Radial Drift Invariant In Long-Thin Mirrors
2012 (English)In: Fusion for Neutrons and Subcritical Nuclear Fission: Fusion for Neutrons and Subcritical Nuclear Fission / [ed] Jan Källne, Dimitri Ryutov, Giuseppe Gorini, Carlo Sozzi, Marco Tardocchi, 2012, 255-258 p.Conference paper (Refereed)
In omnigenous systems, the guiding centers are constrained to move on magnetic surfaces. Since a magnetic surface is determined by a constant radial Clebsch coordinate, omnigenuity implies that the guiding center radial coordinate (the Clebsch coordinate) is constant. Near omnigenuity is probably a requirement for high quality confinement and in such systems only small oscillatory radial banana guiding center excursions from the average drift surface occur. The guiding center radial coordinate is then the leading order term for a more precise radial drift invariant I-r, where higher order corrections arise from the oscillatory "banana ripple" associated with the excursions from the mean drift magnetic surface. An analytical expression for the radial invariant is derived for long-thin quadrupolar mirror equilibria. The formula for the invariant is then used in a Vlasov distribution function. To model radial density profiles, it is necessary to use the radial invariant (the parallel invariant is insufficient for this). The results are also compared with standard fluid approaches. In several aspects, the fluid and Vlasov system with the radial invariant give analogous formulas. One difference is that the parallel current associated with finite banana widths could be derived from the radial invariant.
Place, publisher, year, edition, pages
2012. 255-258 p.
, AIP Conference Proceedings, ISSN 0094-243X ; 1442
Mirror machine, constant of motion, radial invariant
Engineering and Technology
Research subject Engineering Science with specialization in Science of Electricity
IdentifiersURN: urn:nbn:se:uu:diva-181211DOI: 10.1063/1.4706876ISI: 000306895100029ISBN: 978-0-7354-1038-1OAI: oai:DiVA.org:uu-181211DiVA: diva2:556102
International Workshop on Fusion Neutrons and Subcritical Nuclear Fission (FUNFI), SEP 12-15, 2011, Varenna, ITALY