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Bicoherence: Difference between revisions
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The two-dimensional bicoherence graph tends to show mainly two types of structures: | The two-dimensional bicoherence graph tends to show mainly two types of structures: | ||
* 'Points': indicating sharply defined, unchanging, locked frequencies. | * 'Points': indicating sharply defined, unchanging, locked frequencies. | ||
* 'Lines': these are more difficult to interpret. It is often stated that 'lines' are due to single mode (frequency) interacting with a broad range of frequencies (e.g., a [[Geodesic Acoustic Mode]] and broad-band turbulence<ref>Y. Nagashima et al, ''Observation of coherent bicoherence and biphase in potential fluctuations around geodesic acoustic mode frequency on JFT-2M'', [[doi:10.1088/0741-3335/48/5A/S38|Plasma Phys. Control. Fusion '''48''' (2006) A377]]</ref>) - but it is not evident that this is the only explanation. Particularly, two interacting oscillators (continuously exchanging energy) ''also'' produce lines in the bicoherence graph.<ref name="milligen1995"></ref><ref>B.Ph. van Milligen, L. García, B.A. Carreras, M.A. Pedrosa, C. Hidalgo, J.A. Alonso, T. Estrada and E. Ascasíbar, MHD mode activity and the velocity shear layer at TJ-II, [[doi:10.1088/0029-5515/52/1/013006|Nucl. Fusion 52 (2012) 013006]]</ref> | * 'Lines': these are more difficult to interpret. It is often stated that 'lines' are due to single mode (frequency) interacting with a broad range of frequencies (e.g., a [[Geodesic Acoustic Mode]] and broad-band turbulence<ref>Y. Nagashima et al, ''Observation of coherent bicoherence and biphase in potential fluctuations around geodesic acoustic mode frequency on JFT-2M'', [[doi:10.1088/0741-3335/48/5A/S38|Plasma Phys. Control. Fusion '''48''' (2006) A377]]</ref>) - but it is not evident that this is the only explanation. Particularly, two interacting oscillators (continuously exchanging energy) ''also'' produce lines in the bicoherence graph.<ref name="milligen1995"></ref><ref>B.Ph. van Milligen, L. García, B.A. Carreras, M.A. Pedrosa, C. Hidalgo, J.A. Alonso, T. Estrada and E. Ascasíbar, ''MHD mode activity and the velocity shear layer at TJ-II'', [[doi:10.1088/0029-5515/52/1/013006|Nucl. Fusion 52 (2012) 013006]]</ref> | ||
== Notes == | == Notes == | ||