Experimental studies and simulations of hydrogen pellet ablation in the stellarator TJ-II

Panadero, N.; McCarthy, K. J.; Koechl, F.; Baldzuhn, J.; Velasco, J. L.; Combs, S. K.; de la Cal, E.; García, R.; Hernández Sánchez, J.; Silvagni, D.; Turkin, Y.

doi:10.1088/1741-4326/aa9f8a

Title: Experimental studies and simulations of hydrogen pellet ablation in the stellarator TJ-II

Journal Article · Fri Jan 05 00:00:00 EST 2018 · Nuclear Fusion

DOI:https://doi.org/10.1088/1741-4326/aa9f8a· OSTI ID:1843726

Panadero, N. ^[1]; McCarthy, K. J. ^[1]; Koechl, F. ^[2]; Baldzuhn, J. ^[3]; Velasco, J. L. ^[1];

^[4]; de la Cal, E. ^[1]; García, R. ^[1]; Hernández Sánchez, J. ^[1]; Silvagni, D. ^[5]; Turkin, Y. ^[3]

Research Centre for Energy, Environment and Technology (CIEMAT), Madrid (Spain). Lab. Nacional de Fusión
Technische Univ. Wien (Austria). Atominstitut; Culham Science Centre, Abingdon (United Kingdom). Culham Centre for Fusion Energy (CCFE), EURATOM/UKAEA Fusion Association
Max Planck Institute for Plasma Physics, Greifswald (Germany)
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Univ. Carlos III de Madrid, Leganés (Spain)

Plasma core fuelling is a key issue for the development of steady-state scenarios in large magnetically-confined fusion devices, in particular for helical-type machines. At present, cryogenic pellet injection is the most promising technique for efficient fuelling. Here, pellet ablation and fuelling efficiency experiments, using a compact pellet injector, are carried out in electron cyclotron resonance and neutral beam injection heated plasmas of the stellarator TJ-II. Ablation profiles are reconstructed from light emissions collected by silicon photodiodes and a fast-frame camera system, under the assumptions that such emissions are loosely related to the ablation rate and that pellet radial acceleration is negligible. In addition, pellet particle deposition and fuelling efficiency are determined using density profiles provided by a Thomson scattering system. Furthermore, experimental results are compared with ablation and deposition profiles provided by the HPI2 pellet code, which is adapted here for the stellarators Wendelstein 7-X (W7-X) and TJ-II. Finally, the HPI2 code is used to simulate ablation and deposition profiles for pellets of different sizes and velocities injected into relevant W7-X plasma scenarios, while estimating the plasmoid drift and the fuelling efficiency of injections made from two W7-X ports.

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Research Organization:: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Sponsoring Organization:: USDOE; Ministry of Economic Affairs and Digital Transformation of Spain (MINECO); EUROfusion Consortium

Contributing Organization:: W7-X Team; TJ-II Team

Grant/Contract Number:: AC05-00OR22725; 633053; ENE2013- 48679-R; ENE2015-70142-P

OSTI ID:: 1843726

Journal Information:: Nuclear Fusion, Vol. 58, Issue 2; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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Pellet fueling experiments in Wendelstein 7-X Baldzuhn, J.; Damm, H.; Beidler, C. D. Plasma Physics and Controlled Fusion, Vol. 61, Issue 9 https://doi.org/10.1088/1361-6587/ab3567	journal	August 2019
Overview of recent TJ-II stellarator results Ascasíbar, E.; Alba, D.; Alegre, D. Nuclear Fusion, Vol. 59, Issue 11 https://doi.org/10.1088/1741-4326/ab205e	journal	July 2019
High-density experiments with hydrogen ice pellet injection and analysis of pellet penetration depth in Heliotron J Motojima, G.; Okada, H.; Okazaki, H. Plasma Physics and Controlled Fusion, Vol. 61, Issue 7 https://doi.org/10.1088/1361-6587/ab1d40	journal	June 2019
The impact of fast electrons on pellet injection in the stellarator TJ-II McCarthy, K. J.; Panadero, N.; Combs, S. K. Plasma Physics and Controlled Fusion, Vol. 61, Issue 1 https://doi.org/10.1088/1361-6587/aae038	journal	November 2018

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