Alfvén eigenmodes and their destabilization by energetic circulating ions in Wendelstein-line stellarators*

Kolesnichenko, Ya. I.; Lutsenko, V. V.; Wobig, H.; Yakovenko, Yu. V.

doi:10.1088/0029-5515/42/8/303

Cited by 10 publications

(4 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The HAE was first predicted by ideal MHD theory [4]. The observation of HAEs in the W7-AS stellarator was suggested in [23,66,67]. Then, the HAE was detected in NBI heated plasmas on LHD at low toroidal field [68].…”

Section: Aes Excited Only In a 3d Plasmamentioning

confidence: 99%

Energetic-ion-driven global instabilities in stellarator/helical plasmas and comparison with tokamak plasmas

Toi¹,

Ogawa

Isobe³

et al. 2011

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

Comprehensive understanding of energetic-ion-driven global instabilities such as Alfvén eigenmodes (AEs) and their impact on energetic ions and bulk plasma is crucially important for tokamak and stellarator/helical plasmas and in the future for deuterium-tritium (DT) burning plasma experiments. Various types of global modes and their associated enhanced energetic ion transport are commonly observed in toroidal plasmas. Toroidicity-induced AEs and ellipticity-induced AEs, whose gaps are generated through poloidal mode coupling, are observed in both tokamak and stellarator/helical plasmas. Global AEs and reversed shear AEs, where toroidal couplings are not as dominant were also observed in those plasmas. Helicity induced AEs that exist only in 3D plasmas are observed in the large helical device (LHD) and Wendelstein 7 Advanced Stellarator plasmas. In addition, the geodesic acoustic mode that comes from plasma compressibility is destabilized by energetic ions in both tokamak and LHD plasmas. Nonlinear interaction of these modes and their influence on the confinement of the bulk plasma as well as energetic ions are observed in both plasmas.In this paper, the similarities and differences in these instabilities and their consequences for tokamak and stellarator/helical plasmas are summarized through comparison with the data sets obtained in LHD. In particular, this paper focuses on the differences caused by the rotational transform profile and the 2D or 3D geometrical structure of the plasma equilibrium. Important issues left for future study are listed.

show abstract

Section: Aes Excited Only In a 3d Plasmamentioning

confidence: 99%

Energetic-ion-driven global instabilities in stellarator/helical plasmas and comparison with tokamak plasmas

Toi¹,

Ogawa

Isobe³

et al. 2011

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

show abstract

“…As the MHD-terms of the model have already been derived by others [8][9][10], those calculations need not be repeated in the present paper. Thus, just a brief overview is given here.…”

Section: A Mhd Partmentioning

confidence: 99%

Numerical investigation of non-perturbative kinetic effects of energetic particles on toroidicity-induced Alfvén eigenmodes in tokamaks and stellarators

2016

View full text Add to dashboard Cite

The resonant interaction of shear Alfvén waves with energetic particles is investigated numerically in tokamak and stellarator geometry using a non-perturbative MHD-kinetic hybrid approach. The focus lies on toroidicity-induced Alfvén eigenmodes (TAEs), which are most easily destabilized by a fast-particle population in fusion plasmas.While the background plasma is treated within the framework of ideal-MHD theory, the drive of the fast particles, as well as Landau damping of the background plasma, is modelled using the drift-kinetic Vlasov equation without collisions. A fast numerical tool, STAE-K, has been developed to solve the resulting eigenvalue problem using a Riccati shooting method. The code, which is suitable for parameter scans, is applied to tokamaks and the stellarator Wendelstein 7-X.Energetic particle modes (EPMs) are found when the pressure of the energetic particles becomes comparable to the pressure of the background plasma. To better understand the physics of EPMs, the connections between TAEs and the shear Alfvén wave continuum are examined. It is shown that, when energetic particles are present, the continuum deforms substantially and the TAE frequency can leave the continuum gap. The interaction of the TAE with the continuum leads to singularities in the eigenfunctions. To further advance the physical model and also to eliminate the MHD continuum together with the singularities in the eigenfunctions, a fourthorder term connected to radiative damping has been included. The radiative damping term is connected to non-ideal effects of the bulk plasma and introduces higher-order derivatives to the model. Thus, it has the potential to substantially change the nature of the solution.For the first time, the fast-particle drive, Landau damping, continuum damping, and radiative damping have been modelled together in tokamak-as well as in stellarator geometry.

show abstract

“…In particular, the compressional Alfvén eigenmode can also be important in spherical tokamaks because of its very high beta values [101]. Alfvén eigenmodes in helical systems are also investigated by Lutsenko [102] and Strauss [86].…”

Section: Role Of Plasma Geometrymentioning

confidence: 99%

Summary: theory of magnetic confinement

Itoh

2003

Nucl. Fusion

View full text Add to dashboard Cite

show abstract

Alfvén eigenmodes and their destabilization by energetic circulating ions in Wendelstein-line stellarators*

Cited by 10 publications

References 14 publications

Energetic-ion-driven global instabilities in stellarator/helical plasmas and comparison with tokamak plasmas

Energetic-ion-driven global instabilities in stellarator/helical plasmas and comparison with tokamak plasmas

Numerical investigation of non-perturbative kinetic effects of energetic particles on toroidicity-induced Alfvén eigenmodes in tokamaks and stellarators

Summary: theory of magnetic confinement

Contact Info

Product

Resources

About