{"id":{"repo_id":"mit","oai_identifier":"oai:dspace.mit.edu:1721.1/44766"},"canonical_url":"https://search.dev.ndltd.org/etd/mit/oai:dspace.mit.edu:1721.1/44766","repository":{"repo_id":"mit","name":"MIT","base_url":"https://dspace.mit.edu/oai/request"},"display":{"title":"Disruption mitigation and real-time detection of locked modes","abstract":"Disruptions are one of the largest problems facing tokamaks. In a large-scale experiment such as ITER, disruptions may cause crippling damage and severe setbacks in experimentation. One method for disruption mitigation involves the use of a gas jet which has been tested on both stable plasmas and vertical displacement events (VDEs) on Alcator C-Mod. In both cases, the jet was successful in mitigating disruption effects. The gas jet has not yet been tested on other types of disruptions. Locked-mode disruptions are easily created in C-Mod and could be used to test the effectiveness of the gas jet as a mitigation method if the jet could be fired early enough. It has been empirically observed that the electron cyclotron emissions (ECE) signal displays a flattening of the normally-present sawteeth before the current quench occurs in certain locked-mode disruptions. A procedure has been written which detects the ECE sawtooth suppression by calculating changes in the standard deviation of the signal over a moving time-window. This procedure has been programmed into the digital plasma control system (DPCS) for real-time testing. The procedure successfully located the locked modes present during a run.","abstract_html":"Disruptions are one of the largest problems facing tokamaks. In a large-scale experiment such as ITER, disruptions may cause crippling damage and severe setbacks in experimentation. One method for disruption mitigation involves the use of a gas jet which has been tested on both stable plasmas and vertical displacement events (VDEs) on Alcator C-Mod. In both cases, the jet was successful in mitigating disruption effects. The gas jet has not yet been tested on other types of disruptions. Locked-mode disruptions are easily created in C-Mod and could be used to test the effectiveness of the gas jet as a mitigation method if the jet could be fired early enough. It has been empirically observed that the electron cyclotron emissions (ECE) signal displays a flattening of the normally-present sawteeth before the current quench occurs in certain locked-mode disruptions. A procedure has been written which detects the ECE sawtooth suppression by calculating changes in the standard deviation of the signal over a moving time-window. This procedure has been programmed into the digital plasma control system (DPCS) for real-time testing. The procedure successfully located the locked modes present during a run.","abstract_has_math":false,"creators":["Angelini, Sarah Martha"],"institution":"Massachusetts Institute of Technology","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":"Massachusetts Institute of Technology. Dept. of Nuclear Science and Engineering.","school":null,"contributors":[],"advisors":["Robert S. Granetz."],"committee_chairs":[],"committee_members":[],"year":2008,"date_issued":"2008","date_published":"2008","updated_at":"2026-07-22T22:21:47Z","subjects":["Nuclear Science and Engineering."],"languages":["eng"],"rights":["M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission."],"rights_urls":["http://dspace.mit.edu/handle/1721.1/7582"],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/1721.1/44766","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Robert S. Granetz."]},{"key":"dc:contributor.department","label":"Department","values":["Massachusetts Institute of Technology. Dept. of Nuclear Science and Engineering."]},{"key":"dc:contributor.other","label":"Dc Contributor Other","values":["Massachusetts Institute of Technology. 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They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission."]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://dspace.mit.edu/handle/1721.1/7582"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/1721.1/44766"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2008.","Includes bibliographical references (p. 41)."]},{"key":"dc:description.abstract","label":"Abstract","values":["Disruptions are one of the largest problems facing tokamaks. In a large-scale experiment such as ITER, disruptions may cause crippling damage and severe setbacks in experimentation. One method for disruption mitigation involves the use of a gas jet which has been tested on both stable plasmas and vertical displacement events (VDEs) on Alcator C-Mod. In both cases, the jet was successful in mitigating disruption effects. The gas jet has not yet been tested on other types of disruptions. Locked-mode disruptions are easily created in C-Mod and could be used to test the effectiveness of the gas jet as a mitigation method if the jet could be fired early enough. It has been empirically observed that the electron cyclotron emissions (ECE) signal displays a flattening of the normally-present sawteeth before the current quench occurs in certain locked-mode disruptions. A procedure has been written which detects the ECE sawtooth suppression by calculating changes in the standard deviation of the signal over a moving time-window. This procedure has been programmed into the digital plasma control system (DPCS) for real-time testing. The procedure successfully located the locked modes present during a run."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["S.M."]},{"key":"dc:title","label":"Title","values":["Disruption mitigation and real-time detection of locked modes"]}]}],"canonical_facts":{"dc:contributor.advisor":["Robert S. Granetz."],"dc:contributor.department":["Massachusetts Institute of Technology. Dept. of Nuclear Science and Engineering."],"dc:contributor.other":["Massachusetts Institute of Technology. Dept. of Nuclear Science and Engineering."],"dc:creator":["Angelini, Sarah Martha"],"dc:date.accessioned":["2009-03-16T19:40:19Z"],"dc:date.available":["2009-03-16T19:40:19Z"],"dc:date.issued":["2008"],"dc:description":["Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2008.","Includes bibliographical references (p. 41)."],"dc:description.abstract":["Disruptions are one of the largest problems facing tokamaks. In a large-scale experiment such as ITER, disruptions may cause crippling damage and severe setbacks in experimentation. One method for disruption mitigation involves the use of a gas jet which has been tested on both stable plasmas and vertical displacement events (VDEs) on Alcator C-Mod. In both cases, the jet was successful in mitigating disruption effects. The gas jet has not yet been tested on other types of disruptions. Locked-mode disruptions are easily created in C-Mod and could be used to test the effectiveness of the gas jet as a mitigation method if the jet could be fired early enough. It has been empirically observed that the electron cyclotron emissions (ECE) signal displays a flattening of the normally-present sawteeth before the current quench occurs in certain locked-mode disruptions. A procedure has been written which detects the ECE sawtooth suppression by calculating changes in the standard deviation of the signal over a moving time-window. This procedure has been programmed into the digital plasma control system (DPCS) for real-time testing. The procedure successfully located the locked modes present during a run."],"dc:description.degree":["S.M."],"dc:identifier.uri":["http://hdl.handle.net/1721.1/44766"],"dc:language.iso":["eng"],"dc:publisher":["Massachusetts Institute of Technology"],"dc:rights":["M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission."],"dc:rights.uri":["http://dspace.mit.edu/handle/1721.1/7582"],"dc:subject":["Nuclear Science and Engineering."],"dc:title":["Disruption mitigation and real-time detection of locked modes"],"dc:type":["Thesis"]},"updated_at":"2026-07-22T22:21:47Z"}