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TJ-II:The influence of a core fast electron population on pellet fuelling efficiency in TJ-II: Difference between revisions
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TJ-II:The influence of a core fast electron population on pellet fuelling efficiency in TJ-II (view source)
Revision as of 17:27, 21 March 2018
, 21 March 2018→Description of the activity, including motivation/objectives and experience of the proponent (typically one-two pages)
(Created page with "== Experimental campaign == 2018 Spring == Proposal title == '''The influence of a core fast electron population on pellet fuelling efficiency in TJ-II''' == Name and affili...") |
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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)== | ||
The influence of fast electrons, that reside in the plasma core, on pellet ablation and fuelling efficiency is a topic that was recently highlighted in a work made on TJ-II.<ref>N. Panadero, et al, Nucl. Fusion 58 (2018) 026025.</ref> The work reported therein was part of the current effort to benchmark the pellet simulation code HPI2 for W7-X.<ref>F. Koechl F. et al, "Integrated modelling of pellet experiments at JET", Proc. 37th EPS Conf. on Plasma Physics (Dublin, 2010) 34A, O4.123</ref> It was found that simulations made using a stellarator-adapted version of the HPI2 code did not fully agree with experimental observations for plasmas with a significant population of fast electrons in the core. While the presence of such a population gives rise to local enhanced pellet ablation it also appears to modify the fast outwards drifting of pellet particles and thereafter particle deposition and fuelling efficiency.<ref>B. Pégourié, Plasma Phys. Control. Fusion 49 (2007) R87.</ref> Assuming that the fast electron population does not modify strongly the magnetic configuration it is hypothesized that this observation could be due to subtle modifications in the ablation phase, the deposition phase and/or the post-deposition transport phase of the pellet injection process. It is considered that the contribution of the first of these phases, i.e., ablation, may be minor, therefore it remains to closely evaluate the other two phases. In order to help understand this, it is intended to perform injections into #41777-like (with fast electrons) and # | The influence of fast electrons, that reside in the plasma core, on pellet ablation and fuelling efficiency is a topic that was recently highlighted in a work made on TJ-II.<ref>N. Panadero, et al, Nucl. Fusion 58 (2018) 026025.</ref> The work reported therein was part of the current effort to benchmark the pellet simulation code HPI2 for W7-X.<ref>F. Koechl F. et al, "Integrated modelling of pellet experiments at JET", Proc. 37th EPS Conf. on Plasma Physics (Dublin, 2010) 34A, O4.123</ref> It was found that simulations made using a stellarator-adapted version of the HPI2 code did not fully agree with experimental observations for plasmas with a significant population of fast electrons in the core. While the presence of such a population gives rise to local enhanced pellet ablation it also appears to modify the fast outwards drifting of pellet particles and thereafter particle deposition and fuelling efficiency.<ref>B. Pégourié, Plasma Phys. Control. Fusion 49 (2007) R87.</ref> Assuming that the fast electron population does not modify strongly the magnetic configuration it is hypothesized that this observation could be due to subtle modifications in the ablation phase, the deposition phase and/or the post-deposition transport phase of the pellet injection process. It is considered that the contribution of the first of these phases, i.e., ablation, may be minor, therefore it remains to closely evaluate the other two phases. In order to help understand this, it is intended to perform injections into #41777-like (with fast electrons) and #44614-like (no fast electrons) discharges to determine if the outward plasmoid drift significantly changes between these two scenarios. For this the fast-frame camera will be critical. The outcome of these experiments will be used to include a routine in the HPI2 code to account for such situations. For this, it will be attempted to simulate the fast-electron observations with the HPI2 code by modifying the contribution of the drift effect until agreement is reached. The stellarator-adapted version of HPI2 code for the W7-X was previously benchmarked on TJ-II.<ref>N. Panadero, et al, Nucl. Fusion 58 (2018) 026025.</ref> New routines will need similar benchmarking on the TJ-II. | ||
== If applicable, International or National funding project or entity == | == If applicable, International or National funding project or entity == | ||