Modular Stellarator Reactors and Plans for Wendelstein 7-X

Grieger, G.; Beidler, C. D.; Harmeyer, E.; Lotz, W.; Kißlinger, J.; Merkel, P.; Nührenberg, J.; Rau, F.; Strumberger, E.; Wobig, H.

doi:10.13182/fst92-a29977

Cited by 56 publications

(50 citation statements)

References 3 publications

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“…The final configuration investigated within the ICNTS is the Wendelstein 7-X (W7-X) device [70,71], which is currently under construction at IPP in Greifswald, Germany. This helias (helical-axis advanced stellarator) [72] emerged from an integrated design process which had the goal of finding magnetic fields which simultaneously fulfil a number of optimisation Contours have been plotted following the same scheme employed in Figure 1.…”

Section: Configurationsmentioning

confidence: 99%

Benchmarking of the mono-energetic transport coefficients—results from the International Collaboration on Neoclassical Transport in Stellarators (ICNTS)

et al. 2011

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Numerical results for the three mono-energetic transport coefficients required for a complete neoclassical description of stellarator plasmas have been benchmarked within an international collaboration. These transport coefficients are flux-surface-averaged moments of solutions to the linearised drift kinetic equation which have been determined using field-line-integration techniques, Monte Carlo simulations, a variational method employing Fourier-Legendre test functions and a finite difference scheme. The benchmarking has been successfully carried out for past, present and future devices which represent different optimisation strategies within the extensive configuration space available to stellarators.A qualitative comparison of the results with theoretical expectations for simple model fields is provided. The behaviour of the results for the mono-energetic radial and parallel transport coefficients can be largely understood from such theoretical considerations but the mono-energetic bootstrap current coefficient exhibits characteristics which have not been predicted.

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Section: Configurationsmentioning

confidence: 99%

Benchmarking of the mono-energetic transport coefficients—results from the International Collaboration on Neoclassical Transport in Stellarators (ICNTS)

et al. 2011

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“…The flow that arises in response to a parallel electric field is determined by the parallel momentum equation b· (43), where the parallel friction force F a again vanishes when only a single ion species is considered.…”

Section: Comparison Of Collision Operatorsmentioning

confidence: 99%

Comparison of particle trajectories and collision operators for collisional transport in nonaxisymmetric plasmas

et al. 2014

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In this work, we examine the validity of several common simplifying assumptions used in numerical neoclassical calculations for nonaxisymmetric plasmas, both by using a new continuum drift-kinetic code and by considering analytic properties of the kinetic equation. First, neoclassical phenomena are computed for the LHD and W7-X stellarators using several versions of the drift-kinetic equation, including the commonly used incompressible-E × B-drift approximation and two other variants, corresponding to different effective particle trajectories. It is found that for electric fields below roughly one third of the resonant value, the different formulations give nearly identical results, demonstrating the incompressible E ×B-drift approximation is quite accurate in this regime. However, near the electric field resonance, the models yield substantially different results. We also compare results for various collision operators, including the full linearized Fokker-Planck operator. At low collisionality, the radial transport driven by radial gradients is nearly identical for the different operators, while in other cases it is found to be important that collisions conserve momentum.

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“…One of the best new configurations is the helias (1), which was discovered by running the BETA code written at New York University (2). The Wendelstein 7-X (W7-X) experiment authorized for construction in Germany is one implementation of this concept (3). Another…”

Section: Introductionmentioning

confidence: 99%

Quasi-axially symmetric stellarators

Garabedian

1998

Proc. Natl. Acad. Sci. U.S.A.

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Confinement of a plasma for controlled thermonuclear fusion is studied numerically. Toroidal equilibria are considered, with an emphasis on the Modular Helias-like Heliac 2 (MHH2), which is a stellarator of low aspect ratio with just two field periods surrounded by 16 modular coils. The geometry is fully three-dimensional, but there is an axial symmetry of the magnetic structure that is calculated to give confinement competitive with that in circular tokamaks. Additional vertical and toroidal field coils, together with a current drive, provide the flexibility and the control of rotational transform necessary for a successful experiment. An MHH3 device with three field periods and comparable quasi-axial symmetry is presented, too, and because of reversed shear, its physical properties may be better. Variational analysis of equilibrium and stability is shown to give a more reliable prediction of performance for these stellarators than linearized or local theories that suffer from a failure of differentiability and convergence.

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Modular Stellarator Reactors and Plans for Wendelstein 7-X

Cited by 56 publications

References 3 publications

Benchmarking of the mono-energetic transport coefficients—results from the International Collaboration on Neoclassical Transport in Stellarators (ICNTS)

Benchmarking of the mono-energetic transport coefficients—results from the International Collaboration on Neoclassical Transport in Stellarators (ICNTS)

Comparison of particle trajectories and collision operators for collisional transport in nonaxisymmetric plasmas

Quasi-axially symmetric stellarators

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