UKAEA Papers

"Optimization of JET-DT and ITER operation by developing an understanding of the role of low-Z impurity on the H-mode pedestal"

• C. Giroud
• N. Aiba
• F. Militello
• C. Challis
• A. Chankin
• B. Lomanowski
• D. Hatch
• J. Harrison
• D. Frigione
• D. Moulton
• S. Pamela
• F. Parra
• J. Parisi
• I. Putzai
• D. Refy
• S. Saarelma
• C. Stavrou
• B. Tal
• E. Belonohy
• S. Brezinsek
• S. Buller
• C. Bowman
• E. Delabie
• A. Field
• J. Fontdecaba
• A. Huber
• A. Meigs
• S. Menmuir
• J. Simpson
• JET Contributors

"The importance of the classical channel in the impurity transport of optimized stellarators"

• S. Buller
• A. Mollén
• S.L. Newton
• H.M. Smith
• I. Pusztai

In toroidal magnetic confinement devices, such as tokamaks and stellarators, neoclassical transport is usually an order of magnitude larger than its classical counterpart. However, when a high-collisionality species is present in an stellarator optimized for low Pfirsch-Schlüter current, its classical transport can be comparable to the neoclassica…

"Transport of collisional impurities with flux-surface density variation in stellarator plasmas"

• S. Buller
• H.M. Smith
• A. Mollen
• S.L. Newton
• I. Pusztai

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 expressions for the transport of a collisional impurity species with high-Z and flux-surface density-variation in t…

"Effects of flux-surface impurity density variation on collisional transport in stellarators"

• S. Buller
• H.M. Smith
• P. Helander
• A. Mollén
• S.L. Newton
• I. Pusztai

High-Z impurities in magnetic confinement devices are prone to develop density variations on the fluux-surface, which can significantly affect their transport. In this paper, we generalize earlier analytic stellarator calculations of the neoclassical radial impurity flux in the mixed-collisionality regime (collisional impurity and low-collisionalit…

"Neoclassical flows in deuterium-helium plasma density pedestals"

• P.M.S. Buller
• I. Pusztai
• S.L. Newton
• J.T. Omotani

In tokamak transport barriers, the radial scale of profile variations can be comparable to a typical ion orbit width, which makes the coupling of the distribution function across flux surfaces important in the collisional dynamics. We use the radially global steady-state neoclassical f code Perfect to calculate poloidal and toroidal flows, and radi…