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dc.contributor.authorKaye, S. M.
dc.contributor.authorLeblanc, B. P.
dc.contributor.authorMazzucato, E.
dc.contributor.authorLee, K. C.
dc.contributor.authorDomier, C. W.
dc.contributor.authorSmith, D. R.
dc.contributor.authorYuh, H.
dc.contributor.authorRuiz Ruiz, Juan
dc.contributor.authorRen, Yang
dc.contributor.authorGuttenfelder, Walter
dc.contributor.authorWhite, Anne E.
dc.date.accessioned2017-05-08T17:41:30Z
dc.date.available2017-05-08T17:41:30Z
dc.date.issued2015-12
dc.date.submitted2015-08
dc.identifier.issn1070-664X
dc.identifier.issn1089-7674
dc.identifier.urihttp://hdl.handle.net/1721.1/108751
dc.description.abstractTheory and experiments have shown that electron temperature gradient (ETG) turbulence on the electron gyro-scale, k⊥ρe ≲ 1, can be responsible for anomalous electron thermal transport in NSTX. Electron scale (high-k) turbulence is diagnosed in NSTX with a high-k microwave scattering system [D. R. Smith et al., Rev. Sci. Instrum. 79, 123501 (2008)]. Here we report on stabilization effects of the electron density gradient on electron-scale density fluctuations in a set of neutral beam injection heated H-mode plasmas. We found that the absence of high-k density fluctuations from measurements is correlated with large equilibrium density gradient, which is shown to be consistent with linear stabilization of ETG modes due to the density gradient using the analytical ETG linear threshold in F. Jenko et al. [Phys. Plasmas 8, 4096 (2001)] and linear gyrokinetic simulations with GS2 [M. Kotschenreuther et al., Comput. Phys. Commun. 88, 128 (1995)]. We also found that the observed power of electron-scale turbulence (when it exists) is anti-correlated with the equilibrium density gradient, suggesting density gradient as a nonlinear stabilizing mechanism. Higher density gradients give rise to lower values of the plasma frame frequency, calculated based on the Doppler shift of the measured density fluctuations. Linear gyrokinetic simulations show that higher values of the electron density gradient reduce the value of the real frequency, in agreement with experimental observation. Nonlinear electron-scale gyrokinetic simulations show that high electron density gradient reduces electron heat flux and stiffness, and increases the ETG nonlinear threshold, consistent with experimental observations.en_US
dc.description.sponsorshipUnited States. Department of Energy (ontract No. DE-AC02- 09CH11466)en_US
dc.description.sponsorshipUnited States. Department of Energy. Office of Science (Contract No. DE-AC02-05CH11231)en_US
dc.language.isoen_US
dc.publisherAmerican Institute of Physics (AIP)en_US
dc.relation.isversionofhttp://dx.doi.org/10.1063/1.4936110en_US
dc.rightsArticle is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.en_US
dc.sourceProf. White via Chris Sherratten_US
dc.titleStabilization of electron-scale turbulence by electron density gradient in national spherical torus experimenten_US
dc.typeArticleen_US
dc.identifier.citationRuiz Ruiz, J., Y. Ren, W. Guttenfelder, A. E. White, S. M. Kaye, B. P. Leblanc, E. Mazzucato, et al. “Stabilization of Electron-Scale Turbulence by Electron Density Gradient in National Spherical Torus Experiment.” Physics of Plasmas 22, no. 12 (December 2015): 122501.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Aeronautics and Astronauticsen_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Nuclear Science and Engineeringen_US
dc.contributor.departmentMassachusetts Institute of Technology. Plasma Science and Fusion Centeren_US
dc.contributor.approverWhite, Anneen_US
dc.contributor.mitauthorRuiz Ruiz, Juan
dc.contributor.mitauthorRen, Yang
dc.contributor.mitauthorGuttenfelder, Walter
dc.contributor.mitauthorWhite, Anne E.
dc.relation.journalPhysics of Plasmasen_US
dc.eprint.versionFinal published versionen_US
dc.type.urihttp://purl.org/eprint/type/JournalArticleen_US
eprint.statushttp://purl.org/eprint/status/PeerRevieweden_US
dspace.orderedauthorsRuiz Ruiz, J.; Ren, Y.; Guttenfelder, W.; White, A. E.; Kaye, S. M.; Leblanc, B. P.; Mazzucato, E.; Lee, K. C.; Domier, C. W.; Smith, D. R.; Yuh, H.en_US
dspace.embargo.termsNen_US
dc.identifier.orcidhttps://orcid.org/0000-0003-4258-5273
dc.identifier.orcidhttps://orcid.org/0000-0003-2951-9749
mit.licensePUBLISHER_POLICYen_US


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