Plasma-wall interactions play an important role in plasma physics. In many theoretical studies an infinite unbounded system is assumed. However in reality, it is often the case that we need to include the physics of the plasma -wall interaction in order to be able to realistically model a plasma system. Such studies are quite complicated due to the non-linear nature of the associated physics. One such example is the source-collector sheath system which describes the plasma between an infinite wall and a Maxwellian source. Such a system comprises of two distinct areas; the first is an electron rich region near the Maxwellian source, the source sheath, and the other is an ion rich area near the wall, the collector sheath. In the first part of this work, we model this system theoretically using truncated Maxwellian distributions for both electrons and ions to describe the collisionless, ionization-free plasma, and we also include flows. Furthermore, we study the problem using simulation results from our Vlasov kinetic code Yggdrasil using a perfectly absorbing wall as a boundary. In the second part of this work, we study the effect of an electron emitting surface in the source-collector sheath system, without plasma flows. Electron emission plays a crucial role for many plasma applications, for example in fusion devices it is an important part of the physics of the interaction of the plasma with the walls of the reactor. A theoretical model is constructed for a range of ion and electron temperatures and for a variety of electron emission characteristics. Furthermore, we use our kinetic code Yggdrasil with an electron emitting boundary to simulate the phenomenon. In the third part of this work, we focus on the application of the theoretical model we developed for the source-collector sheath system in the study of the charging of large dust grains. We use the formalism of the MOML (Modified Orbital Motion Limited) approach incorporating the conclusions of our theoretical studies. More specifically, we investigate how the use of the source-collector sheath model applied in MOML affects its results. The outcomes of this study are compared with numerical studies available in the literature.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:656712 |
| Date | January 2014 |
| Creators | Rizopoulou, Nikoleta |
| Contributors | Coppins, Michael |
| Publisher | Imperial College London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/10044/1/24576 |
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