FYS-3017 Sheaths and probes in low-temperature plasmas - 10 stp

The course is available as a singular course, also to students enrolled at other universities in Norway, exchange students and Fullbright students.

The course will only be taught if there are sufficiently many students. Please contact the student adviser as soon as possible if you are interested in following the course.

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 spaceraft can lead to unwanted arcing and damaging of instruments, and hence this mechanism need 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 forms and how the plasma interacts with walls through a sheath.

The course starts with introducing collisions and collisional cross sections and go 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, witch 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 analysers, 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 rocket will be introduced.

Laboratory exercises are central in understanding the various probe methods. Five to six laboratory exercises will be performed, on 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 instructinos are given.

• Applicants from Nordic countries: 1 June for the autum semester and 1 December for the spring semester.
• Exchange students and Fulbright students: 1 October for the spring semester and 15 April for the autum semester.

Admission requirements are a Bachelor's degree in physics or similar education, including specialization in physics worth the equivalent of not less than 80 ECTS credits.

Local admission, application code 9371 - singular courses at Master's level.

Knowledge - The student can

• explain the characteristics of various probe and 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 can

• calculate sheath thickness for various conditions and charging effects on objects in space plasmas
• set ut a simple measurement circuitry for probes and perform measurements in laboratory plasmas
• analyse plasma parameters from probe measurements and assass their accuracy
• design probes for various low-temperature plasmas in laboratiry and space

General expertise - The student can

• look up and work with relevant literature in the field
• understand the applications of in-situ probes as a means to understand plasma processes in laboratory and space
• apply acquired knowledge to laboratory experiments

Lectures: 30 hours

Exercises: 20 hours

Laboratory exercises: 30 hours

Portfolio assessment of laboratory reports counting about 20 % and a final oral examination counting about 80 %. All modules in the portfolio are assessed as a whole and one combined grade is given. Assessment scale: Letter grades A-F.

Re-sit examination (section 22): There is no access to a re-sit examination in this course.

Postponed examination (sections 17 and 21): Students with valid grounds for absence will be offered a postponed examination. Both postponed laboratory exercises and postponed oral examination are arranged during the semester if possible, otherwise early in the following semester.

See indicated sections in Regulations for examinations at the UiT The arctic university of Norway for more information.

Coursework requirements: Access to the final examination requires submission of three approved laboratory reports including one report for portfolio assessment.