Vis enkel innførsel

dc.contributor.authorSamant, O.
dc.contributor.authorDendy, R.O.
dc.contributor.authorChapman, Sandra
dc.contributor.authorMoseev, D.
dc.contributor.authorOchoukov, R.
dc.date.accessioned2024-08-27T08:38:55Z
dc.date.available2024-08-27T08:38:55Z
dc.date.issued2024-04-02
dc.description.abstractMeasurements of ion cyclotron emission (ICE) are planned for magnetically confined fusion plasmas heated by neutral beam injection (NBI) in the Wendelstein 7-X stellarator (W7-X). Freshly injected NBI ions in the edge region, whose velocity-space distribution function approximates a delta-function, are potentially unstable against the magnetoacoustic cyclotron instability (MCI), which could drive a detectable ICE signal. Prediction of ICE from NBI protons in W7-X hydrogen plasmas is challenging, owing to the low ratio of the ions’ perpendicular velocity to the local Alfvén speed, v<sub>⊥(NBI)</sub>/V<sub>A</sub> ≃ 0.14. We address this from first principles, using the particle-in-cell kinetic code EPOCH. This self-consistently solves the Lorentz force equation and Maxwell’s equations for tens of millions of computational ions (both thermal majority and energetic NBI minority) and electrons, fully resolving gyromotion and hence capturing the cyclotron resonant phenomenology which gives rise to ICE. Our simulations predict an ICE signal which is predominantly electrostatic while incorporating a significant electromagnetic component. Its frequency power spectrum reflects novel MCI physics, reported here for the first time. The NBI ions relaxing under the MCI first drive broadband field energy at frequencies a little below the lower hybrid frequency ω<sub>LH</sub>, across the wavenumber range kω<sub>c</sub>/V<sub>A</sub> = 40–60, where ω<sub>c</sub> and V<sub>A</sub> denote ion cyclotron frequency and Alfvén velocity. Nonlinear coupling between these waves then excites spectrally structured ICE with narrow peaks, at much lower frequencies, typically the proton cyclotron frequency and its lower harmonics. The relative strength of these peaks depends on the specifics of the NBI ion velocity-space distribution and of the local plasma conditions, implying diagnostic potential for the predicted ICE signal from W7-X.en_US
dc.identifier.citationSamant, Dendy, Chapman, Moseev, Ochoukov. Predicting ion cyclotron emission from neutral beam heated plasmas in Wendelstein7-X stellarator. Nuclear Fusion. 2024;64(5)en_US
dc.identifier.cristinIDFRIDAID 2261728
dc.identifier.doi10.1088/1741-4326/ad36d4
dc.identifier.issn0029-5515
dc.identifier.issn1741-4326
dc.identifier.urihttps://hdl.handle.net/10037/34429
dc.language.isoengen_US
dc.publisherIOP Publishingen_US
dc.relation.journalNuclear Fusion
dc.relation.projectIDinfo:eu-repo/grantAgreement/EC/H2020/101052200/EU/Implementation of activities described in the Roadmap to Fusion during Horizon Europe through a joint programme of the members of the EUROfusion consortium/EUROfusion/en_US
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2024 The Author(s)en_US
dc.rights.urihttps://creativecommons.org/licenses/by/4.0en_US
dc.rightsAttribution 4.0 International (CC BY 4.0)en_US
dc.titlePredicting ion cyclotron emission from neutral beam heated plasmas in Wendelstein7-X stellaratoren_US
dc.type.versionpublishedVersionen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


Tilhørende fil(er)

Thumbnail

Denne innførselen finnes i følgende samling(er)

Vis enkel innførsel

Attribution 4.0 International (CC BY 4.0)
Med mindre det står noe annet, er denne innførselens lisens beskrevet som Attribution 4.0 International (CC BY 4.0)