Commun. Comput. Phys., 2 (2007), pp. 684-722. Fully Kinetic, Electromagnetic Particle-in-Cell Simulations of Plasma Microturbulence J. L. V. Lewandowski 1*, L. E. Zakharov 11 Plasma Physics Laboratory, Princeton University, P.O. Box 451, Princeton, NJ 08543, USA. Received 13 November 2006; Accepted (in revised version) 3 December 2006 Available online 15 January 2007 Abstract A novel numerical method, based on physical intuition, for particle-in-cell simulations of electromagnetic plasma microturbulence with fully kinetic ion and electron dynamics is presented. The method is based on the observation that, for low-frequency modes of interest [$\omega / {\omega}_{\mathrm{ci}} \ll 1$, $\omega$ is the typical mode frequency and ${\omega}_{ci}$ is the ion cyclotron frequency] the impact of particles that have velocities larger than the resonant velocity, $v_r \sim \omega / k_{\parallel}$ ($k_{\parallel}$ is the typical parallel wavenumber) is negligibly small (this is especially true for the electrons). Therefore it is natural to analytically segregate the electron response into an adiabatic response and a nonadiabatic response and to numerically resolve only the latter: this approach is termed the splitting scheme. However, the exact separation between adiabatic and nonadiabatic responses implies that a set of coupled, nonlinear elliptic equations has to be solved; in this paper an iterative technique based on the multigrid method is used to resolve the apparent numerical difficulty. It is shown that the splitting scheme allows for clean, noise-free simulations of electromagnetic drift waves and ion temperature gradient (ITG) modes. It is also shown that the advantage of noise-free kinetic simulations translates into better energy conservation properties. Notice: Undefined variable: ams in /var/www/html/issue/abstract/readabs.php on line 163 PACS: 52.35Kt, 52.30Jb, 52.35Ra Key words: Plasma micro-turbulence, particle-in-cell simulation, multigrid solver. *Corresponding author. Email: jlewando@pppl.gov (J. L. V. Lewandowski), zakharov@pppl.gov (L. E. Zakharov)