The Helically Symmetric Experiment, (HSX) Goals, Design and Status

Anderson, F. S. B.; Almagri, A. F.; Anderson, David T.; Matthews, P. G.; Talmadge, J. N.; Shohet, J. L.

doi:10.13182/fst95-a11947086

Cited by 176 publications

(173 citation statements)

References 3 publications

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“…The Helically Symmetric eXperiment (HSX) [2] was designed to have a magnetic field strength that is constant in a helical direction on a flux surface. It has been demonstrated experimentally that quasihelical symmetry (QHS) leads to reduced particle, momentum, and electron heat transport, consistent with predictions from neoclassical theory [3].…”

mentioning

confidence: 99%

Effect of Quasihelical Symmetry on Trapped-Electron Mode Transport in the HSX Stellarator

et al. 2008

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This Letter presents theory-based predictions of anomalous electron thermal transport in the Helically Symmetric eXperiment stellarator, using an axisymmetric trapped-electron mode drift wave model. The model relies on modifications to a tokamak geometry that approximate the quasihelical symmetry in the Helically Symmetric eXperiment (particle trapping and local curvature) and is supported by linear 3D gyrokinetic calculations. Transport simulations predict temperature profiles that agree with experimental profiles outside a normalized minor radius of rho>0.3 and energy confinement times that agree within 10% of measurements. The simulations can reproduce the large measured electron temperatures inside rho<0.3 if an approximation for turbulent transport suppression due to shear in the radial electric field is included.

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confidence: 99%

Effect of Quasihelical Symmetry on Trapped-Electron Mode Transport in the HSX Stellarator

et al. 2008

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“…This Letter presents measurements of the flow evolution in the quasisymmetric stellarator helically symmetric experiment (HSX) [8]. It is shown for the first time that the plasma responds to the bias with a two time-scale flow evolution when a biased electrode is used to impulsively spin the plasma.…”

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confidence: 99%

Experimental Evidence of Reduced Plasma Flow Damping with Quasisymmetry

et al. 2005

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Measurements of plasma flow damping have been made in the helically symmetric experiment using a biased electrode to impulsively spin the plasma. There are two time scales in the evolution of the plasma flow, for both the spin-up and relaxation. Compared to a configuration with the quasisymmetry broken, the flow in the quasisymmetric configuration rises more slowly and to a higher value at bias turn-on, and decays more slowly at bias turn-off. The decays of the flows are significantly faster than the neoclassical prediction.

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“…Temperature perturbations and equilibrium temperature gradients are neglected for simplicity. For parameters typical of the HSX, 19 the characteristic growth rates exceed the electron collision frequency. In this regime, the electron inertial effects can dominate plasma resistivity and produce an instability whose growth rate scales with the electromagnetic skin depth.…”

Section: Unified Theory Of Resistive and Inertial Ballooning Modes Inmentioning

confidence: 99%

Unified theory of resistive and inertial ballooning modes in three-dimensional configurations

et al. 2009

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Analytic results for the stability of resistive ballooning modes ͑RBMs͒ and electron inertial ballooning modes are obtained using a two-scale analysis. This work generalizes previous calculations used for axisymmetric ŝ − ␣ geometry ͓R. H. Hastie, J. J. Ramos, and F. Porcelli, Phys. Plasmas 10, 4405 ͑2003͔͒ to general three-dimensional geometry. A unified theory is developed for RBMs and inertial ballooning modes, in which the effects of both ideal magnetohydrodynamic free energy ͑as measured by the asymptotic matching parameter ⌬Ј͒ and geodesic curvature drives in the nonideal layer are included in the dispersion relation. This unified theory can be applied to determine the stability of drift-resistive-inertial ballooning modes in the low temperature edge regions of tokamak and stellarator plasmas where steep density gradients exist.

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The Helically Symmetric Experiment, (HSX) Goals, Design and Status

Cited by 176 publications

References 3 publications

Effect of Quasihelical Symmetry on Trapped-Electron Mode Transport in the HSX Stellarator

Effect of Quasihelical Symmetry on Trapped-Electron Mode Transport in the HSX Stellarator

Experimental Evidence of Reduced Plasma Flow Damping with Quasisymmetry

Unified theory of resistive and inertial ballooning modes in three-dimensional configurations

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