Estimation of Effective Momentum Diffusivity and Its Correlation with Neutral Particle Density Based on Toroidal Rotation Profiles in the TCABR TokamakShow others and affiliations
2025 (English)In: Brazilian journal of physics, ISSN 0103-9733, E-ISSN 1678-4448, Vol. 55, no 1, article id 43Article in journal (Refereed) Published
Abstract [en]
An equation for estimating the effective diffusivity χφeff based on the thermal and frictional forces arising from the interactions with neutral particles is provided. These interactions are primarily attributed to charge-exchange processes between ions and neutral particles. Our analysis indicates that the proposed forces are strong candidates to act as sources or sinks of momentum at the plasma edge. Furthermore, although we only have an estimated profile of neutral particles, the results demonstrate a strong dependence of the effective diffusivity on the ion-neutral collision frequency and a comparatively weaker dependence on ion temperature. We showed that the toroidal rotation profile in the TCABR tokamak is well described by the Helander model for toroidal rotation velocity in the Pfirsch-Schlüter regime, which depends on the ion temperature gradient in the presence of the neutral particles. The toroidal rotation profile has been reconstructed by a sum of Bessel functions, derived from the solution of a second-order differential equation for the toroidal velocity. In this initial study on momentum transport in TCABR, our findings indicate that χφeff—which accounts for both the diffusivity and pinch terms in the momentum equation—increases significantly in the outer plasma region. Additionally, it achieves a reasonable maximum value of approximately χφeff≈20 m2/s near the plasma edge at r/a≃0.87, in the same radial position of the maximum ion-neutral collision frequency, demonstrating that the applied method successfully captures the general behaviour of this component as reported in other works, and guiding future experimental validation.
Place, publisher, year, edition, pages
Springer Nature , 2025. Vol. 55, no 1, article id 43
Keywords [en]
Momentum transport, Nuclear fusion, Plasma rotation, Spectroscopy, Tokamak
National Category
Fusion, Plasma and Space Physics
Identifiers
URN: urn:nbn:se:kth:diva-358237DOI: 10.1007/s13538-024-01681-xISI: 001379740700003Scopus ID: 2-s2.0-85212757306OAI: oai:DiVA.org:kth-358237DiVA, id: diva2:1924871
Note
QC 20250114
2025-01-072025-01-072025-01-28Bibliographically approved