NSE undergraduate Victoria Winters ’14 won one of three Undergraduate Poster Awards at the 54th Annual Meeting of the APS Division of Plasma Physics.
The award, given for research at the home insitution, recognizes Winters' research at Alcator C-Mod this past year as part of the MIT UROP program. Her winning poster, entitled "Exponential Spectra in Alcator C-Mod Edge Turbulence" was coauthored with Professor Anne White (MIT-PSFC), David Pace (General Atomics), Jim Terry, Arturo Dominguez, Professor Felix Parra and Jerry Hughes (MIT-PSFC).
The research proposes that exponential power spectra seen in edge turbulence of fusion plasmas is the result of deterministic chaos, and is associated with the presence of Lorentzian pulses in the time series data. Using reflectometer and Gas Puff Imaging (GPI) data in the Alcator C-Mod tokamak, the team analyzed exponential power spectra in Ohmic and L-mode plasmas. They found that both reflectometer homodyne signals and GPI signals measuring density fluctuations just inside or at the Last Closed Flux Surface (LCFS) exhibit exponential power spectra. Theoretically, the characteristic slope of the data on a semi-log plot gives the full width of the underlying Lorentzian pulses. Using a separate fitting routine, individual Lorentzian pulses in the reflectometer time series data have been identified, and the widths of the Lorentzian pulses match the inverse characteristic frequency of the exponential spectra. Preliminary analysis of the waiting times and pulse amplitudes indicate these are randomly distributed, yet the pulse widths have a narrow distribution. This is consistent with the deterministic chaos model, and further work is in progress to assess the robustness of the results.
Winters was also the recipient of the Department's 2012 Outstanding UROP Award for outstanding contributions to research in Nuclear Science & Engineering for her research on this same topic.
L to R: Prof. Cary Forest, University of Wisconsin, 2012 Chair of DPP, Victoria Winters, four other student award winners, Prof. Paul Miller of West Virginia University, the APS-DPP Sub-Committee Chair for Education and Outreach.