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TJ-II:Effect of pellet injection on the radial electric field profile of stellarators: Difference between revisions
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TJ-II:Effect of pellet injection on the radial electric field profile of stellarators (view source)
Revision as of 19:56, 24 January 2017
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== Proposal title == | == Proposal title == | ||
''Effect of pellet injection on the radial electric field profile of stellarators'' | ''Effect of pellet injection on the electron temperature profile and the radial electric field profile of stellarators'' | ||
== Name and affiliation of proponent == | == Name and affiliation of proponent == | ||
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== Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages)== | == Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages)== | ||
'''Motivation.''' | '''Motivation.''' | ||
Pellet injection modifies in a very abrupt manner the density and electron temperature profiles, see e.g. <ref>McCarthy 2016 IAEA/NF</ref>, and this is known to affect radial transport (at least transiently) in such a way that can be described by neoclassical theory, see e.g. <ref>Velasco 2016 PPCF</ref>. In particular, through modification of the density and electron temperature gradients, it can affect the radial electric field profile, which is set by ambipolarity of the neoclassical fluxes. Positive radial electric fields, connected to hollow density profiles, have been found in the Large Helical Device after injection of a pellet close to the edge <ref>Dinklage 2016 IAEA</ref>. This would be a manifestation of the well-known positive ion-root feature <ref>Baldzuhn 1999 PPCF</ref>. | Pellet injection modifies in a very abrupt manner the density and electron temperature profiles, see e.g. <ref>McCarthy 2016 IAEA/NF</ref>, and this is known to affect radial transport (at least transiently) in such a way that can be described by neoclassical theory, see e.g. <ref>Velasco 2016 PPCF</ref>. In particular, through modification of the density and electron temperature gradients, it can affect the radial electric field profile, which is set by ambipolarity of the neoclassical fluxes. Positive radial electric fields, connected to hollow density profiles, have been found in the Large Helical Device after injection of a pellet close to the edge <ref>Dinklage 2016 IAEA</ref>. This would be a manifestation of the well-known positive ion-root feature <ref>Baldzuhn 1999 PPCF</ref>. The evolution of the temperature profile is itself relevant, as pre-cooling with a pellet is thought to be a possible strategy for increasing the fuelling efficiency of pellets. We will characterise it and we will try to model it with neoclassical simulations. | ||
'''Objectives.''' | '''Objectives.''' | ||
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* Electrostatic potential. | * Electrostatic potential. | ||
The goal is to check whether the | The goal is to check whether the time evolution of the profiles is compliant with neoclassical predictions. | ||
== If applicable, International or National funding project or entity == | == If applicable, International or National funding project or entity == | ||