The effect of magnetic field modification on heavy ion movement in advanced stellarators and helical devices

Shishkin, A.A.; Shyshkin, Oleg; Wobig, H.; Igitkhanov, Y.; Motojima, O.; Morimoto, S.; Yamazaki, K.; Inagaki, S.

doi:10.1016/s0022-3115(02)01530-1

Cited by 3 publications

(2 citation statements)

References 3 publications

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“…E r is the radial electric field. Considering tungsten ion motion in the stochastic magnetic field produced by overlapping of two adjacent island chains one has to pay attention to the fact that in a collisionless case tungsten ions going around the torus stays within the stochastic layer and oscillates in the radial direction between the inner and outer boundaries of the layer [22]. Taking into account the collisions we include the mechanism for the escaping of impurities from the region of the wandering magnetic field line.…”

Section: Tungsten Transport In Nonergodic and Ergodic Configurationsmentioning

confidence: 99%

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%

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

2007

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“…17 and 18, and experimentally tested on the Saturn stellarator 19 to enhance the plasma confinement time ͑by about 40%͒, by applying an rf electric field with frequency comparable to the bounce frequency ⍀ be of electrons trapped in a helical ripple well in order to enhance their detrapping rate. 21,22 Thus, the additive intuition derives principally from modeling internally generated fluctuations, while the ef intuition derives from externally imposed fluctuations, though the two are different cases of the same phenomenon. 21,22 Thus, the additive intuition derives principally from modeling internally generated fluctuations, while the ef intuition derives from externally imposed fluctuations, though the two are different cases of the same phenomenon.…”

Section: Introductionmentioning

confidence: 99%

The effect on stellarator neoclassical transport of a fluctuating electrostatic spectrum

Mynick

Boozer

2005

Physics of Plasmas

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We study the effect on neoclassical transport of applying a fluctuating electrostatic spectrum, such as produced either by plasma turbulence, or imposed externally. For tokamaks, it is usually assumed that the neoclassical and "anomalous" contributions to the transport roughly superpose, Ò · Ò , an intuition also used in modeling stellarators. An alternate intuition, however, is one where it is the collisional and anomalous scattering frequencies which superpose, · Ò .For nonaxisymmetric systems, in regimes where ¼, this " picture" implies that turning on the fluctuations can decrease the total radial transport. Using numerical and analytic means, it is found that the total transport has contributions conforming to each of these intuitions, either of which can dominate. In particular, for stellarators, the picture is often valid, producing transport behavior differing from tokamaks.

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Controlling the cross-field flux of cold α-particles with resonant magnetic perturbations in a helical fusion plasma device

Shishkin

Sagara²,

Motojima³

et al. 2007

Nucl. Fusion

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A new scenario to control transport of 'cold' α-particles in a helical fusion device by changing poloidal field coil current during plasma discharge is proposed here. A way to enhance radial transport of α-particles in the intermediate energy range is considered which relies on specific features of helical magnetic field. To remove helically trapped, cold α-particles, a β-induced change in the B/B 0 modulation along the particle trajectory is employed. To remove passing particles resonant effects connected with the poloidal field coil currents are used.

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The effect of magnetic field modification on heavy ion movement in advanced stellarators and helical devices

Cited by 3 publications

References 3 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

The effect on stellarator neoclassical transport of a fluctuating electrostatic spectrum

Controlling the cross-field flux of cold α-particles with resonant magnetic perturbations in a helical fusion plasma device

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