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

Journal Article · Sat Jan 01 00:00:00 EST 2011 · Plasma Physics and Controlled Fusion

DOI:https://doi.org/10.1088/0741-3335/53/2/024008· OSTI ID:1028766

Toi, K ^[1]; Ogawa, K ^[2]; Isobe, M ^[1]; Osakabe, M ^[1]; Spong, Donald A ^[3]; Todo, Yasushi ^[1]

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1. National Institute for Fusion Science, Toki, Japan
2. Nagoya University, Japan
3. ORNL

Comprehensive understanding of energetic-ion-driven global instabilities such as Alfven 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.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1028766
• Journal Information: Plasma Physics and Controlled Fusion, Vol. 53, Issue 2; ISSN 0741-3335
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ACOUSTICS
COMPRESSIBILITY
CONFINEMENT
GEODESICS
HELICITY
PLASMA
REVERSED SHEAR
ROTATIONAL TRANSFORM
STELLARATORS
TAIL IONS
TRANSPORT
INDUCED ALFVEN EIGENMODES
LARGE HELICAL DEVICE
DIII-D TOKAMAK
MHD INSTABILITIES
TAE-MODES
TOROIDAL PLASMAS
ALPHA-PARTICLES
TOROIDICITY
STABILITY