LNF:Fuelling and Impurity Control Studies in the stellarators TJ-II and W7-X using Cryogenic Pellets and Tracer-Encapsulated Solid Pellets (TESPEL): Difference between revisions

LNF:Fuelling and Impurity Control Studies in the stellarators TJ-II and W7-X using Cryogenic Pellets and Tracer-Encapsulated Solid Pellets (TESPEL) (view source)

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 The goal of this project, which falls within the realm of magnetic confinement nuclear fusion, is to continue research initiated in projects ENE2013-48679-R and FIS2017-89326-R on fuelling and impurity control of plasmas in the stellarators TJ-II (Ciemat, Madrid) and W7-X (Greifswald, Germany). Further research to resolve these issues is critical to demonstrate steady-state operation of helical-type fusion reactors. Thus it will contribute to the development and scientific exploitation of stellarators, a priority highlighted in the document "Fusion Electricity: a roadmap to the realization of fusion energy" (EFDA 2012).
-The first tasks will be to investigate aspects of plasma fuelling that are still not fully understood and the effects of fuel pellets on plasma magnetic activity, plasma turbulence and plasma performance. For this, the medium-sized heliac TJ-II will be used. It is equipped with a cryogenic pellet injector (PI) for producing solid hydrogen pellets. It is intended to evaluate fuelling efficiency across a broad range of magnetic configurations and to identify and explore new pellet phenomena. While TJ-II is equipped with a large number of modern diagnostics, it is proposed to develop a new filterscope-based system to measure pellet cloud density and temperature to extend knowledge of pellet physics.
+The first aim is to investigate aspects of plasma fuelling that are still not fully understood and the effects of fuel pellets on plasma magnetic activity, plasma turbulence and plasma performance. For this, the medium-sized heliac TJ-II will be used. It is equipped with a cryogenic pellet injector (PI) for producing solid hydrogen pellets. It is intended to evaluate fuelling efficiency across a broad range of magnetic configurations and to identify and explore new pellet phenomena. While TJ-II is equipped with a large number of modern diagnostics, it is proposed to develop a new filterscope-based system to measure pellet cloud density and temperature to extend knowledge of pellet physics.
-The second aim is to continue to support impurity transport and accumulation studies in TJ-II and W7-X. In a trilateral collaboration with National Institute for Fusion Science (Japan) and IPP-Max-Planck (Greifswald, Germany), Tracer-Encapsulated Solid Pellet (TESPEL) injections systems have been installed on both TJ-II and W7-X. TESPEL are polystyrene speheres (diameter <1 mm) loaded with impurity tracers (elements other than fuel). This allows delivering a precise quantify of tracer to a preselected location in the plasma core. An important aspect of the collaboration was the establishment of a laboratory to fabricate TESPELs at Ciemat for both devices (FIS2017- 89326-R). Key parts of this proposal are to continue TESPEL fabrication at this laboratory, therby allowing Ciemat to maintain this fruitful collaboration, and to upgrade a vacuum ultraviolet spectrometer on TJ-II to provide important spectral line data for impurity identification in W7-X as well as in other fusion devices.
+The second aim is to continue to support impurity transport and accumulation studies in TJ-II and W7-X. In a trilateral collaboration with National Institute for Fusion Science (Japan) and IPP-Max-Planck (Greifswald, Germany), Tracer-Encapsulated Solid Pellet (TESPEL) injections systems have been installed on both TJ-II and W7-X. TESPELs are polystyrene spheres (diameter <1 mm) loaded with impurity tracers (elements other than fuel). This allows delivering a precise quantify of tracer to a preselected location in the plasma core. An important aspect of the collaboration has been the establishment of a laboratory to fabricate TESPELs at Ciemat for both devices (FIS2017- 89326-R). Key parts of this proposal are to continue TESPEL fabrication at this laboratory, thereby allowing Ciemat to maintain this fruitful collaboration, and to upgrade a vacuum ultraviolet spectrometer on TJ-II to provide important spectral line data for impurity identification in W7-X.
+The PI and TESPEL systems on TJ-II share a common injection guide lines. This unique set-up allows direct comparative studies of ablation, deposition and plasma response to be made thereby facilitating the understanding of common physics. Given that fuelling and impurity control are critical issues for stellarator steady-state operation, the project will allow us to continue to contribute to, and participate in, research programmes on W7-X, the stellarator of reference. Finally, team members have significant experience in the formation of young researchers at Master and PhD levels and in disseminating research to second level students and to the general public.
+== Main Results ==
-The PI and TESPEL systems on TJ-II share a common injection system and guide lines. This unique set-up allows direct compartive studies of ablation, deposition and plasma perturbation to be made thereby facilitating the understanding of common physics. Given that fuelling and impurity control are critical issues for stellarator steady-state operation, the project will allow LNF researchers to continue to contribute to, and participate in, research programmes on W7-X, the stellarator of reference. Finally, team members have significant experience in the formation of young researchers at Master and PhD levels and in disseminating research to second level students and to the general public.
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