Multi-fluid MHD model and calculations of Alfvén wave spectrum and dissipation in tokamaks

Галкин, С. А.; Ivanov, A. A.; Medvedev, S. Yu.; Elfimov, A. G.

doi:10.1016/s0010-4655(01)00414-3

Cited by 10 publications

(18 citation statements)

References 14 publications

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“…To calculate LF field excitation in the discussed plasmas we use the cylindrical and toroidal codes mentioned in the introduction [14,15]. The conditions for their validity, away from the rational surfaces where k || = 0, are satisfied in a peripheral (cold plasma) region extending over approximately the outer third of the minor radius, in a frequency band that is determined by inequalities…”

Section: Codes Usedmentioning

confidence: 99%

Low frequency heating and flow driven by the dynamic ergodic divertor in tokamaks

et al. 2004

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The profile and dissipation of the field excited by dynamic ergodic divertor (DED) coils in tokamak plasmas are calculated, and an estimate is made of the poloidal/toroidal velocities driven by this field. The coils are idealized as an inboard sheet current composed of a toroidal sequence of helical line current segments expanded in Fourier series with poloidal/toroidal mode numbers M/N, and mode amplitudes depending on feeding. Numerical calculations with cylindrical and toroidal codes show maxima of field dissipation due to Alfvén wave mode conversion effect taking place at the rational magnetic surfaces where q = M/N. The effects of toroidicity and ion collisions in the dielectric tensor in the upper DED frequency range described (f = 5-10 kHz) are found to be very important in absorption calculations. At the q = 3 resonant magnetic surface typical for DED coil design, it is estimated that ponderomotive forces produced by 20 kW of dissipation can drive local toroidal and poloidal flows of respective orders 8 km s −1 and 10 km s −1 in the TEXTOR tokamak.

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Section: Codes Usedmentioning

confidence: 99%

Low frequency heating and flow driven by the dynamic ergodic divertor in tokamaks

et al. 2004

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“…The plasma profiles used in the ALTOK code are slightly different from the cylindrical representation. The density and current distribution used in ALTOK code [9] are n = n 0 (1 − Ψ 0.7 ), and…”

Section: Plasma Parameters and Lf Fieldsmentioning

confidence: 99%

“…One dimensional numerical kinetic [7,8] (named "cylindrical" hereafter) and two-dimensional fluid [9] ("ALTOK" hereafter) codes were developed for calculations of Alfvén wave excitation and dissipation in axisymmetric tokamaks. The cylindrical code calculates the distribution of electromagnetic fields, dissipation profiles, and the impedance of the helical antenna for a given real frequency ω of the generator and toroidal N = k z R 0 and poloidal M wavenumbers of the antenna, in two-ion species magnetized plasmas with circular concentric magnetic surfaces.…”

Section: Introductionmentioning

confidence: 99%

“…The LF electromagnetic fields are represented as sum of the poloidal Fourier harmonics exp[i(mθ +k z z −ωt)], and the dielectric tensor [7] is calculated from the Vlasov-Boltzmann equation for each harmonic taking into account electron Landau damping, electronion collisions, and finite Larmor radius effect. A multi-fluid plasma model is used in the ALTOK code [9], with two dimensional inhomogeneity and arbitrary cross-section of the tokamak magnetic surface, including the Shafranov shift. In the applications to TCABR, the fields and dissipation are calculated on circular magnetic surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Low frequency fields driven by the Ergodic Magnetic Limiter at rational surfaces in rotating tokamak plasmas

Rondan¹,

Elfimov²,

Galvão³

et al. 2004

Braz. J. Phys.

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The rotating low frequency (RLF) field penetration and dissipation and the effect of ponderomotive forces driven by Ergodic Magnetic Limiter (EML) on the poloidal/ toroidal flow in tokamak plasmas are discussed. EML coils are represented as a sheet current expanded in Fourier series with poloidal/toroidal wave numbers M/N depending on coil shape and feeding. The Alfvén wave mode conversion effect in the RLF range is found responsible for wave dissipation at the rational magnetic surfaces q r = −M/N = 3 typical for EML coil design. Analytical and numerical calculations show maximums of LF field dissipation at the local Alfvén wave resonance ω = |k || cA| near the rational magnetic surface qr = 3 in Tokamak Chauffage Alfvén Brésilien. The poloidal rotation velocity U , taken into account in the dielectric tensor, can strongly modify the LF field and dissipated power profiles. Even stationary EML fields can dissipate at the local Alfvén wave resonance (U M/r A = k c A ). Preliminary estimations show that the stationary EML fields can decelerate the plasma rotation.

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“…Para testar os efeitos toroidais, que faltam no código cilíndrico da seção anterior (2.4.1), para analisar a dissipação da onda de freqüências baixas perto da superfície racional q = M/N = 3/1, usamos o código ALTOK (código bi-dimensional que inclui efeitos toroidais e deslocamento de Shafranov de ∼ 1, 6cm, escrito por S. A. Galkin e colaboradores [63]). …”

Section: Código Toroidal Altokunclassified

"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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Multi-fluid MHD model and calculations of Alfvén wave spectrum and dissipation in tokamaks

Cited by 10 publications

References 14 publications

Low frequency heating and flow driven by the dynamic ergodic divertor in tokamaks

Low frequency heating and flow driven by the dynamic ergodic divertor in tokamaks

Low frequency fields driven by the Ergodic Magnetic Limiter at rational surfaces in rotating tokamak plasmas

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

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