Alfvén wave driving forces and plasma flow in tokamak plasmas

Elfimov, A. G.; Galvão, R. M. O.; Nascimento, I. C.; Segundo, Gesil Sampaio Amarante

doi:10.1088/0741-3335/40/4/002

Cited by 16 publications

(24 citation statements)

References 25 publications

(45 reference statements)

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“…Using continuity and induction equations, the electromagnetic stress force can be represented as the sum [7,8] of a gradient part, F ͑a͒ ≠,u 1͑͞2rv͒ Im= r ͑rj r E ‫ء‬ u ͒ and F ͑a͒ ≠,z 1͑͞2v͒ Im= r ͑j r E ‫ء‬ z ͒, and a wave momentum transfer force W ͑a͒ k͞v, which is proportional to wave dissipation, W ͑a͒ j ͑a͒ ?Ẽ, wherej ͑a͒ s 2iv͑͞4p͒ P p´͑ a͒ spẼ p . The poloidal component of the viscosity force can be represented as the sum of the neoclassical ion viscosity force [3,6], F p neo,u m neo V 0u (m neo is the ion viscosity coefficient), and the collisionless gyroviscosity force [14],…”

Section: Ion Larmour Radius Effect On Rf Ponderomotive Forces and Indmentioning

confidence: 99%

“…The relations between the oscillating current and velocity and the components of the rf electric fields are determined by the dielectric tensor´͑ a͒ sp (see, for example, Refs. [8,13]):…”

Section: Ion Larmour Radius Effect On Rf Ponderomotive Forces and Indmentioning

confidence: 99%

“…It may decrease the turbulence level by shearing decorrelation mechanisms [3] and cause ion banana orbit squeezing by the associated radial electric field shear [4,5], modifying therefore the heat diffusion coefficient and the outward radial transport. Several mechanisms have been proposed to generate sheared plasma rotation, including neutral beam injection [1,2], Reynolds stress [3,6], and general ponderomotive forces [7,8] driven by radio-frequency (rf) fields. The idea to use forces driven by Alfvén waves to reduce radial transport has a rather long history [3,9].…”

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Ion Larmour Radius Effect on rf Ponderomotive Forces and Induced Poloidal Flow in Tokamak Plasmas

et al. 2000

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Analytical approximations are used to clarify the effect of Larmour radius on rf ponderomotive forces and on poloidal flows induced by them in tokamak plasmas. The electromagnetic force is expressed as a sum of a gradient part and of a wave momentum transfer force, which is proportional to wave dissipation. The first part, called the gradient electromagnetic stress force, is combined with fluid dynamic (Reynolds) stress force, and gyroviscosity is included into viscosity force to model finite ion Larmour radius effects in the momentum response to the rf fields in plasmas. The expressions for the relative magnitude of different forces for kinetic Alfven waves and fast waves are derived.

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Section: Ion Larmour Radius Effect On Rf Ponderomotive Forces and Indmentioning

confidence: 99%

“…The relations between the oscillating current and velocity and the components of the rf electric fields are determined by the dielectric tensor´͑ a͒ sp (see, for example, Refs. [8,13]):…”

Section: Ion Larmour Radius Effect On Rf Ponderomotive Forces and Indmentioning

confidence: 99%

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confidence: 99%

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Ion Larmour Radius Effect on rf Ponderomotive Forces and Induced Poloidal Flow in Tokamak Plasmas

et al. 2000

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“…According to the theory, ITB appear in tokamaks because of the current profile modification (negative shear) or strongly sheared poloidal rotation [3]. In this line of study, AW are currently being considered as a tool to control current profile and to drive the locally sheared plasma flow in tokamaks [4] because they can deposit energy mainly at the local Alfvén resonance. The idea of heating magnetically confined plasmas by the resonant absorption of RF fields using the local AW resonance began with the theoretical work carried out by Dolgopolov and Stepanov [5], Grossmann and Tataronis [6], and Hasegawa and Chen [7].…”

Section: Introductionmentioning

confidence: 99%

Results of localized Alfvén wave heating in TCABR

Elfimov¹,

Lerche²,

Galvão³

et al. 2004

Braz. J. Phys.

