{"id":188206,"date":"2024-04-27T00:29:58","date_gmt":"2024-04-27T05:29:58","guid":{"rendered":"https:\/\/lifeboat.com\/blog\/2024\/04\/time-resolved-biphase-signatures-of-quadratic-nonlinearity-observed-in-coupled-alfven-eigenmodes-on-the-diii-d-tokamak"},"modified":"2024-04-27T00:29:58","modified_gmt":"2024-04-27T05:29:58","slug":"time-resolved-biphase-signatures-of-quadratic-nonlinearity-observed-in-coupled-alfven-eigenmodes-on-the-diii-d-tokamak","status":"publish","type":"post","link":"https:\/\/lifeboat.com\/blog\/2024\/04\/time-resolved-biphase-signatures-of-quadratic-nonlinearity-observed-in-coupled-alfven-eigenmodes-on-the-diii-d-tokamak","title":{"rendered":"Time-resolved biphase signatures of quadratic nonlinearity observed in coupled Alfv\u00e9n eigenmodes on the DIII-D tokamak"},"content":{"rendered":"<p style=\"padding-right: 20px\"><a class=\"aligncenter blog-photo\" href=\"https:\/\/lifeboat.com\/blog.images\/time-resolved-biphase-signatures-of-quadratic-nonlinearity-observed-in-coupled-alfven-eigenmodes-on-the-diii-d-tokamak2.jpg\"><\/a><\/p>\n<p>In this study, we leverage wavelet-based bispectral analysis of magnetic fluctuation data to identify likely candidates for nonlinear three-wave coupling, which are subsequently investigated with bandpass filtering. The participating waves, two TAEs and a low-frequency magnetohydrodynamic (MHD) mode, are seen to satisfy coupling conditions in both frequency and toroidal wavenumber, consistent with nonlinear generation. We conclude that the detection of quadratic nonlinearities on sub-millisecond time scales is possible with this technique.<\/p>\n<p>The paper is organized as follows: Sec. <a href=\"https:\/\/pubs.aip.org\/aip\/pop\/article\/31\/4\/042305\/3283141\/Time-resolved-biphase-signatures-of-quadratic?searchresult=1#s2\" class=\"\">II<\/a> provides an overview of the relevant theory of TAE, while Sec. <a href=\"https:\/\/pubs.aip.org\/aip\/pop\/article\/31\/4\/042305\/3283141\/Time-resolved-biphase-signatures-of-quadratic?searchresult=1#s3\" class=\"\">III<\/a> contextualizes the experiment and describes its data. Section <a href=\"https:\/\/pubs.aip.org\/aip\/pop\/article\/31\/4\/042305\/3283141\/Time-resolved-biphase-signatures-of-quadratic?searchresult=1#s4\" class=\"\">IV<\/a> provides a primer on bicoherence analysis, in addition to simple examples of its implementation. Section <a href=\"https:\/\/pubs.aip.org\/aip\/pop\/article\/31\/4\/042305\/3283141\/Time-resolved-biphase-signatures-of-quadratic?searchresult=1#s5\" class=\"\">V<\/a> applies time-resolved bispectral analysis to the experimental data, focusing on the detection of quadratic nonlinearities. Section <a href=\"https:\/\/pubs.aip.org\/aip\/pop\/article\/31\/4\/042305\/3283141\/Time-resolved-biphase-signatures-of-quadratic?searchresult=1#s6\" class=\"\">VI<\/a> summarizes our work and considers the next steps of the analysis.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In this study, we leverage wavelet-based bispectral analysis of magnetic fluctuation data to identify likely candidates for nonlinear three-wave coupling, which are subsequently investigated with bandpass filtering. The participating waves, two TAEs and a low-frequency magnetohydrodynamic (MHD) mode, are seen to satisfy coupling conditions in both frequency and toroidal wavenumber, consistent with nonlinear generation. We [\u2026]<\/p>\n","protected":false},"author":427,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[20],"tags":[],"class_list":["post-188206","post","type-post","status-publish","format-standard","hentry","category-futurism"],"_links":{"self":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/188206","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/users\/427"}],"replies":[{"embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/comments?post=188206"}],"version-history":[{"count":0,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/posts\/188206\/revisions"}],"wp:attachment":[{"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/media?parent=188206"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/categories?post=188206"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lifeboat.com\/blog\/wp-json\/wp\/v2\/tags?post=188206"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}