Impurities in a non-axisymmetric plasma. Transport and effect on bootstrap current

Mollén, A.; Landreman, M.; Smith, H. M.; Braun, S.; Helander, P.

doi:10.1063/1.4935901

Impurities in a non-axisymmetric plasma. Transport and effect on bootstrap current

Journal Article · Fri Nov 20 00:00:00 EST 2015 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4935901· OSTI ID:1227103

^[1]; ^[2]; Smith, H. M. ^[3]; Braun, S. ^[4]; Helander, P. ^[3]

Chalmers Univ. of Technology, Goteborg (Sweden); Max-Planck-Institut fur Plasmaphysik, Greifswald (Germany); University of Maryland
Univ. of Maryland, College Park, MD (United States)
Max-Planck-Institut fur Plasmaphysik, Greifswald (Germany)
Max-Planck-Institut fur Plasmaphysik, Greifswald (Germany); Institute of Engineering Thermodynamics, Stuttgart (Germany)

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 solver, the SFINCS code (the Stellarator Fokker-Planck Iterative Neoclassical Conservative Solver) [M. Landreman et al., Phys. Plasmas 21 (2014) 042503] which employs the full linearized Fokker-Planck-Landau operator, to calculate neoclassical impurity transport coefficients for a Wendelstein 7-X (W7-X) magnetic configuration. We compare SFINCS calculations with theoretical asymptotes in the high collisionality limit. We observe and explain a 1/nu-scaling of the inter-species radial transport coefficient at low collisionality, arising due to the field term in the inter-species collision operator, and which is not found with simplified collision models even when momentum correction is applied. However, this type of scaling disappears if a radial electric field is present. We use SFINCS to analyze how the impurity content affects the neoclassical impurity dynamics and the bootstrap current. We show that a change in plasma effective charge Z_eff of order unity can affect the bootstrap current enough to cause a deviation in the divertor strike point locations.

View Accepted Manuscript (DOE)

Research Organization:: Univ. of Maryland, College Park, MD (United States)

Sponsoring Organization:: USDOE; USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)

Grant/Contract Number:: AC02-05CH11231; FC02-08ER54964; FG02-93ER54197

OSTI ID:: 1227103

Alternate ID(s):: OSTI ID: 1226677
OSTI ID: 22489842

Journal Information:: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 11 Vol. 22; ISSN PHPAEN; ISSN 1070-664X

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

References (24)

Effects of Net Currents on the Magnetic Configuration of W7-X Geiger, J.; Beidler, C. D.; Drevlak, M. Contributions to Plasma Physics, Vol. 50, Issue 8 https://doi.org/10.1002/ctpp.200900028	journal	July 2010
New velocity-space discretization for continuum kinetic calculations and Fokker–Planck collisions Landreman, Matt; Ernst, Darin R. Journal of Computational Physics, Vol. 243 https://doi.org/10.1016/j.jcp.2013.02.041	journal	June 2013
How to calculate the neoclassical viscosity, diffusion, and current coefficients in general toroidal plasmas Sugama, H.; Nishimura, S. Physics of Plasmas, Vol. 9, Issue 11 https://doi.org/10.1063/1.1512917	journal	November 2002
Observation of an impurity hole in a plasma with an ion internal transport barrier in the Large Helical Device Ida, K.; Yoshinuma, M.; Osakabe, M. Physics of Plasmas, Vol. 16, Issue 5 https://doi.org/10.1063/1.3111097	journal	May 2009
Momentum correction techniques for neoclassical transport in stellarators Maaßberg, H.; Beidler, C. D.; Turkin, Y. Physics of Plasmas, Vol. 16, Issue 7 https://doi.org/10.1063/1.3175328	journal	July 2009
Pfirsch–Schlüter impurity transport in stellarators Braun, S.; Helander, P. Physics of Plasmas, Vol. 17, Issue 7 https://doi.org/10.1063/1.3458901	journal	July 2010
Neoclassical transport simulations for stellarators Turkin, Y.; Beidler, C. D.; Maaßberg, H. Physics of Plasmas, Vol. 18, Issue 2 https://doi.org/10.1063/1.3553025	journal	February 2011
On the bootstrap current in stellarators and tokamaks Helander, P.; Geiger, J.; Maaßberg, H. Physics of Plasmas, Vol. 18, Issue 9 https://doi.org/10.1063/1.3633940	journal	September 2011
Comparison of particle trajectories and collision operators for collisional transport in nonaxisymmetric plasmas Landreman, M.; Smith, H. M.; Mollén, A. Physics of Plasmas, Vol. 21, Issue 4 https://doi.org/10.1063/1.4870077	journal	April 2014
Variational bounds for transport coefficients in three‐dimensional toroidal plasmas van Rij, W. I.; Hirshman, S. P. Physics of Fluids B: Plasma Physics, Vol. 1, Issue 3 https://doi.org/10.1063/1.859116	journal	March 1989
A method for calculating neoclassical transport coefficients with momentum conserving collision operator Taguchi, M. Physics of Fluids B: Plasma Physics, Vol. 4, Issue 11 https://doi.org/10.1063/1.860372	journal	November 1992
Plasma transport coefficients for nonsymmetric toroidal confinement systems Hirshman, S. P.; Shaing, K. C.; van Rij, W. I. Physics of Fluids, Vol. 29, Issue 9 https://doi.org/10.1063/1.865495	journal	September 1986
Observation of an impurity hole in the Large Helical Device Yoshinuma, M.; Ida, K.; Yokoyama, M. Nuclear Fusion, Vol. 49, Issue 6 https://doi.org/10.1088/0029-5515/49/6/062002	journal	May 2009
On impurity handling in high performance stellarator/heliotron plasmas Burhenn, R.; Feng, Y.; Ida, K. Nuclear Fusion, Vol. 49, Issue 6 https://doi.org/10.1088/0029-5515/49/6/065005	journal	April 2009
Benchmarking of the mono-energetic transport coefficients—results from the International Collaboration on Neoclassical Transport in Stellarators (ICNTS) Beidler, C. D.; Allmaier, K.; Isaev, M. Yu. Nuclear Fusion, Vol. 51, Issue 7 https://doi.org/10.1088/0029-5515/51/7/076001	journal	June 2011
Theory of plasma confinement in non-axisymmetric magnetic fields Helander, Per Reports on Progress in Physics, Vol. 77, Issue 8 https://doi.org/10.1088/0034-4885/77/8/087001	journal	July 2014
Local and global Fokker–Planck neoclassical calculations showing flow and bootstrap current modification in a pedestal Landreman, Matt; Ernst, Darin R. Plasma Physics and Controlled Fusion, Vol. 54, Issue 11 https://doi.org/10.1088/0741-3335/54/11/115006	journal	October 2012
Stellarator and tokamak plasmas: a comparison Helander, P.; Beidler, C. D.; Bird, T. M. Plasma Physics and Controlled Fusion, Vol. 54, Issue 12 https://doi.org/10.1088/0741-3335/54/12/124009	journal	November 2012
Aspects of steady-state operation of the Wendelstein 7-X stellarator Geiger, J.; Wolf, R. C.; Beidler, C. Plasma Physics and Controlled Fusion, Vol. 55, Issue 1 https://doi.org/10.1088/0741-3335/55/1/014006	journal	December 2012
On neoclassical impurity transport in stellarator geometry García-Regaña, J. M.; Kleiber, R.; Beidler, C. D. Plasma Physics and Controlled Fusion, Vol. 55, Issue 7 https://doi.org/10.1088/0741-3335/55/7/074008	journal	June 2013
On collisional impurity transport in nonaxisymmetric plasmas Mollén, A.; Landreman, M.; Smith, H. M. Journal of Physics: Conference Series, Vol. 561 https://doi.org/10.1088/1742-6596/561/1/012012	journal	November 2014
Fokker-Planck Equation for an Inverse-Square Force Rosenbluth, Marshall N.; MacDonald, William M.; Judd, David L. Physical Review, Vol. 107, Issue 1 https://doi.org/10.1103/PhysRev.107.1	journal	July 1957
New Advanced Operational Regime on the W7-AS Stellarator McCormick, K.; Grigull, P.; Burhenn, R. Physical Review Letters, Vol. 89, Issue 1 https://doi.org/10.1103/PhysRevLett.89.015001	journal	June 2002
Design and Analysis of Divertor Scraper Elements for the W7-X Stellarator Lore, Jeremy D.; Andreeva, Tamara; Boscary, Jean IEEE Transactions on Plasma Science, Vol. 42, Issue 3 https://doi.org/10.1109/TPS.2014.2303649	journal	March 2014

