Performance and properties of the first plasmas of Wendelstein 7-X

Klinger, T.; Alonso, A.; Bozhenkov, S.; Burhenn, R.; Dinklage, A.; Fuchert, G.; Geiger, J.; Grulke, O.; Langenberg, A.; Hirsch, M.; Kocsis, G.; Knauer, J.; Krämer–Flecken, A.; Laqua, H. P.; Lazerson, S.; Landreman, Matt; Maaßberg, H.; Marsen, S.; Otte, M.; Pablant, N.; Pasch, E.; Rahbarnia, K.; Stange, T.; Szepesi, T.; Thomsen, H.; Traverso, P.; Velasco, J. L.; Wauters, T.; Weir, G.; Windisch, T.

doi:10.1088/0741-3335/59/1/014018

Cited by 121 publications

(137 citation statements)

References 18 publications

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“…and its impact on the impurity flux has received much attention lately. The recent work [6] summarizes most of what has been learnt by means of numerical simulations (experimental validation has been attempted in [17,18]) with the codes EUTERPE [5] and SFINCS [19]: the electrostatic potential was calculated for a series of devices (LHD [20], W7-X [21,22] and TJ-II [23]) and plasma profiles. The conclusion was that taking into account this effect changes quantitatively the impurity flux, but it remains negative, inward-directed, in most of the cases studied.…”

Section: Examplesmentioning

confidence: 99%

“…We have written a code, the KiNetic Orbit-averaging SOlver for Sellarators (KNOSOS), that solves equations (22) and (23), and we show in this paper first simulations of the electrostatic potential at low collisionalities including the superbanana-plateau contribution. Details of the code will be given elsewhere, and in this section we briefly discuss how the calculations are done with KNOSOS for the plasmas relevant for this paper.…”

Section: Knososmentioning

confidence: 99%

“…We first switch-off the tangential magnetic drift in equation (22), yielding it equivalent to equation (19): it can then solved without resorting to closeness to omnigeneity [27], and we use it for benchmarking KNOSOS against EUTERPE. Then we solve the complete equation (22) with KNOSOS: wherever the solutions are significantly different than those of equation (19), this will be an indication of the fact that the local approximation does not hold, and that radially global neoclassical simulations including the tangential magnetic drift might be needed for accurate results. The main conclusion of this part of the paper will be to show that this is the situation for LHD experimentally-relevant plasmas.…”

Section: Knososmentioning

confidence: 99%

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Large tangential electric fields in plasmas close to temperature screening

Velasco¹,

Calvo²,

García-Regaña³

et al. 2018

Plasma Phys. Control. Fusion

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Low-collisionality stellarator plasmas usually display a large negative radial electric field that has been expected to cause accumulation of impurities due to their high charge number. In this paper, two combined effects that can potentially modify this scenario are discussed. First, it is shown that, in low collisionality plasmas, the kinetic contribution of the electrons to the radial electric field can make it negative but small, bringing the plasma close to impurity temperature screening (i.e., to a situation in which the ion temperature gradient is the main drive of impurity transport and causes outward flux); in plasmas of very low collisionality, such as those of the Large Helical Device displaying impurity hole [1,2], screening may actually occur. Second, the component of the electric field that is tangent to the flux surface (in other words, the variation of the electrostatic potential on the flux surface), although smaller than the radial component, has recently been suggested to be an additional relevant drive for radial impurity transport. Here, it is explained that, especially when the radial electric field is small, the tangential magnetic drift has to be kept in order to correctly compute the tangential electric field, that can be larger than previously expected. This can have a strong impact on impurity transport, as we illustrate by means of simulations using the newly-developed code KNOSOS (KiNetic Orbit-averaging-SOlver for Stellarators).

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Section: Examplesmentioning

confidence: 99%

Section: Knososmentioning

confidence: 99%

Section: Knososmentioning

confidence: 99%

See 1 more Smart Citation

Large tangential electric fields in plasmas close to temperature screening

Velasco¹,

Calvo²,

García-Regaña³

et al. 2018

Plasma Phys. Control. Fusion

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“…• The use of electromagnetic forces to manipulate various forms of matter, including atoms [85][86][87] and fusion plasmas [88], is well established. The possibilities offered in such contexts by our unusual electromagnetic disturbances might be worthy of pursuit.…”

Section: Discussionmentioning

confidence: 99%

Monochromatic knots and other unusual electromagnetic disturbances: light localised in 3D

Cameron

2018

J. Phys. Commun.

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We introduce and examine a collection of unusual electromagnetic disturbances. Each of these is an exact, monochromatic solution of Maxwell's equations in free space with looped electric and magnetic field lines of finite extent and a localised appearance in all three spatial dimensions. Included are the first explicit examples of monochromatic electromagnetic knots. We also consider the generation of our unusual electromagnetic disturbances in the laboratory, at both low and high frequencies, and highlight possible directions for future research, including the use of unusual electromagnetic disturbances as the basis of a new form of three-dimensional display.

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“…W ENDELSTEIN 7-X (W7-X) is a large, superconducting stellarator with modular coils and an optimized magnetic field [1] [2].…”

Section: Introductionmentioning

confidence: 99%

Design of a High Resolution Probe Head for Electromagnetic Turbulence Investigations in W7-X

Agostinetti¹,

Spolaore²,

Brombin³

et al. 2018

IEEE Trans. Plasma Sci.

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An insertable probe head called High Resolution Probe (HRP) has been developed at Consorzio RFX in the framework of the EUROfusion S1 work program and in collaboration with IPP Greifswald, to study the electrostatic and electromagnetic features of turbulence in the edge region of Wendelstein 7-X using the Multi-Purpose Manipulator (MPM). The paper reports the design development of the HRP diagnostic head, from the choice of the sensors to the engineering design. The assumptions and evaluations supporting the main design choices, together with the R&D tests carried out to check the most critical parts, are described in detail.Index Terms-insertable probe, electromagnetic fluctuations, stellarator, W7-X

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Performance and properties of the first plasmas of Wendelstein 7-X

Cited by 121 publications

References 18 publications

Large tangential electric fields in plasmas close to temperature screening

Large tangential electric fields in plasmas close to temperature screening

Monochromatic knots and other unusual electromagnetic disturbances: light localised in 3D

Design of a High Resolution Probe Head for Electromagnetic Turbulence Investigations in W7-X

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