Related papers: Compressible impurity flow in the TJ-II stellarato…
Poloidal and toroidal velocities of fully-ionised carbon are measured by means of charge exchange recombination spectroscopy (CXRS) in the TJ-II stellarator. We present a detailed treatment of the 3D geometry and show that flow…
We review in a tutorial fashion some of the causes of impurity density variations along field lines and radial impurity transport in the moment approach framework. An explicit and compact form of the parallel inertia force valid for…
The accumulation of impurities in the core of magnetically confined plasmas, resulting from standard collisional transport mechanisms, is a known threat to their performance as fusion energy sources. Whilst the axisymmetric tokamak systems…
A burning fusion plasma has a large inwards flux of fuel and outwards flux of ash. Existing impurity transport theories do not account for a steady-state environment of such large fluxes. In this paper, we extend classical transport theory…
The assimilation of ablated high-Z impurities into the hot surrounding plasma along the magnetic field is investigated by first-principles kinetic simulations. It is found that the assimilated impurity ions, primarily driven by the…
Avoiding impurity accumulation is a requirement for steady-state stellarator operation. The accumulation of impurities can be heavily affected by variations in their density on the flux-surface. Using recently derived semi-analytic…
The drift kinetic equation is solved for low density TJ-II plasmas employing slowly varying, time-dependent profiles. This allows to simulate density ramp-up experiments and to describe from first principles the formation and physics of the…
A potential threat to the performance of magnetically confined fusion plasmas is the problem of impurity accumulation, which causes the concentration of highly charged impurity ions to rise uncontrollably in the center of the plasma and…
Impurity temperature screening is a favorable neoclassical phenomenon involving an outward radial flux of impurity ions from the core of fusion devices. Quasisymmetric magnetic fields are intrinsically ambipolar and give rise to temperature…
Long range correlations were measured using two remote reciprocating Langmuir probe systems at TJ-II. The influence of the rotational transform on the correlation was studied by scanning the magnetic configuration. A simple drift wave…
Plasma turbulence is studied using Doppler reflectometry at the TJ-II stellarator. By scanning the tilt angle of the probing beam, different values of the perpendicular wave numbers are probed at the reflection layer. In this way, the…
Turbulent transport of trace impurities impurities in the edge and scrape-off-layer of tokamak fusion plasmas is modelled by three dimensional electromagnetic gyrofluid computations including evolution of plasma profile gradients. The…
Main ions influence impurity dynamics through a variety of mechanisms; in particular, via impurity-ion collisions. To lowest order in an expansion in the main ion mass over the impurity mass, the impurity-ion collision operator only depends…
It has been theoretically predicted that the \ExB drift caused by the spontaneously generated potential in scrape-off-layers (SOLs) and divertors in tokamaks is of a similar size to the poloidal component of the parallel flow and turbulent…
The goal of this investigation is to study, in the line of previous works, the level of velocity fluctuations in different scenarios of the TJ-II stellarator. The method followed consists in measuring the apparent Doppler temperature of C4+…
Filaments/prominences are cold plasma (~ 10000 K) embedded in the solar corona, two orders of magnitude hotter. Filament plasma is structured by the magnetic field in thin elongated threads. Counter-streaming flows have been observed. The…
Impurities cause radiation losses and plasma dilution, and in stellarator plasmas the neoclassical ambipolar radial electric field is often unfavorable for avoiding strong impurity peaking. In this work we use a new continuum drift-kinetic…
In the pedestal of a tokamak, the sharp radial gradients of density and temperature can give rise to poloidal variation in the density of impurities. At the same time, the flow of the impurity species is modified relative to the…
High-Z impurities in magnetic confinement devices are prone to develop density variations on the flux-surface, which can significantly affect their transport. In this paper, we generalize earlier analytic stellarator calculations of the…
The anisotropic fluid equations governing a frictionless obliquely-flowing plasma around an essentially arbitrarily shaped three-dimensional ion-absorbing object in a strong magnetic field are solved analytically in the quasi-neutral…