Effects of radial particle diffusion on the electron cyclotron absorption coefficient in tokamak plasmas in the presence of lower hybrid waves

Rosa, Paulo Ricardo da Silva; Ziebell, L. F.

doi:10.1088/0741-3335/41/4/005

Cited by 7 publications

(6 citation statements)

References 31 publications

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“…The D ij are defined by D ij = N i N j − N 2 δ ij + ε ij , where the ε ij are the components of the cold plasma dielectric tensor. The expressions for A, B and D are easily found in the literature [9].…”

Section: The Fokker-planck Equation and The Numerical Schemementioning

confidence: 99%

Efficiency of LH current drive in tokamaks featuring an internal transport barrier

Oliveira

Ziebell

Rosa

2005

Plasma Phys. Control. Fusion

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In this paper, we study the effects of the occurrence of radial transport of particles in a tokamak on the efficiency of the current drive by lower hybrid (LH) waves, in the presence of an internal transport barrier. The results are obtained by numerical solution of the Fokker-Planck equation which rules the evolution of the electron distribution function. We assume that the radial transport of particles can be due to magnetic or electrostatic fluctuations. In both cases the efficiency of the current drive is shown to increase with the increase of the fluctuations that originate the transport. The dependence of the current drive efficiency on the depth and position of the barrier is also investigated.

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Section: The Fokker-planck Equation and The Numerical Schemementioning

confidence: 99%

Efficiency of LH current drive in tokamaks featuring an internal transport barrier

Oliveira

Ziebell

Rosa

2005

Plasma Phys. Control. Fusion

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“…The LH diffusion coefficient is proportional to S(s, τ, N ). It can be found in previous works and will not be repeated here [3]. It depends on the perpendicular component of the refraction index N ⊥ , which is obtained from the dispersion relation, for each value of ω and N .…”

Section: The Fokker-planck Equation and The Numerical Schemementioning

confidence: 99%

Effect of radial transport on the LH current drive efficiency in tokamaks featuring an internal transport barrier

2004

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In the present paper we study the effects of occurrence of radial transport of particles in a tokamak, and the effects of the presence of an Internal Transport Barrier (ITB), on the current drive efficiency and power deposition profiles in the case of lower hybrid waves generating an extended tail in the electron distribution function. The results are obtained by numerical solution of the Fokker-Planck equation which rules the evolution of the electron distribution function. We assume that the radial transport of particles is due to magnetic or electrostatic fluctuations, and introduce a model to describe the ITB, with adjustable parameters. The presence of an Edge Transport Barrier (ETB) is simulated by Neumann boundary conditions at the plasma edge. The results obtained show very different behavior for current drive whether we have electrostatic or magnetic transport origin. The change in the plasma current due to magnetic transport has been observed to be more significant than the change due to electrostatic transport, basically because the magnetic transport is more effective in diffusing high-velocity particles of the electron tail.

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“…A useful list of references is given in [20]. This difficulty has meant that the kinetic properties of radio frequency (RF) plasma heating are only studied for homogeneous plasmas or for simple geometries [8,9], it being difficult to introduce three-dimensional real geometry of the plasma confinement devices, especially for complex ones like the TJ-II stellarator [21].…”

Section: The Langevin Equations For Quasi-linear Wave-particle Intera...mentioning

confidence: 99%

“…The Fokker-Planck (FP) equation is solved in stellarators assuming three types of electron populations: circulating ones, and those trapped in wells with and without direct gyrotron heating [8]. A threedimensional (radial dimension plus two dimensions in momentum space) FP equation is solved for a tokamak plasma considering particle diffusion under the effect of anomalous transport [9].…”

Section: Introductionmentioning

confidence: 99%

Langevin equations for quasi-linear wave particle interaction

Castejón

Eguilior

2003

Plasma Phys. Control. Fusion

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The Langevin equations for quasi-linear wave-particle interaction are obtained taking advantage of the unequivocal equivalence between the Fokker-Planck equation and the former ones. The Langevin equations are solved numerically and, hence, the evolution of a single particle embedded in an electromagnetic field in momentum space is obtained. The equations are relativistic and valid for any wave. It is also shown that the stochastic part of the equations is negligible in comparison with the deterministic term, except for the momentum close to the resonance condition for the main parallel refractive index.

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Effects of radial particle diffusion on the electron cyclotron absorption coefficient in tokamak plasmas in the presence of lower hybrid waves

Cited by 7 publications

References 31 publications

Efficiency of LH current drive in tokamaks featuring an internal transport barrier

Efficiency of LH current drive in tokamaks featuring an internal transport barrier

Effect of radial transport on the LH current drive efficiency in tokamaks featuring an internal transport barrier

Langevin equations for quasi-linear wave particle interaction

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