Electromagnetic Turbulence Simulations with Kinetic Electrons

NASA Astrophysics Data System (ADS)

Recently a new electromagnetic kinetic electron delta-f particle simulation model has been demonstrated to work well at large values of plasma beta times the ion-to-electron mass ratio [1,2]. The new simulation presented here uses a generalized split-weight scheme [3,4], where the adiabatic part is adjustable, along with a parallel canonical momentum formulation [5] and has been developed in three-dimensional toroidal flux-tube geometry. The model also includes electron-ion collisional effects and has been linearly benchmarked with continuum codes [6,7]. Electromagnetic simulations with kinetic electrons require a timestep approximately one-half that of electrostatic adiabatic electron simulations. Large box size simulations of 256 by 256 in units of ion gyroradius using a realistic mass ratios run well and detailed convergence studies have been done. Finite-beta reduction of energy transport, below the adiabatic electron level is observed for betas below the kinetic ballooning limit. For beta above the kinetic ballooning threshold fluxes are extremely high, and it is unlikely to be an experimentally relevant regime. Zonal flows with kinetic electrons are found to be turbulent with the spectrum peaking at zero and having a width in the frequency range of the driving turbulence. This is in contrast with adiabatic electron cases where the zonal flows are near stationary. We have shown that the linear behavior of the zonal flow is not significantly affected by kinetic electrons. Zonal fields [9] are found to be very weak consistent with theoretical predictions for betas below the kinetic ballooning limit. Detailed spectral and cross-correlation analysis of the turbulent spectra will be presented in the various limits. Acknowledgments: Thanks to A.M. Dimits, D. Shumaker, LLNL; V.K. Decyk, J.N. Leboeuf UCLA, work done using the Summit Framework and supported by the DOE SciDAC Plasma Microturbulence Project. [1] Y. Chen and S.E. Parker, to appear in J. Comput. Phys. (2003). [2] Y. Chen, S.E. Parker, B.I. Cohen, A.M. Dimits, W.M. Nevins, D. Shumaker, V.K. Decyk and J.N. Leboeuf, to appear in Nuc. Fusion (2003). [3] I. Manuilskiy and W.W. Lee, Phys. Plasmas 7 1381 (2000). [4] Y. Chen and S.E. Parker, Phys. Plasmas 8 2095 (2001) [5] T.S. Hahm, W.W. Lee and A. Brizard, Phys. Fluids 31 1940 (1988). [6] W. Dorland et. al, Proc. 18th Int. Conf. on Fusion Energy, IAEA, Sorrento, Italy, 2000; W. Dorland, F. Jenko, M. Kotschenreuther and B.N. Rogers, Phys. Rev. Lett. 85, 5336 (2000). [7] J. Candy and R. Waltz, to appear in J. Comput. Physics (2003). [8] A.V. Gruzinov and P.H. Diamond, Phys. Plasmas 3 1854 (1996), L. Chen, Z. Lin R.B. White and F. Zonca, Nuc. Fusion 41 747 (2001); P.N. Gudzar, R.G. Kleva, A. Das and P.K. Kaw, Phys. Plasmas 8 3907 (2001).

Parker, Scott E.

2003-10-01