LNF:Estudios del confinamiento mejorado y de impurezas en los Stellarators TJ-II y W7-X mediante inyección de pastillas criogénicas (Pellets) y encapsulados de impurezas (TESPEL): Difference between revisions

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== Description of the project ==
== Description of the project ==
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 in plasmas created 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, in particular to identify operational scenarios that ensure adequate plasma fuelling and avoidance of impurity accumulation. This project 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).
1. The first aim is continue our research on plasma fuelling using cryogenic pellets. Many aspects related to the pellet ablation and to the effects of fuel pellets on plasma magnetic activity, plasma turbulence and plasma performance are still not fully understood. For this work, the medium-sized heliac TJ-II will be used. It is equipped with a cryogenic pellet injector (PI) for producing solid hydrogen pellets that can be injected at high velocity into the plasma from its outer plasma edge. In previous projects, it was found that a pellet injection enhances plasma performance significantly in the TJ-II (increased core density and ion temperature, higher stored energy, longer particle confinement, higher plasma beta). More recently, it was possible to reach record values for plasma performance using a train of such pellets. Understanding the physics behind such observations will be a key part of this project.
2. The second aim is to continue to support impurity transport and accumulation studies in TJ-II and W7-X. Under the umbrella of a trilateral collaboration (2020-2029) with the National Institute for Fusion Science (Japan) and IPP-Max-Planck (Greifswald, Germany), Tracer-Encapsulated Solid Pellet (TESPEL) injections systems are now operated on both TJ-II and W7-X. TESPELs are polystyrene spheres (diameter <1 mm) loaded with impurity tracers (atomic elements other than fuel). This allows delivering a precise quantify of tracer to a preselected location in the plasma core, after which its transport and confinement can be studied. An important aspect of the collaboration has been the establishment of a laboratory to fabricate TESPELs at Ciemat for both devices (project FIS2017- 89326-R). Key parts of this current project are to continue TESPEL fabrication for TJ-II and W7-X 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 aim of this project, which falls within the realm of magnetic confinement fusion, is to continue and broaden the research initiated in projects ENE2013-48679-R, FIS2017-89326-R and PID2020-116599RB-I00 on fuelling and impurity control in plasmas created in the stellarators TJ-II (Ciemat, Madrid), W7-X (Greifswald, Germany) and LHD (Toki, Japan). This research aims to investigate issues related to these two issue which are critical for achieving steady-state operation of helical-type fusion reactors. In particular, it is necessary to identify operational scenarios that ensure adequate plasma fuelling and short impurity confinement times, in particular, for heavy ions. It is intended that this work will support the European stellarator programme and 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 aim of this project, which falls within the realm of magnetic confinement fusion, is to continue and broaden the research initiated in projects ENE2013-48679-R, FIS2017-89326-R and PID2020-116599RB-I00 on fuelling and impurity control in plasmas created in the stellarators TJ-II (Ciemat, Madrid), W7-X (Greifswald, Germany) and LHD (Toki, Japan). This research aims to investigate issues related to these two issue which are critical for achieving steady-state operation of helical-type fusion reactors. In particular, it is necessary to identify operational scenarios that ensure adequate plasma fuelling and short impurity confinement times, in particular, for heavy ions. It is intended that this work will support the European stellarator programme and 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).
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