dc.creator | Zeeland, M. A. van | es |
dc.creator | Heidbrink, W. W. | es |
dc.creator | Sharapov, S. E. | es |
dc.creator | Spong, D. | es |
dc.creator | Cappa, A. | es |
dc.creator | García Muñoz, Manuel | es |
dc.date.accessioned | 2020-08-26T14:59:57Z | |
dc.date.available | 2020-08-26T14:59:57Z | |
dc.date.issued | 2016-11 | |
dc.identifier.citation | Zeeland, M.A.v., Heidbrink, W.W., Sharapov, S.E., Spong, D., Cappa, A. y García Muñoz, M. (2016). Electron cyclotron heating can drastically alter reversed shear Alfven eigenmode activity in DIII-D through finite pressure effects. Nuclear Fusion, 56 (11), 12007. https://doi.org/10.1088/0029-5515/56/11/112007. | |
dc.identifier.issn | 0029-5515 | es |
dc.identifier.uri | https://hdl.handle.net/11441/100460 | |
dc.description.abstract | A recent DIII-D experiment investigating the impact of electron cyclotron heating (ECH)
on neutral beam driven reversed shear Alfvén eigenmode (RSAE) activity is presented. The
experiment includes variations of ECH injection location and timing, current ramp rate, beam
injection geometry (on/off-axis), and neutral beam power. Essentially all variations carried out
in this experiment were observed to change the impact of ECH on AE activity significantly.
In some cases, RSAEs were observed to be enhanced with ECH near the off-axis minimum
in magnetic safety factor (qmin), in contrast to the original DIII-D experiments where the
modes were absent when ECH was deposited near qmin. It is found that during intervals
when the geodesic acoustic mode (GAM) frequency at qmin is elevated and the calculated
RSAE minimum frequency, including contributions from thermal plasma gradients, is very
near or above the nominal TAE frequency (fTAE), RSAE activity is not observed or RSAEs
with a much reduced frequency sweep range are found. This condition is primarily brought
about by ECH modification of the local electron temperature (Te) which can raise both the
local Te at qmin as well as its gradient. A q-evolution model that incorporates this reduction
in RSAE frequency sweep range is in agreement with the observed spectra and appears to
capture the relative balance of TAE or RSAE-like modes throughout the current ramp phase
of over 38 DIII-D discharges. Detailed ideal MHD calculations using the NOVA code show
both modification of plasma pressure and pressure gradient at qmin play an important role
in modifying the RSAE activity. Analysis of the ECH injection near the qmin case where no
frequency sweeping RSAEs are observed shows the typical RSAE is no longer an eigenmode
of the system. What remains is an eigenmode with poloidal harmonic content reminiscent of
the standard RSAE, but absent of the typical frequency sweeping behavior. The remaining
eigenmode is also often strongly coupled to gap TAEs. Analysis with the non-perturbative
gyro fluid code TAEFL confirms this change in RSAE activity and also shows a large drop in
the resultant mode growth rates. | es |
dc.description.sponsorship | RCUK Energy Programme EP/I501045 | es |
dc.format | application/pdf | es |
dc.format.extent | 16 p. | es |
dc.language.iso | eng | es |
dc.publisher | IOP Publishing | es |
dc.relation.ispartof | Nuclear Fusion, 56 (11), 12007. | |
dc.rights | Attribution-NonCommercial-NoDerivatives 4.0 Internacional | * |
dc.rights.uri | http://creativecommons.org/licenses/by-nc-nd/4.0/ | * |
dc.subject | Magnetohydrodynamic waves | es |
dc.subject | Tokamaks | es |
dc.subject | Fusion products effects | es |
dc.subject | Plasma heating by microwaves | es |
dc.subject | Plasma heating by particle beams | es |
dc.title | Electron cyclotron heating can drastically alter reversed shear Alfven eigenmode activity in DIII-D through finite pressure effects | es |
dc.type | info:eu-repo/semantics/article | es |
dcterms.identifier | https://ror.org/03yxnpp24 | |
dc.type.version | info:eu-repo/semantics/publishedVersion | es |
dc.rights.accessRights | info:eu-repo/semantics/openAccess | es |
dc.contributor.affiliation | Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear | es |
dc.relation.projectID | EP/I501045 | es |
dc.relation.publisherversion | http://dx.doi.org/10.1088/0029-5515/56/11/112007 | es |
dc.identifier.doi | 10.1088/0029-5515/56/11/112007 | es |
dc.contributor.group | Universidad de Sevilla. RNM138: Física Nuclear Aplicada | es |
dc.journaltitle | Nuclear Fusion | es |
dc.publication.volumen | 56 | es |
dc.publication.issue | 11 | es |
dc.publication.initialPage | 12007 | es |