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Bruno Coppi and John Rice. Victora, Michelle (Michelle M.) Massachusetts Institute of Technology. Department of Physics. Massachusetts Institute of Technology. Department of Physics 2015-01-05T20:04:45Z 2015-01-05T20:04:45Z 2014 2014 http://hdl.handle.net/1721.1/92675 898190284 Thesis: S.B., Massachusetts Institute of Technology, Department of Physics, 2014. Cataloged from PDF version of thesis. Includes bibliographical references (pages 43-45). Using a spatially-resolving x-ray spectrometer system, the toroidal rotation velocity in Alcator C-Mod plasmas is measured and analyzed. At the L-H and L-I transition, there is a co-current movement in the toroidal rotation velocity.The propagation of this rotational velocity from the edge to the core of the torus was measured following the L- to H- and L- to I-mode transitions. A hyperbolic tangent fit was used to determine a single variable for rise time in rotational velocity. The hyperbolic tangent fit parameter acts as a proxy for the global momentum confinement time, which is then compared to other plasma parameters. Through this compaxison, we found an decrease in rise time in correlation with increasing density(n)/current(I), particularly distinctive in the range of 1-2.5 x 10²⁰ (MA x m³)-¹. Due to a lack of overlap in density between I- and H-mode, we find this may be indicative of an overall decrease in rise time between L- to I- and L- to H-mode transitions. In order to explore this possibility, we must achieve I-mode runs with the same current and density as Hmode to determine if there is still a decrease between the two transitions. by Michelle Victora. S.B. 45 pages eng Massachusetts Institute of Technology 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. http://dspace.mit.edu/handle/1721.1/7582 Physics. Global momentum confinement times in Alcator C-Mod H- and I- regime plasmas Thesis application/pdf false Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="d1571e9c-d2e3-47ef-a138-55ed0daea4c8"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Language>eng</Language> <Title>Global momentum confinement times in Alcator C-Mod H- and I- regime plasmas</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2014</PublicationDate> <Authors> <Author> <DisplayName>Victora, Michelle (Michelle M.)</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://dspace.mit.edu/handle/1721.1/7582</License> <Keyword>Physics.</Keyword> <Abstract>Using a spatially-resolving x-ray spectrometer system, the toroidal rotation velocity in Alcator C-Mod plasmas is measured and analyzed. At the L-H and L-I transition, there is a co-current movement in the toroidal rotation velocity.The propagation of this rotational velocity from the edge to the core of the torus was measured following the L- to H- and L- to I-mode transitions. A hyperbolic tangent fit was used to determine a single variable for rise time in rotational velocity. The hyperbolic tangent fit parameter acts as a proxy for the global momentum confinement time, which is then compared to other plasma parameters. Through this compaxison, we found an decrease in rise time in correlation with increasing density(n)/current(I), particularly distinctive in the range of 1-2.5 x 10²⁰ (MA x m³)-¹. Due to a lack of overlap in density between I- and H-mode, we find this may be indicative of an overall decrease in rise time between L- to I- and L- to H-mode transitions. In order to explore this possibility, we must achieve I-mode runs with the same current and density as Hmode to determine if there is still a decrease between the two transitions.</Abstract> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>