2009
DOI: 10.1088/0029-5515/49/6/062002
|View full text |Cite
|
Sign up to set email alerts
|

Observation of an impurity hole in the Large Helical Device

Abstract: An extremely hollow profile of carbon impurity (denoted as an ‘impurity hole’) is observed associated with an increase in the ion temperature gradient after an impurity injection in the Large Helical Device. The central carbon density drops to 0.3% of the plasma density due to a strong outward convection driven by the ion temperature gradient, while an inward convection is predicted by neoclassical theory. Transport analysis gives a low diffusion coefficient of 0.4 m2 s−1 and an outward convection velocity of … Show more

Help me understand this report

Search citation statements

Order By: Relevance

Paper Sections

Select...
2
1

Citation Types

2
74
0

Year Published

2010
2010
2018
2018

Publication Types

Select...
8
1

Relationship

2
7

Authors

Journals

citations
Cited by 66 publications
(76 citation statements)
references
References 18 publications
2
74
0
Order By: Relevance
“…The positive-ion-based NBI (P-NBI) with low energy of 40 keV was perpendicularly injected with the port-through power of 6 MW for high power ion heating experiments [18,27]. In present experiment, ion temperature and rotation profiles are measured by charge exchange spectroscopy (CXS) system [28], and electric field can be observed by CXS only in periphery because of extremely hollowed impurity profile in ion ITB discharges [29]. In the core region, electrostatic potential profile/electric field is measured by heavy ion beam probe (HIBP) [30].…”
Section: Apparatusmentioning
confidence: 99%
“…The positive-ion-based NBI (P-NBI) with low energy of 40 keV was perpendicularly injected with the port-through power of 6 MW for high power ion heating experiments [18,27]. In present experiment, ion temperature and rotation profiles are measured by charge exchange spectroscopy (CXS) system [28], and electric field can be observed by CXS only in periphery because of extremely hollowed impurity profile in ion ITB discharges [29]. In the core region, electrostatic potential profile/electric field is measured by heavy ion beam probe (HIBP) [30].…”
Section: Apparatusmentioning
confidence: 99%
“…Nevertheless, the radial transport of impurities displays considerable complexity which often has eluded a theoretical explanation. Classical examples are the impurity screening shown by the High-Density H-mode observed in W7-AS [15] and the impurity hole in LHD plasmas [16]. The experimental validation of theoretical models of impurity density redistribution within a flux surface is of considerable importance as it provides some indirect validation of the model predictions on impurity radial transport [17].…”
Section: Introductionmentioning
confidence: 99%
“…In standard reactor-relevant conditions this accumulation is in most stellarators intrinsic to the lack of toroidal symmetry, that leads to the neoclassical electric field to point radially inwards. This statement, that the standard theory allows to formulate, has been contradicted by some experiments that showed weaker or no accumulation under such conditions [1,2]. The charge state of the impurities makes its transport more sensitive to the electric fields.…”
mentioning
confidence: 99%