Department
Physics
Major
Physics and Nuclear Engineering
Research Advisor
Alexander, Ralph William, Jr.
Advisor's Department
Physics
Funding Source
DOE National Undergraduate Fellowship
Abstract
Linear stability diagrams are presented to clarify the onset of toroidal drift modes, including ITG, and resonant and non-resonant TEMs, as a function of density and temperature gradients. Nearly two thousand linear gyrokinetic stability analyses were performed with the GS2 code to generate a stability diagram, varying density and temperature gradients around the "Cyclone Base Case." A series of nonlinear gyrokinetic simulations have been carried out to analyze the anisotropy of the turbulent eddies, and the role of zonal flows, as a function of drive. Stronger zonal flows should on average reduce the anisotropy in the radial and poloidal wavenumber spectra. Our results show that the anisotropy depends on the type and strength of the drive. Two separate studies have previously found that zonal flows play very different roles in TEM turbulence. The first [1], found that zonal flows play a strong role near threshold, where they produce a nonlinear upshift. The second [2], for a case well above threshold, found that zonal flows have little effect on the turbulent saturation level.
[1] D.R. Ernst et al., Phys. Plasmas 11(5) (2004) 2637. Also, IAEA-CN-149/TH/1-3 (2006)
[2] T. Dannert et al., Phys. Plasmas 12 (2005) 072309
Biography
Michael Hoffman is a senior attending the Missouri University of Science and Technology majoring in Physics and Nuclear Engineering with a minor in Mathematics. He is the son of David Hoffman and Tonya Toebben and from Russellville, MO. He is an active member of the Society of Physics Students, American Nuclear Society and Missouri S& T Journal Club. Michael is currently involved in research and public outreach for science. Upon graduation, Michael is planning to pursue Ph.D. work in the area of plasma physics with application toward fusion energy.
Research Category
Natural Sciences
Presentation Type
Poster Presentation
Document Type
Poster
Award
Natural Sciences poster session, First place
Location
Havener Center, Upper Atrium/Hallway
Presentation Date
9 Apr 2008, 1:00 pm - 3:00 pm
Linear and nonlinear study of trapped electron mode turbulence
Havener Center, Upper Atrium/Hallway
Linear stability diagrams are presented to clarify the onset of toroidal drift modes, including ITG, and resonant and non-resonant TEMs, as a function of density and temperature gradients. Nearly two thousand linear gyrokinetic stability analyses were performed with the GS2 code to generate a stability diagram, varying density and temperature gradients around the "Cyclone Base Case." A series of nonlinear gyrokinetic simulations have been carried out to analyze the anisotropy of the turbulent eddies, and the role of zonal flows, as a function of drive. Stronger zonal flows should on average reduce the anisotropy in the radial and poloidal wavenumber spectra. Our results show that the anisotropy depends on the type and strength of the drive. Two separate studies have previously found that zonal flows play very different roles in TEM turbulence. The first [1], found that zonal flows play a strong role near threshold, where they produce a nonlinear upshift. The second [2], for a case well above threshold, found that zonal flows have little effect on the turbulent saturation level.
[1] D.R. Ernst et al., Phys. Plasmas 11(5) (2004) 2637. Also, IAEA-CN-149/TH/1-3 (2006)
[2] T. Dannert et al., Phys. Plasmas 12 (2005) 072309
