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Island Divertor: Difference between revisions
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A particular feature of the island divertor topology is the existence of multiple, adjacent counter-streaming flow regions at the plasma edge<ref>[[doi:10.1088/1741-4326/ab4320|V. Perseo et al, Nucl. Fusion '''59''' (2019) 124003]]</ref>. Strong counter-streaming flows can lead to frictional dissipation of momentum, causing a reduction of the flow speed parallel to the magnetic field lines. This is likely to have played a role in substantial heat flux mitigation at the targets. | A particular feature of the island divertor topology is the existence of multiple, adjacent counter-streaming flow regions at the plasma edge<ref>[[doi:10.1088/1741-4326/ab4320|V. Perseo et al, Nucl. Fusion '''59''' (2019) 124003]]</ref>. Strong counter-streaming flows can lead to frictional dissipation of momentum, causing a reduction of the flow speed parallel to the magnetic field lines. This is likely to have played a role in substantial heat flux mitigation at the targets. | ||
Radiative power exhaust by impurity seeding was demonstrated | Radiative power exhaust by impurity seeding was demonstrated during the first island divertor experiments at the Wendelstein 7-X stellarator<ref>[[doi:10.1088/1741-4326/ab32c4|F. Effenberg et al, Nucl. Fusion '''59''' (2019) 106020]]</ref>. Stable plasma operation was shown during seeding with both neon (Ne) and nitrogen (N2). High radiative power losses (80%) were found to reduce the divertor heat loads globally by 2/3 with both seeding gases injected at a single toroidal location into one of five magnetic islands. | ||
The island divertor concept has | The island divertor concept has shown reliable heat flux control with hydrogen gas puffing and impurity seeding, making it a promising solution for future [[Detachment control|detachment control]] in high-performance scenarios and upgrades towards a metal divertor. Feedback-controlled divertor detachment has been achieved with hydrogen gas injection in W7-X<ref>[[doi:10.1016/j.nme.2023.101363|M. Krychowiak, et al, Nucl. Mater. Energy '''34''' (2023) 101363]]</ref> and may be extended to impurity seeding in the future. | ||
The edge magnetic structure in helically symmetric stellarators, such as the Helically Symmetric eXperiment (HSX) and Wendelstein 7X (W7-X), has been shown to have a significant impact on particle fueling and exhaust of the main plasma species (hydrogen) and impurity helium. The magnetic island chain in the plasma edge can control the plasma fueling from the recycling source and active gas injection, a basic requirement for a divertor system<ref>[[doi:10.1063/1.5026324|L. Stephey et al, Phys. Plasmas '''25''' (2018) 062501]]</ref>. | The edge magnetic structure in helically symmetric stellarators, such as the Helically Symmetric eXperiment (HSX) and Wendelstein 7X (W7-X), has been shown to have a significant impact on particle fueling and exhaust of the main plasma species (hydrogen) and impurity helium. The magnetic island chain in the plasma edge can control the plasma fueling from the recycling source and active gas injection, a basic requirement for a divertor system<ref>[[doi:10.1063/1.5026324|L. Stephey et al, Phys. Plasmas '''25''' (2018) 062501]]</ref>. | ||