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Non-linear dynamics of toroidicity-induced Alfvén eigenmodes on the National Spherical Torus Experiment

Abstract

The National Spherical Torus Experiment (NSTX, (Ono et al 2000 Nucl. Fusion 40 557)) routinely operates with neutral beam injection as the primary system for heating and current drive. The resulting fast ion population is super-Alfvénic, with velocities 1 < vfast/v Alfven < 5. This provides a strong drive for toroidicity-induced Alfvén eigenmodes (TAEs). As the discharge evolves, the fast ion population builds up and TAEs exhibit increasing bursts in amplitude and down-chirps in frequency, which eventually lead to a so-called TAE avalanche. Avalanches cause large (≲30%) fast ion losses over ∼1 ms, as inferred from the neutron rate. The increased fast ion losses correlate with a stronger activity in the TAE band. In addition, it is shown that a n = 1 mode with frequency well below the TAE gap appears in the Fourier spectrum of magnetic fluctuations as a result of non-linear mode coupling between TAEs during avalanche events. The non-linear coupling between modes, which leads to enhanced fast ion transport during avalanches, is investigated. © 2011 IAEA, Vienna.

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{"cc_re__cc_re__cc_by_4_0": ["arch/?q=author%3AKubota%2C%20S\">Kubota, S</a>; </li><li><a href=\"/search/?q=author%3ALeblanc%2C%20BP\">Leblanc, BP</a>; </li><li class=\"c-authorlist__end\"><a href=\"/search/?q=author%3AYuh%2C%20H\">Yuh, H</a> </li><li><a class=\"c-authorlist__list-more-link\">et al.</a></li></ul></div><div class=\"c-pubinfo\"><h2 class=\"c-pubinfo__location-heading\">Published Web Location</h2><a href=\"https://doi.org/10.1088/0029-5515/51/6/063035\" class=\"c-pubinfo__link\">https://doi.org/10.1088/0029-5515/51/6/063035</a><a href=\"https://creativecommons.org/licenses/by/4.0/\" class=\"c-pubinfo__license\"><img class=\"c-lazyimage\" data-src=\"/images/cc-by-large.svg\" alt=\"Creative Commons &#x27;BY&#x27; version 4.0 license\"/></a></div><div class=\"c-tabs\"><div class=\"c-tabs__tabs\"><button class=\"c-tabs__button-more\" aria-label=\"Show all tabs\">...</button><button class=\"c-tabs__button--active\">Main Content</button><button class=\"c-tabs__button\">Metrics</button><button class=\"c-tabs__button\">Author &amp; <!-- -->Article<!-- --> Info</button></div><div class=\"c-tabs__content\"><div class=\"c-tabcontent\"><"], "copyright__copyright__copyright": ["fluctuations as a result of non-linear mode coupling between TAEs during avalanche events. The non-linear coupling between modes, which leads to enhanced fast ion transport during avalanches, is investigated. \u00a9 2011 IAEA, Vienna.\n\nMany UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.\n\nMain Content\nFor improved accessibility of PDF content, download the file to your device.\nCurrent View", "fluctuations as a result of non-linear mode coupling between TAEs during avalanche events. The non-linear coupling between modes, which leads to enhanced fast ion transport during avalanches, is investigated. \u00a9 2011 IAEA, Vienna.\n\nMany UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.\n\nMain Content\nFor improved accessibility of PDF content, download the file to your device.\nCurrent View", "fluctuations as a result of non-linear mode coupling between TAEs during avalanche events. The non-linear coupling between modes, which leads to enhanced fast ion transport during avalanches, is investigated. \u00a9 2011 IAEA, Vienna.\n\nMany UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.\n\nMain Content\nFor improved accessibility of PDF content, download the file to your device.\nCurrent View", "fluctuations as a result of non-linear mode coupling between TAEs during avalanche events. The non-linear coupling between modes, which leads to enhanced fast ion transport during avalanches, is investigated. \u00a9 2011 IAEA, Vienna.\n\nMany UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.\n\nMain Content\nFor improved accessibility of PDF content, download the file to your device.\nCurrent View", "fluctuations as a result of non-linear mode coupling between TAEs during avalanche events. The non-linear coupling between modes, which leads to enhanced fast ion transport during avalanches, is investigated. \u00a9 2011 IAEA, Vienna.\n\nMany UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.\n\nMain Content\nFor improved accessibility of PDF content, download the file to your device.\nCurrent View", "fluctuations as a result of non-linear mode coupling between TAEs during avalanche events. The non-linear coupling between modes, which leads to enhanced fast ion transport during avalanches, is investigated. \u00a9 2011 IAEA, Vienna.\n\nMany UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.\n\nMain Content\nFor improved accessibility of PDF content, download the file to your device.\nCurrent View", "fluctuations as a result of non-linear mode coupling between TAEs during avalanche events. The non-linear coupling between modes, which leads to enhanced fast ion transport during avalanches, is investigated. \u00a9 2011 IAEA, Vienna.\n\nMany UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.\n\nMain Content\nFor improved accessibility of PDF content, download the file to your device.\nCurrent View", "fluctuations as a result of non-linear mode coupling between TAEs during avalanche events. The non-linear coupling between modes, which leads to enhanced fast ion transport during avalanches, is investigated. \u00a9 2011 IAEA, Vienna.\n\nMany UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.\n\nMain Content\nFor improved accessibility of PDF content, download the file to your device.\nCurrent View", "fluctuations as a result of non-linear mode coupling between TAEs during avalanche events. The non-linear coupling between modes, which leads to enhanced fast ion transport during avalanches, is investigated. \u00a9 2011 IAEA, Vienna.\n\nMany UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.\n\nMain Content\nFor improved accessibility of PDF content, download the file to your device.\nCurrent View", "fluctuations as a result of non-linear mode coupling between TAEs during avalanche events. The non-linear coupling between modes, which leads to enhanced fast ion transport during avalanches, is investigated. \u00a9 2011 IAEA, Vienna.\n\nMany UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.\n\nMain Content\nFor improved accessibility of PDF content, download the file to your device.\nCurrent View", "fluctuations as a result of non-linear mode coupling between TAEs during avalanche events. The non-linear coupling between modes, which leads to enhanced fast ion transport during avalanches, is investigated. \u00a9 2011 IAEA, Vienna.\n\nMany UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.\n\nMain Content\nFor improved accessibility of PDF content, download the file to your device.\nCurrent View", "fluctuations as a result of non-linear mode coupling between TAEs during avalanche events. The non-linear coupling between modes, which leads to enhanced fast ion transport during avalanches, is investigated. \u00a9 2011 IAEA, Vienna.\n\nMany UC-authored scholarly publications are freely available on this site because of the UC's open access policies. Let us know how this access is important for you.\n\nMain Content\nFor improved accessibility of PDF content, download the file to your device.\nCurrent View"]}