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Title: Exploration of non-resonant divertor features on the Compact Toroidal Hybrid

Journal Article · · Nuclear Fusion

Abstract Non-resonant divertors (NRDs) separate the confined plasma from the surrounding plasma facing components (PFCs). The resulting striking field line intersection pattern on these PFCs is insensitive to plasma equilibrium effects. However, a complex scrape-off layer (SOL), created by chaotic magnetic topology in the plasma edge, connects the core plasma to the PFCs through varying magnetic flux tubes. The Compact Toroidal Hybrid (CTH) serves as a test-bed to study this by scanning across its inductive current. Simulations observe a significant change of the chaotic edge structure and an effective distance between the confined plasma and the instrumented wall targets. The intersection pattern is observed to be a narrow helical band, which we claim is a resilient strike line pattern. However, signatures of finger-like structures, defined as heteroclinic tangles in chaotic domains, within the plasma edge connect the island chains to this resilient pattern. The dominant connection length field lines intersecting the targets are observed via heat flux modeling with EMC3-EIRENE. At low inductive current levels, the excursion of the field lines resembles a limited plasma wall scenario. At high currents, a private flux region is created in the area where the helical strike line pattern splits into two bands. These bands are divertor legs with distinct SOL parallel particle flow channels. The results demonstrate the NRD strike line pattern resiliency within CTH, but also show the underlying chaotic edge structure determining if the configuration is diverted or limited. This work supports future design efforts for a mechanical structure for the NRD.

Sponsoring Organization:
USDOE
Grant/Contract Number:
FG02-00ER54610
OSTI ID:
2203576
Journal Information:
Nuclear Fusion, Journal Name: Nuclear Fusion Vol. 63 Journal Issue: 12; ISSN 0029-5515
Publisher:
IOP PublishingCopyright Statement
Country of Publication:
IAEA
Language:
English

References (47)

On mapping models of field lines in a stochastic magnetic field journal May 2004
First island divertor experiments on the W7-AS stellarator journal November 2001
Simulation of non-resonant stellarator divertor journal January 2020
Modelling of the magnetic field structures and first measurements of heat fluxes for TEXTOR-DED operation journal May 2004
Simulation of stellarator divertors journal September 2018
Initial Vacuum Magnetic Field Mapping in the Compact Toroidal Hybrid journal December 2006
Thirty years of turnstiles and transport journal September 2015
Quasi-helically symmetric toroidal stellarators journal May 1988
Minimum magnetic curvature for resilient divertors using Compact Toroidal Hybrid geometry journal March 2018
Resonant Pedestal Pressure Reduction Induced by a Thermal Transport Enhancement due to Stochastic Magnetic Boundary Layers in High Temperature Plasmas journal October 2009
EMC3-EIRENE simulation of first wall recycling fluxes in W7-X with relation to H-alpha measurements journal March 2021
Three-dimensional modeling of plasma edge transport and divertor fluxes during application of resonant magnetic perturbations on ITER journal May 2016
HSX as an example of a resilient non-resonant divertor journal March 2017
Change of the Magnetic-Field Topology by an Ergodic Divertor and the Effect on the Plasma Structure and Transport journal January 2006
Stellarator and tokamak plasmas: a comparison journal November 2012
Magnetic turnstiles in nonresonant stellarator divertor journal January 2022
Fractal structure of the magnetic field in the laminar zone of the Dynamic Ergodic Divertor of the Torus Experiment for Technology-Oriented Research (TEXTOR-94) journal June 2001
Performance of Wendelstein 7-X stellarator plasmas during the first divertor operation phase journal August 2019
Magnetic field line diversion in Helias stellarator configurations: perspectives for divertor operation journal May 1992
The EIRENE and B2-EIRENE Codes journal February 2005
Traces of stable and unstable manifolds in heat flux patterns journal April 2007
3D Edge Modeling and Island Divertor Physics journal April 2004
Identification and analysis of transport domains in the stochastic boundary of TEXTOR-DED for different mode spectra journal January 2008
Comparison of the influence of 2D and 3D geometry of the main chamber on plasma parameters in the SOL of ASDEX Upgrade journal December 2021
Review of magnetic islands from the divertor perspective and a simplified heat transport model for the island divertor journal November 2022
Aspects of three dimensional transport for ELM control experiments in ITER-similar shape plasmas at low collisionality in DIII-D journal November 2008
A new set of analytical formulae for the computation of the bootstrap current and the neoclassical conductivity in tokamaks journal February 2021
Transport in Hamiltonian systems journal August 1984
Volumetric recombination in EMC3-EIRENE: Implementation and first application to the pre-fusion power operation phase in ITER journal October 2021
Three-dimensional scrape off layer transport in the helically symmetric experiment HSX journal June 2016
Three-dimensional impurity transport modeling of neon-seeded and nitrogen-seeded LHD plasmas journal June 2018
Divertor concept for the W7-X stellarator and mode of operation journal May 2002
Optimization of quasi-symmetric stellarators with self-consistent bootstrap current and energetic particle confinement journal August 2022
Asymptotical and mapping methods in study of ergodic divertor magnetic field in a toroidal system journal January 1999
Design, Construction, and Operation of the Compact Toroidal Hybrid journal May 2017
MOMCON: A spectral code for obtaining three-dimensional magnetohydrodynamic equilibria journal February 1986
Stellarator design journal December 2015
Impact of screening of resonant magnetic perturbations in three dimensional edge plasma transport simulations for DIII-D journal May 2012
Impacts of resonant magnetic perturbations on edge carbon transport and emission on EAST with EMC3-EIRENE modelling journal May 2020
Experimental signatures of homoclinic tangles in poloidally diverted tokamaks journal January 2005
Interaction of stochastic boundary layer with plasma facing components journal June 1997
Design and Analysis of Divertor Scraper Elements for the W7-X Stellarator journal March 2014
First Application of 3D Peripheral Plasma Transport Code EMC3-EIRENE to Heliotron J journal September 2019
Understanding detachment of the W7-X island divertor journal June 2021
Determination of current and rotational transform profiles in a current-carrying stellarator using soft x-ray emissivity measurements journal January 2018
Theoretical and experimental investigations of stochastic boundaries in tokamaks journal October 1996
Two dimensional modelling approach to transport properties of the TEXTOR-DED laminar zone journal October 2000

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