Drift resonance of impurity ions in a toroidal magnetic trap with rotational transform

Shishkin, A.A.; Zolotukhin, A. V.

doi:10.1063/1.1319641

Cited by 4 publications

(3 citation statements)

References 11 publications

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“…If we take a look at a vertical cross-section of the magnetic surfaces and overlay the data calculated separately for both magnetic field perturbations on the same figure (see figure 11(a)) we can see that these islands overlap and satisfying the Chirikov criterion should create a magnetic stochastic layer. To estimate the criterion just to realize how far above overlap the perturbation amplitudes are we solve the linearized equation for the magnetic surface function B∇δψ = −δB∇ψ, (24) where ψ represents the magnetic surface function for closed magnetic surfaces associated with the unperturbed magnetic field B, and δψ reflects the perturbation for the surface function resulting from the magnetic field perturbation δB.…”

Section: Tungsten Transport In Nonergodic and Ergodic Configurationsmentioning

confidence: 99%

“…The result of the calculation presented in this paper demonstrates the capacity of the stochastic layer to reduce impurity transport towards the fusion plasma core on a time interval which is larger by a factor of 15 than the energy confinement time τ E = 1.62 s required for the HELIAS reactor. Together with mechanisms for the impurity transport control, which are based on time-dependent magnetic field perturbations [23,24] the steady-state stochastic layer is considered as a candidate to prevent impurity penetration into the plasma core.…”

Section: Summary and Future Directionsmentioning

confidence: 99%

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Numerical analysis of tungsten transport in drift-optimized stellarator with ergodic and nonergodic plasma configurations

2007

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The radial transport of tungsten ions in a fusion plasma of the HELIAS stellarator with five magnetic field periods is studied by means of a new numerical code. The code solves guiding center equations for test particles (tungsten ions) with the use of a Runge–Kutta integrating scheme. Coulomb scattering of the tungsten ions on the background plasma particles (electrons, deuterons and tritons) is simulated by means of a discretized collision operator based on the binomial distribution and presented in terms of pitch-angle scattering and energy slowing down and scattering. The coronal model is used to determine the mean charge state of the tungsten ion ensemble ⟨Z(Te, ne)⟩ as a function of background electron temperature and density. Two plasma configurations with and without ergodic confinement regions and both with finite plasma pressure of β = 3% are considered. The nonergodic configuration possesses closed nested magnetic surfaces throughout the entire confinement volume. The ergodic magnetic field configuration is represented through additional magnetic field perturbations. Comparative analysis of the radial transport is performed for a time interval greater by a factor of 15 than the energy confinement time τE = 1.62 s required for the HELIAS reactor. In spite of the fact that the tendency of impurities to penetrate towards the plasma core is observed in both cases, the stochastic scenario exhibits reduced inward impurity flux.

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Section: Tungsten Transport In Nonergodic and Ergodic Configurationsmentioning

confidence: 99%

Section: Summary and Future Directionsmentioning

confidence: 99%

Numerical analysis of tungsten transport in drift-optimized stellarator with ergodic and nonergodic plasma configurations

2007

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“…Different approaches to control the particle motion exist, one of which is to apply magnetic field perturbations to produce resonance trajectories -drift islands, overlapping of these islands and stochastic trajectories that lead, for example, to the removal of test particles from the centre of the magnetic configuration to the periphery [1,2]. Drift island motion, without overlapping of resonances, is possible [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

Estafette of drift resonances, stochasticity and control of particle motion in a toroidal magnetic trap

Shishkin

2002

Nucl. Fusion

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A new method of particle motion control in toroidal magnetic traps with a rotational transform using an estafette of drift resonances and stochasticity of particle trajectories is proposed. The use of the word estafette here means that particles pass through a set of resonances in consecutive order from one to another during their motion. The overlapping of adjacent resonances can be moved radially from the centre to the edge of the plasma by switching on the corresponding perturbations at times in accordance with a particular rule. In this way, particles (e.g., cold alpha particles) can be removed from the centre of the confinement volume to the plasma periphery. For an analytical treatment of the stochastic behaviour of particle motion, the equation for the drift surface function Ψ* (r,ϑ,φ,V∥,V⊥,t) = const is reduced to a diffusion type equation in the case when some adjacent resonances take place and the stochastic diffusion coefficients Dr,r, Dr,ϑ and Dϑ,ϑ in the real space variables are introduced. This new approach is demonstrated by numerical computations of test helium particle trajectories in the LHD toroidal trap.

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Removal of cold alpha particles from helical device for fusion

Shishkin¹,

Antufyev²,

Motojima³

et al. 2006

Fusion Engineering and Design

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Drift resonance of impurity ions in a toroidal magnetic trap with rotational transform

Cited by 4 publications

References 11 publications

Numerical analysis of tungsten transport in drift-optimized stellarator with ergodic and nonergodic plasma configurations

Numerical analysis of tungsten transport in drift-optimized stellarator with ergodic and nonergodic plasma configurations

Estafette of drift resonances, stochasticity and control of particle motion in a toroidal magnetic trap

Removal of cold alpha particles from helical device for fusion

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