Topic/Type: 1.2 Fusion Plasmas (magnetic & inertial confinement), Oral

Global nonlinear particle-in-cell simulations of electromagnetic turbulence in tokamaks

A. Bottino1, B.D. Scott1, R. Hatzky2, S. Jolliet3, B.F. McMillan3, A.G. Peeters4, T.M. Tran3, T. Vernay3, L. Villard3

1 Max Planck Institut f?r Plasmaphysik, IPP-EURATOM Association, Garching, Germany
2 Computer Center of the Max-Planck-Gesellschaft, D-85748 Garching, Germany
3 CRPP, Association Euratom - Conf?d?ration Suisse, EPFL, Lausanne, Switzerland
4 CFSA, University of Warwick, CV4 7AL, Coventry UK

The ORB5 code [Jolliet S. et al. 2007 Comput. Phys. Commun.] is a global gyrokinetic PIC
turbulence simulation code which solves the set of gyrokinetic equations in the whole
plasma core down to the magnetic axis. A field-aligned filtering procedure and
sophisticated noise-control and heating operators [McMillan B.F. et al. 2008 Phys. Plasmas]
allow for accurate simulations with smaller numbers of markers as compared to standard PIC codes.
A newer version of ORB5 includes magnetic perturbations. The Amp?re\'s law
is solved iteratively using a control variates method solving the cancellation
problem of the unphysical adiabatic currents [R. Hatzky et al. 2007 J. Comp. Phys.].
The inclusion of magnetic perturbations allows for a comprehensive study of finite
effects on microinstability. The electromagnetic version of ORB5 has been tested in simpler
geometry and benchmarked against the linear electromagnetic code GYGLES.
The inclusion of the Amp?re\'s law does not degrade the scaling properties of ORB5,
since the field solver time is a small fraction of the total computational time.
The achievement of converged global electromagnetic simulations requires a
large amount of numerical resources: the Alfv?n dynamics and the kinetic
electrons impose strong constrains not only on the size of the time step
but also on the required spatial resolution. In this work we present the code benchmarks
and validations together with the first nonlinear results.