Non-linear dynamics of Alfvén eigenmodes excited by thermonulcear alpha particles in the presence of ion cyclotron resonance heating
2007 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 47, no 9, 1131-1141 p.Article in journal (Refereed) Published
Alfvén eigenmodes (AEs) excited by thermonuclear α-particles can degrade the heating efficiency by spatial redistribution of the resonant α-particles. Changes of the orbit invariants in phase space by collisions and interactions with other waves, such as magnetosonic waves during ion cyclotron resonance heating (ICRH), lead to changes in the phase between the α-particles and AEs, causing a decorrelation of the interactions and stronger redistribution of the α-particles. Cyclotron interactions increase the decorrelation of the AE interactions with the high-energy ions and hence a stronger radial redistribution of the high-energy α-particles by the AEs. Renewal of the distribution function by thermonuclear reactions and losses of α-particles to the wall lead to a continuous drive of the AEs and a radial redistribution of the α-particles. The condition for excitation of AEs is shown to depend on the heating scenario where heating at the low field side creates a significant population of high-energy non-standard orbits which drive the modes. The redistribution results in a reduction in the averaged α-particle energy and a degradation of the heating efficiency. The effect on the distribution function in the presence of several unstable modes is not additive and the particle redistribution is found to saturate with an increasing number of modes.
Place, publisher, year, edition, pages
2007. Vol. 47, no 9, 1131-1141 p.
Alpha particles; Cyclotron resonance; Distribution functions; High energy physics; Plasma heating; Thermonuclear reactions; Ion cyclotron resonance heating (ICRH); Magnetosonic waves; Excitation energy
Other Electrical Engineering, Electronic Engineering, Information Engineering
IdentifiersURN: urn:nbn:se:kth:diva-6937DOI: 10.1088/0029-5515/47/9/009ISI: 000249968800012ScopusID: 2-s2.0-34548217149OAI: oai:DiVA.org:kth-6937DiVA: diva2:11790
QC 201006282007-03-292007-03-292012-03-22Bibliographically approved