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Using two dimensional numerical codes, we show that the direct electron heating found with electron cyclotron emission (ECE) radiometry is related to local Alfvén wave resonances in Tokamak Chauffage Alfvén Brésilean (TCABR) plasmas. The m/N =1/2, 0/2 and 0/3 modes are dominant in the observed wave heating, due to Alfvén wave continuum absorption. In particular, the resonant absorption of the m = 0 sideband harmonic plays an important role in the central core and peripheral heating. The increase of the electron temperature during the radio frequency pulse was accompanied by a local density rise that produced a cut-off of the ECE emission. The observed heating profile is also consistent with the reflectometer measurements of the density fluctuations induced by radio frequency fields in the local Alfvén wave resonance of the m/N =-1/-2, 1/-3 modes in TCABR.

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“…al. [73]. Esta teoria das forças ponderomotorasé usada no código cilíndrico para a implementação da subrotina "forças ponderomotoras" † .…”

Section: Capítulo 5 Forças Ponderomotorasunclassified

"Teoria e modelamento computacional de aquecimento de plasma por ondas de alfvén no tokamak TCABR"

Sanabria¹

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ResumoNeste trabalho apresentamos o estudo da possivilidade de melhores regimes para o uso dos experimentos de aquecimento e geração de corrente e fluxo de plasma no tokamak TCABR. Apresentamos um estudo dos efeitos de rotação de plasma em baixa freqüência (low-frequency (LF)), penetração de campo eletromagnético, absorção e forças ponderomotoras no "Tokamak Chauffage Alfvén Brésilien" (TCABR) comênfase na faixa de freqüências de 0, 5-10, 0kHz. Os campos de LF são dirigidos pelo limitador magnético ergódico (ergodic magnetic limiter (EML)) no TCABR. Foi feito um estudo analítico das ondas de Alfvén e ressonância usando modelos simples. Um estudo numérico tembém foi realizado utilizando três códigos, quais sejam, o código cinético toroidal, o código cilíndrico e o código ALTOK. AbstractIn this work we present the study of the determination the best regimes and parameters for the heating experiments and current generation and plasma flow in the tokamak TCABR. Study of effects of plasma rotation in low frequency (LF), field penetration, absorption and ponderomotive forces in "Tokamak Chauffage Alfvén Brésilien" (TCABR)is investigated with emphasis in the frequency range of 0, 5-10, 0kHz. The fields of LF are driven by the ergodic magnetic limiter (EML) in TCABR. A qualitative analytical study of the Alfvén waves and their resonances is performed using simple models. A numeric study was carried out using through three codes, called the kinetic totoidal code, the cylindrical code and the ALTOK code.Dedico este trabalho a minha esposa: Ao professor Dr. Artour G. Elfimov pela sua ajuda, sua orientação, e por estar sempre prestes a me ajudar nos momentos difíceis da pesquisa e elaboração desta tese, Ao Carlos Pires pela sua grande ajuda na correção desta tese e pelas suas sugestões que foram de muita importância (obrigadão Carlos), A minha esposa Marcia pela sua ajuda, pelo apoio moral, pela sua compreensão nos momentos de estresse no decorrer destes anos, A minha irmã Gerby, Aos professores do grupo de Física de plasmas pelo apoio brindado, Aos meus amigos do grupo de pesquisa, A todos meus amigos, sem citações porque por desventura poderia esquecer de algum deles, e Um agradecimento especialÀ FAPESP pela ajuda financeira, sem a qual não seria possível a realização deste trabalho. Porém, quando um acoplamento de modos toroidais ocorre, surge uma banda no espectro de freqüências de Alfvén [24]. Automodos com freqüências dentro da banda podem existir; eles são chamados de automodos de banda de Alfvén, ou simplesmente automodos toroidais de Alfvén (TAE). Estes modos podem evitar amortecimento numa faixa do contínuo, e podem ser excitados facilmente através deíons energéticos.A banda TAEé produzida pelo acoplamento toroidal entre os harmônicos poloidais m e (m + 1). A TAEé normalmente especificada por um número de modo toroidal n. A estrutura do modo geralmenteé expressa como uma superposição de muitos harmônicos poloidais. Os campos na banda TAE com modos m e n altos tem um pico próximo do 3 valor q = m/n (Cheng 1991 [...

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Alfvén wave driving forces and plasma flow in tokamak plasmas

Cited by 16 publications

References 25 publications

Ion Larmour Radius Effect on rf Ponderomotive Forces and Induced Poloidal Flow in Tokamak Plasmas

Ion Larmour Radius Effect on rf Ponderomotive Forces and Induced Poloidal Flow in Tokamak Plasmas

Results of localized Alfvén wave heating in TCABR

"Teoria e modelamento computacional de aquecimento de plasma por ondas de alfvén no tokamak TCABR"

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