Neutral beam driven impurity flow reversal in tokamaks

Stacey, Weston M.; Bennett, Richard M.; Sigmar, D. J.

doi:10.1016/0022-3115(84)90107-7

Cited by 3 publications

(6 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Experimentally, it has been observed in PLT [5,6] and ISX-B [7,8] that the central accumulation of edge-introduced impurities is much greater with counter-injection than with co-injection, in qualitative agreement with the more recent theory. Attempts [8,9] to quantitatively interpret some of the experimental results with earlier, incomplete versions [2,3] of the theory have been encouraging, although they have been unable to explain all features of both the co-injected and counter-injected results.…”

Section: Introductionmentioning

confidence: 98%

Rotation and impurity transport in a tokamak plasma with directed neutral-beam injection

et al. 1985

View full text Add to dashboard Cite

The authors have extended their previous collisional-regime theory for rotation and impurity transport in a tokamak plasma with strong, directed NBI and strong rotation (v^ « v th) to the plateau regime. The paper gives a summary of a kinetic theory derivation of the parallel viscous force in the strong rotation ordering and a self-consistent formalism for calculating ion and impurity rotation velocities and radial transport fluxes, as well as the radial electric field and the poloidal variation of the impurity density upon which the former strongly depend. Calculations for model problems representative of ISX-B and PLT are presented. The predicted impurity transport exhibits features that are in agreement with experimental observations.

show abstract

Section: Introductionmentioning

confidence: 98%

Rotation and impurity transport in a tokamak plasma with directed neutral-beam injection

et al. 1985

View full text Add to dashboard Cite

show abstract

“…With respect to the comparison of 'co' and 'counter' experiments, no significant difference was found in their global behaviour or in the transport of Al test impurities. This suggests that potential modifications of the impurity fluxes due to beam-driven toroidal rotation are negligible owing to the nearly perpendicular injection and to measured toroidal rotation velocities of < 2 X 10 s cnrs" 1 in the plasma centre, which are significantly lower than the thermal velocities of the intrinsic impurity ions [12,39,40].…”

Section: Results For Al Laser Blow-off Experimentsmentioning

confidence: 95%

Impurity transport in the wendelstein VII-A stellarator

Team¹,

Team²

1985

Nucl. Fusion

View full text Add to dashboard Cite

Impurity radiation losses in net-current-free neutral-beam-heated plasmas in the Wendelstein W VII-A stellarator are the combined effect of particularly strong impurity sources and improved particle confinement as compared with ohmically heated tokamak-like plasma discharges. Experiments are described and conclusions are drawn about the impurity species, their origin and their transport behaviour. The impurity transport is modelled by a 1-D impurity transport and radiation code. The evolution of the total radiation in time and space deduced from soft-X-ray and bolometer measurements can be fairly well simulated by the code. Experimentally, oxygen was found to make the main contribution to the radiation losses. In the calculations, an influx of cold oxygen desorbed from the walls of the order of 1013–1014 cm−2·s−1 and a rate of fast injected oxygen corresponding to a 1% impurity content of the neutral beams in combination with neoclassical impurity transport leads to quantitative agreement between the simulation and the observed radiation. The transport of Al trace impurities injected by the laser blow-off technique was experimentally studied by soft-X-ray measurements using a differential method allowing extraction of the time evolution of Al XII, XIII radial profiles. These are compared with code predictions, together with additional spectroscopic measurements. The main features of the impurity transport are consistent with neoclassical predictions, which explain particularly the central impurity accumulation. Some details, however, seem to require additional ‘anomalous’ transport. Such an enhancement is correlated with distortions of the magnetic configuration around resonant magnetic surfaces.

show abstract

“…Coming back to equation (10), we also consider the fast ions-impurity friction term T Z , which instead causes a radial inward convection of impurities. As noted in [15,16], the net convection caused by the combination of the term explicited in equation (11), and the frictional term T Z , depends on how much of the total torque is actually carried by the frictional term. A useful criterion is:…”

Section: Torque-driven Impurity Particle Fluxmentioning

confidence: 98%

“…Previous works have considered modifications to the species particle flux due to a direct effect of external sources of momentum [15][16][17][18] and a simplified model for the anomalous part of the stress tensor. The result found was that externally applied momentum injection could lead to a net outward impurity flux, under certain conditions.…”

Section: Introductionmentioning

confidence: 99%

“…The result found was that externally applied momentum injection could lead to a net outward impurity flux, under certain conditions. Application to the Princeton Large Torus (PLT) device in [16] shows that indeed the radial impurity flux can become outward at large injected neutral beam power. In this work, we employ a similar theoretical framework to compute the particle flux of an ion species, including the presence of an externally applied torque, e.g.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Impurity outward particle flux from externally applied torque

Fable,

Angioni

2023

Plasma Phys. Control. Fusion

View full text Add to dashboard Cite

In this work a term in the impurity particle flux expression, which arises from the externally applied angular momentum torque, is rederived and analyzed in detail. This contribution to the species particle flux is found to be directed outward for co-current injected torque in conditions pertinent to present devices, which could explain the increasing hollowness of light impurity density profiles observed experimentally as neutral beam injected power is increased. This result is obtained by revisiting the fluid framework to compute the particle flux of a generic ion species.

show abstract

Neutral beam driven impurity flow reversal in tokamaks

Cited by 3 publications

References 15 publications

Rotation and impurity transport in a tokamak plasma with directed neutral-beam injection

Rotation and impurity transport in a tokamak plasma with directed neutral-beam injection

Impurity transport in the wendelstein VII-A stellarator

Impurity outward particle flux from externally applied torque

Contact Info

Product

Resources

About