Model je primenjen na različite gasove: helijum, kiseonik, sintetički vazduh i atmosfera Marsa., The wide range of radiofrequency (RF) plasma applications in industry rely on research of fundamental physical processes responsible for the RF breakdown. Conditions, such as the breakdown voltage and pressure, can be presented by breakdown voltage curves in the V-p plane. The shape and coordinates of the curve are defined by the nature of the background gas and characteristics of the applied RF electric field. The goal of this dissertation is to define physical processes responsible for the RF breakdown. For that purpose a Monte Carlo computational code has been used. If one knows cross sections for different processes by employing a random number generator, the transport of electrons between two electrodes can be determined. The development of the RF breakdown model begun by observing the motion of electrons in argon at the field frequency of 13.56 MHz. Argon was used to explain the basic mechanisms that define the shape of the breakdown voltage curve. Further upgrade of the model involved inclusion of the surface effects on electrodes (reflection and secondary electron emission), the influence of frequency and dual frequency RF power supplies, as well as the influence of heavy particles on the breakdown. The model was applied to different gases: helium, oxygen, and synthetic air, as well as the atmosphere of Mars.

The study aims to evaluate the effects of non-thermal atmospheric plasma (NTAP) treatments on dentin wetting and surface free energy (SFE) and compare the effects of NTAP treatment, etch-and-rinse, and self-etch protocols for application of universal adhesives. Materials and methods: Mid-coronal dentin of intact third molars was used to measure contact angles of distilled water, ethylene-glycol, and diiodomethane and calculate SFE following different NTAP preset treatments (feeding gas consisting of pure He, He + 1% O 2 , He + 1.5% O 2 ), power input (1 or 3 W), and tip-to-surface distance (2, 4, or 8 mm). Contact angles of reference liquids and SFE of dentin following He + 1.5% O 2 at 3-W and 4-mm treatment was compared to phosphoric acid etching. Contact angles of Single Bond Universal (SBU; 3M ESPE) and Clearfil Universal Bond (CUB; Kuraray Noritake) were measured following NTAP, etch-and-rinse, and self-etch protocols. Results: NTAP significantly reduced contact angles of reference liquids and increased dentin SFE compared to untreated dentin (p < 0.05). O 2 intensified the effect of He NTAP (p < 0.05). NTAP and phosphoric acid increased dentin polarity and Lewis base surface characteristics. Phosphoric acid increased contact angles of adhesives compared to the self-etch protocol (p < 0.05). NTAP resulted in lower adhesive contact angles than phosphoric acid, the difference being statistically significant for CUB (p [removed] 0.05). Conclusions: He NTAP with and without O 2 increased dentin wetting and SFE, surpassing the effect of phosphoric acid and lowering adhesive contact angles. NTAP produced no apparent micro-morphological changes on dentin surface comparable to acid etching. Clinical significance: NTAP treatment of dentin prior to adhesive application increases dentin wetting and surface free energy facilitating better adhesive distribution on dentin surface compared to phosphoric acid etching and similar to the “self-etch” application protocol.