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)

Revision as of 07:49, 5 September 2024

402 bytes removed , 5 September

→‎Description of the project

Kjm

207

edits

@@ Line 29: / Line 29: @@
 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 goal is to investigate some aspects of plasma fuelling that are still not fully understood (influence of fast electrons, magnetic configuration, and heating method on pellet ablation and deposition) as well as the effects of fuel pellets on plasma turbulence and magnetic activity. For this, the medium-sized heliac TJ-II will be used. It is equipped with a cryogenic pellet injector (PI) for fuelling with solid hydrogen. During previous projects it was found that fuelling efficiency is less that 30% for pellets reaching the centre but increases when fast electrons are present. In this project, it is intended to evaluate fuelling efficiency across a broad range of magnetic configurations and to explore some unexpected ablation phenomena observed in TJ-II, e.g. transitory increases in plasma core electron and ion temperatures and cold wave propogation ahead of injected pellets. 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 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 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.