Cited By (6)

Stellarator Research Opportunities: A Report of the National Stellarator Coordinating Committee Gates, David A.; Anderson, David; Anderson, S. Journal of Fusion Energy, Vol. 37, Issue 1 https://doi.org/10.1007/s10894-018-0152-7	journal	February 2018
The importance of the classical channel in the impurity transport of optimized stellarators Buller, S.; Mollén, A.; Newton, S. L. Journal of Plasma Physics, Vol. 85, Issue 4 https://doi.org/10.1017/s002237781900045x	journal	July 2019
Flux-surface variations of the electrostatic potential in stellarators: impact on the radial electric field and neoclassical impurity transport Mollén, A.; Landreman, M.; Smith, H. M. Plasma Physics and Controlled Fusion, Vol. 60, Issue 8 https://doi.org/10.1088/1361-6587/aac700	journal	June 2018
Impact of main ion pressure anisotropy on stellarator impurity transport Calvo, Iván; Parra, Félix I.; Velasco, José Luis Nuclear Fusion, Vol. 60, Issue 1 https://doi.org/10.1088/1741-4326/ab581f	journal	December 2019
The importance of the classical channel in the impurity transport of optimized stellarators Buller, S.; Mollén, A.; Newton, S. L. arXiv https://doi.org/10.48550/arxiv.1903.12511	text	January 2019
Impact of main ion pressure anisotropy on stellarator impurity transport Calvo, Ivan; Parra, Felix I.; Velasco, J. L. arXiv https://doi.org/10.48550/arxiv.1907.08482	text	January 2019

Similar Records

Impurities in a non-axisymmetric plasma: Transport and effect on bootstrap current

Journal Article · Sat Nov 14 23:00:00 EST 2015 · Physics of Plasmas · OSTI ID:22489842

Flux-surface variations of the electrostatic potential in stellarators: impact on the radial electric field and neoclassical impurity transport

Journal Article · Sun Jun 10 20:00:00 EDT 2018 · Plasma Physics and Controlled Fusion · OSTI ID:1499870

Investigation of the neoclassical ambipolar electric field in ion-root plasmas on W7-X

Journal Article · Tue Jan 21 19:00:00 EST 2020 · Nuclear Fusion · OSTI ID:1595801

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Fokker Planck equation
Stellarators
electric fields
impurities
neoclassical transport
plasma impurities
plasma transport properties

Impurities in a non-axisymmetric plasma. Transport and effect on bootstrap current

Citation Formats

References (24)

Cited By (6)

Similar Records

Related Subjects