TY - JOUR

T1 - The combined toroidicity, ellipticity and triangularity effects on the energy deposition of Alfvén modes in pre-heated, low aspect ratio tokamaks

AU - Cuperman, S.

AU - Bruma, C.

AU - Komoshvili, K.

N1 - Funding Information:
We acknowledge useful discussions and correspondence with N. Fish, A. Kritz, Y.-K.M. Peng, M. Rosenbluth, G. Sewell and H. Strauss. This work was supported in part by the Israeli Ministry of National Infrastructures and Development and by the Israel Atomic Energy Commission.

PY - 2007/3/5

Y1 - 2007/3/5

N2 - The combined plasma non-uniformity effects on the energy deposition of Alfvén waves launched by an external antenna in pre-heated spherical tokamaks are investigated. The following relevant physical processes are here possible: (a) the emergence of gaps in the shear Alfvén continuum spectrum and the generation of discrete global Alfvén eigenmodes with frequencies inside the gaps; (b) multi-wave interactions, interactions of gaps of the same kind (e.g., toroidicity induced) and of different kinds (toroidicity, ellipticity and triangularity induced) as well as of secondary order gaps arising when a pair of modes is coupled to one or more modes through other coupling parameters; (c) basic wave-plasma interactions as propagation, reflection, mode-conversion, tunneling and deposition. Thus, we solved numerically the full 2D wave equations for the vector and scalar potentials, using a quite general two-fluid resistive tensor-operator, without any geometrical limitations. The results obtained indicate the existence of antenna-launched wave characteristics for which the power is most efficiently coupled in outer regions of plasmas, which is of special interest for low aspect ratio tokamaks, e.g., for the generation of non-inductive current drive as well as for turbulence suppression and transport barriers formation.

AB - The combined plasma non-uniformity effects on the energy deposition of Alfvén waves launched by an external antenna in pre-heated spherical tokamaks are investigated. The following relevant physical processes are here possible: (a) the emergence of gaps in the shear Alfvén continuum spectrum and the generation of discrete global Alfvén eigenmodes with frequencies inside the gaps; (b) multi-wave interactions, interactions of gaps of the same kind (e.g., toroidicity induced) and of different kinds (toroidicity, ellipticity and triangularity induced) as well as of secondary order gaps arising when a pair of modes is coupled to one or more modes through other coupling parameters; (c) basic wave-plasma interactions as propagation, reflection, mode-conversion, tunneling and deposition. Thus, we solved numerically the full 2D wave equations for the vector and scalar potentials, using a quite general two-fluid resistive tensor-operator, without any geometrical limitations. The results obtained indicate the existence of antenna-launched wave characteristics for which the power is most efficiently coupled in outer regions of plasmas, which is of special interest for low aspect ratio tokamaks, e.g., for the generation of non-inductive current drive as well as for turbulence suppression and transport barriers formation.

UR - http://www.scopus.com/inward/record.url?scp=33846242496&partnerID=8YFLogxK

U2 - 10.1016/j.physleta.2006.10.038

DO - 10.1016/j.physleta.2006.10.038

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AN - SCOPUS:33846242496

SN - 0375-9601

VL - 362

SP - 305

EP - 323

JO - Physics Letters, Section A: General, Atomic and Solid State Physics

JF - Physics Letters, Section A: General, Atomic and Solid State Physics

IS - 4

ER -