Relativistic Fermi-Ulam map: Application to WEGA stellarator lower hybrid power operation

0430250 - ÚFP 2015 RIV US eng J - Journal Article
Fuchs, Vladimír - Laqua, H.P. - Seidl, Jakub - Krlín, Ladislav - Pánek, Radomír - Preinhaelter, Josef - Urban, Jakub
Relativistic Fermi-Ulam map: Application to WEGA stellarator lower hybrid power operation.
Physics of Plasmas. Roč. 21, č. 6 (2014), 061513-061513. ISSN 1070-664X. E-ISSN 1089-7674.
[Twentieth Topical Conference on Radio Frequency Power in Plasmas. Sorrento, 25.06.2013-28.06.2013]
R&D Projects: GA MŠMT(CZ) LM2011021; GA ČR GP13-38121P; GA ČR GAP205/11/2341; GA ČR GAP205/10/2055
Grant - others:GA MŠk(CZ) LM2010005
Institutional support: RVO:61389021
Keywords : plasma * tokamak
Subject RIV: BL - Plasma and Gas Discharge Physics
Impact factor: 2.142, year: 2014
http://scitation.aip.org/content/aip/journal/pop/21/6/10.1063/1.4884346

Analytical and numerical support is here provided in support of the explanation for the observation of MeV electrons during Lower Hybrid (LH) operation in EC pre-heated plasma at the WEGA stellarator. LH power at 2.45 GHz is radiated into a B ­0.5 T plasma at Te 10 eV with an EC-generated 50 keV population of electrons. In response, fast electrons travel around flux or drift surfaces essentially without collisions, repeatedly interacting with the rf field and gaining energy in the process. We derive here a relativistic generalization of the simplified area-preserving Fermi-Ulam (F-U) map allowing phase-space global stochasticity analysis. At WEGA conditions, and with correlated phases between electron–antenna electric field interaction events, the F-U map and supporting numerical simulations predict an absolute energy barrier around 300 keV. In contrast, with random phases, the electron energy can reach MeV values, compatible with the measurements on WEGA.
Permanent Link: http://hdl.handle.net/11104/0235148