The stability and dynamics of Shear Alfvén modes in Tokamak equilibria characterized by non-monotonic q profiles is a relevant issue in the investigation of auxiliary-heated as well as ignited-plasma properties because of the role that such q profiles could play in obtaining improved confinement regimes. Two main elements could play a specific role in determining the Alfvén mode behaviour in th...

The δf particle-in-cell method for gyrokinetic simulations with kinetic electrons and electromagnetic perturbations [Y. Chen and S. Parker, J. Comput. Phys. 189 463 (2003)] is extended to include arbitrary toroidal equilibrium profiles and flux-surface shapes. The domain is an arbitrarily sized toroidal slice with periodicity assumed in toroidal direction. It is global radially and poloidally a...

Submitted for the APR09 Meeting of The American Physical Society Turbulent transport of trapped electron modes in collisionless magnetized plasma YONG XIAO, University of California, Irvine — A prominent candidate for the electron heat transport in high temperature toroidal plasmas is collisionless trapped electron mode (CTEM) turbulence. Our large scale simulations of CTEM turbulence using gyr...

Recent observations of giant flares from soft gamma-ray repeaters have exhibited multiple ∼ 25 − 150 Hz oscillations. Frequencies in this range are expected for toroidal shear waves in a neutron star (NS) crust, lending support to Duncan’s proposal that such modes may be excited in these events. This motivates a reassessment of how these waves reflect the NS structure and what role the magnetic...

Plasma toroidal rotation reduces reconnection of externally applied resonant magnetic perturbation (RMP) fields δB on rational (q = m/n) magnetic flux surfaces. Hence, it causes radial perturbations δBρm/n to be small there, and thus inhibits magnetic island formation and stochasticity in the edge of high (H-) mode confinement tokamak plasmas. However, electron collisional damping combined with...

The observed toroidal rotation in Alcator C-Mod Ohmic L-mode plasmas has been found to depend strongly on magnetic configuration. For standard discharges with a lower single null and the ion B rB drift downward, and with BT = 5.4 T, IP = 0.8 MA and ne = 1.4 10/m, the core toroidal rotation is measured to be in the range of 1020 km/s (counter-current). Similar plasmas with upper single null have...

The anomalously large thermal transport observed in tokamak experiments is the outstanding physics-based obstacle in the path to a commercially viable fusion reactor. Although decades of experimental and theoretical work indicate that anomalous transport and collective instabilities in the gyrokinetic regime are linked, no widely accepted description of this transport yet exists. Here, detailed...

The ideal MHD stability analysis of high-n (n is the toroidal mode number) Toroidal Alfvén Eigenmodes (TAE’s) is presented, using realistic and completely general ITER equilibria with shaped, up-down asymmetric, magnetic flux surfaces. An approach has been used, based on analytical-theoretical methods, which can give interesting results and allows us to analyze the conditions for enhanced TAE d...

discharges are carried out for the 15 MA high confinement mode ͑H-mode͒ scenario using PTRANSP, the predictive version of the TRANSP code. The thermal and toroidal momentum transport equations are evolved using turbulent and neoclassical transport models. A predictive model is used to compute the temperature and width of the H-mode pedestal. The ITER simulations are carried out for neutral beam i...

The density fluctuation of Geodesic Acoustic Mode (GAM) zonal flow has been observed in Ohmic deuterium plasma discharges with Langmuir probe arrays on the HL-2A tokamak. The density fluctuation has the poloidal mode number m < 1 and toroidal mode number n ~ 0. Its amplitude is consistent with theoretic prediction as well. Bispectral analysis shows that the nonlinear interaction between the GAM...