Fys-2001 Statistisk fysikk og termodynamikk
Fys-3017/8017: Sheaths and probes in low-temperature plasmas . See below for new course description and contact me before end of October 2017 if you are interested in this course spring 2017.
Possible MSc projects (30 eller 60 stp):
-Electron energy distributions in double layer conditions
- Anode double layers in weakly magnetized plasmas
- Vacuum arcs
Suitable 10 stp bachelor project preparing for the Master project can be carried out as elective course prior to a 30 stp project.
Course description Fys-3017:
FYS-1002 Electromagnetism, Fys- 2001 Statistical physics and thermodynamics, FYS-2009 Introduction to plasma physics, Fys-3000 Introduction to satellite and rockets techniques and space instrumentations.
Plasma interaction with walls, e.g. a probe surface, spacecraft or a dust particle in space, leads to formation of plasma sheaths between the plasma and the wall. Such sheaths can sustain large potential drops over a distance of a few Debye lengths, caused either by applied bias, charging of satellites in space or charged dust particles. Charging of spacecrafts can lead to unwanted arcing and damaging of instruments, and hence this mechanism needs to be understood in order optimize spacecraft and diagnostic design in space. Most important, to obtain plasma parameters from probes it is crucial to understand how sheaths form and how the plasma interacts with walls through a sheath.
The course starts with introducing collisions and collisional cross sections and then goes on to study plasma flux towards walls in plasmas and formation of various types of sheaths. Charging effects on objects in space will be covered. Finally, probe measurements of plasma parameters in low-temperature plasmas will be studied, which pertains to laboratory plasmas as well as space plasmas. The course provides insight in theory and practical applications of probe techniques in laboratory and space. The theory to obtain plasma parameters from Langmuir diagnostics, ion- energy analyzers, emissive probes, Mach probes, and mass spectrometry will be covered in some detail. In addition, the dust instruments developed and implemented at UiT for mesospheric rockets will be introduced.
Laboratory exercises are central in understanding the various probe methods. Five to six laboratory exercises will be performed, of which a minimum of three laboratory reports with full characterization of a plasma by means of at least three different probe methods needs to be approved prior to final examination, of which one report will count 20% at the final examination.
Prior to the laboratory experiments, necessary safety instructions are given.
Objective of the course
Knowledge - The student will be able to:
- explain the characteristics of various probe sheaths and understand the basics of charging of dust and spacecraft in space plasmas.
- understand the interactions between plasmas and walls
- understand and apply the theory needed to analyse probe measurements in low-temperature plasmas
- explain typical probes applied to measurements in laboratory and space.
Skills - The student will be able to
- calculate sheath thickness for various conditions and charging effects on objects in space plasmas
- set up simple measurement circuitry for probes and perform measurements in laboratory plasmas
- analyse plasma parameters from probe measurements and assess their accuracy
- design probes for various low-temperature plasmas in laboratory and space.