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Title: Theory on excitations of drift Alfvén waves by energetic particles. I. Variational formulation

A unified theoretical framework is presented for analyzing various branches of drift Alfvén waves and describing their linear and nonlinear behaviors, covering a wide range of spatial and temporal scales. Nonlinear gyrokinetic quasineutrality condition and vorticity equation, derived for drift Alfvén waves excited by energetic particles in fusion plasmas, are cast in integral form, which is generally variational in the linear limit; and the corresponding gyrokinetic energy principle is obtained. Well known forms of the kinetic energy principle are readily recovered from this general formulation. Furthermore, it is possible to demonstrate that the general fishbone like dispersion relation, obtained within the present theoretical framework, provides a unified description of drift Alfvén waves excited by energetic particles as either Alfvén eigenmodes or energetic particle modes. The advantage of the present approach stands in its capability of extracting underlying linear and nonlinear physics as well as spatial and temporal scales of the considered fluctuation spectrum. For these reasons, this unified theoretical framework can help understanding experimental observations as well as numerical simulation and analytic results with different levels of approximation. Examples and applications are given in Paper II [F. Zonca and L. Chen, “Theory on excitations of drift Alfvén waves by energeticmore » particles. II. The general fishbone-like dispersion relation,” Phys. Plasmas 21, 072121 (2014)].« less
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. ENEA C. R. Frascati, Via E. Fermi 45, CP 65-00044 Frascati (Italy)
  2. (China)
  3. Institute for Fusion Theory and Simulation and Department of Physics, Zhejiang University, Hangzhou 310027 (China)
  4. (United States)
Publication Date:
OSTI Identifier:
22299811
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 21; Journal Issue: 7; Other Information: (c) 2014 EURATOM; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; APPROXIMATIONS; COMPUTERIZED SIMULATION; DISPERSION RELATIONS; EXCITATION; FLUCTUATIONS; KINETIC ENERGY; NONLINEAR PROBLEMS; PLASMA; VARIATIONAL METHODS