The Library
Alfven cascades in JET discharges with NBI-heating
Tools
Sharapov, S. E. (Sergei E.), Alper, B., Baranov, Yu. F., Berk, H. L., Borba, D., Boswell, C., Breizman, B. N., Challis, C. D., de Baar, M., De la Luna, E., Evangelidis, E. A., Hacquin, S., Hawkes, N. C., Kiptily, V. G., Pinches, Simon David, Sandquist, P., Voitsekhovich, I. and Young, N. P. (2006) Alfven cascades in JET discharges with NBI-heating. In: 9th IAEA Technical Meeting on Energetic Particles in Magnetic Confinements Systems, Takayama, JAPAN, NOV 09-11, 2005. Published in: NUCLEAR FUSION, 46 (10). S868-S879. doi:10.1088/0029-5515/46/10/S02 ISSN 0029-5515.
Research output not available from this repository.
Request-a-Copy directly from author or use local Library Get it For Me service.
Official URL: http://dx.doi.org/10.1088/0029-5515/46/10/S02
Abstract
Alfven cascade (AC) eigenmodes excited by energetic ions accelerated with ion-cyclotron resonance heating in JET reversed-shear discharges are studied experimentally in high-density plasmas fuelled by neutral beam injection (NBI) and by deuterium pellets. The recently developed O-mode interferometry technique and Mirnov coils are employed for detecting ACs. The spontaneous improvements in plasma confinement (internal transport barrier (ITB) triggering events) and grand ACs are found to correlate within 0.2 s in JET plasmas with densities up to similar to 5 x 10(19) m(-3). Measurements with high time resolution show that ITB triggering events happen before 'grand' ACs in the majority of JET discharges, indicating that this improvement in confinement is likely to be associated with the decrease in the density of rational magnetic surfaces just before q(min) (0 passes an integer value. Experimentally observed ACs excited by sub-Alfvenic NBI-produced ions with parallel velocities as low as V-parallel to NBI approximate to . 0.2 . V-A are found to be most likely associated with the geodesic acoustic effect that significantly modifies the shear-Alfven dispersion relation at low frequency. Experiments were performed with a tritium NBI-blip (short time pulse) into JET plasmas with NBI-driven ACs. Although considerable NBI-driven AC activity was present, good agreement was found both in the radial profile and in the time evolution of DT neutrons between the neutron measurements and the TRANSP code modelling based on the Coulomb collision model, indicating the ACs have at most a small effect on fast particle confinement in this case.
Item Type: | Conference Item (UNSPECIFIED) | ||||
---|---|---|---|---|---|
Subjects: | Q Science > QC Physics | ||||
Journal or Publication Title: | NUCLEAR FUSION | ||||
Publisher: | INT ATOMIC ENERGY AGENCY | ||||
ISSN: | 0029-5515 | ||||
Official Date: | October 2006 | ||||
Dates: |
|
||||
Volume: | 46 | ||||
Number: | 10 | ||||
Number of Pages: | 12 | ||||
Page Range: | S868-S879 | ||||
DOI: | 10.1088/0029-5515/46/10/S02 | ||||
Publication Status: | Published | ||||
Title of Event: | 9th IAEA Technical Meeting on Energetic Particles in Magnetic Confinements Systems | ||||
Location of Event: | Takayama, JAPAN | ||||
Date(s) of Event: | NOV 09-11, 2005 |
Data sourced from Thomson Reuters' Web of Knowledge
Request changes or add full text files to a record
Repository staff actions (login required)
View Item |