1,405 research outputs found
On the mutual effect of ion temperature gradient instabilities and impurity peaking in the reversed field pinch
The presence of impurities is considered in gyrokinetic calculations of ion
temperature gradient (ITG) instabilities and turbulence in the reversed field
pinch device RFX-mod. This device usually exhibits hollow Carbon/Oxygen
profiles, peaked in the outer core region. We describe the role of the
impurities in ITG mode destabilization, and analyze whether ITG turbulence is
compatible with their experimental gradients.Comment: 19 pages, 9 figures, accepted for publication in Plasma Phys.
Control. Fusio
Distractor Inhibition Predicts Individual Differences in the Attentional Blink
Background: The attentional blink (AB) refers to humans' impaired ability to detect the second of two targets (T2) in a rapid serial visual presentation (RSVP) stream of distractors if it appears within 200-600 ms of the first target (T1). Here we examined whether humans' ability to inhibit distractors in the RSVP stream is a key determinant of individual differences in T1 performance and AB magnitude
Validation of gyrokinetic modelling of light impurity transport including rotation in ASDEX Upgrade
Upgraded spectroscopic hardware and an improved impurity concentration
calculation allow accurate determination of boron density in the ASDEX Upgrade
tokamak. A database of boron measurements is compared to quasilinear and
nonlinear gyrokinetic simulations including Coriolis and centrifugal rotational
effects over a range of H-mode plasma regimes. The peaking of the measured
boron profiles shows a strong anti-correlation with the plasma rotation
gradient, via a relationship explained and reproduced by the theory. It is
demonstrated that the rotodiffusive impurity flux driven by the rotation
gradient is required for the modelling to reproduce the hollow boron profiles
at higher rotation gradients. The nonlinear simulations validate the
quasilinear approach, and, with the addition of perpendicular flow shear,
demonstrate that each symmetry breaking mechanism that causes momentum
transport also couples to rotodiffusion. At lower rotation gradients, the
parallel compressive convection is required to match the most peaked boron
profiles. The sensitivities of both datasets to possible errors is
investigated, and quantitative agreement is found within the estimated
uncertainties. The approach used can be considered a template for mitigating
uncertainty in quantitative comparisons between simulation and experiment.Comment: 19 pages, 11 figures, accepted in Nuclear Fusio
Low-Z impurity transport studies using CXRS at ASDEX Upgrade
EUROfusion Consortium 63305
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