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GEM is short for Gyrokinetic ElectroMagnetic. GEM is a gyrokinetic plasma turbulence simulation that uses the particle-in-cell method. It is used to study waves, instabilities and nonlinear behavior of tokamak fusion plasmas. Information about GEM can be found at the GEM web page. 〔(Plasma Simulation Group - Center for Integrated Plasma Studies )〕 There are two versions of GEM, one is a flux-tube version 〔A delta-f method for gyrokinetic simulations with kinetic electrons and electromagnetic perturbuations, Y. Chen and S. Parker, J. Comp. Phys. 189 463 (2003).〕 and the other one is a global general geometry version.〔Electromagnetic gyrokinetic delta-f particle-in-cell turbulence simulation with realistic equilibrium profiles and geometry, Y. Chen and S. Parker, J. of Comp. Phys. 220 839 (2007)〕 Both versions of GEM use a field-aligned coordinate system. Ions are treated kinetically, but averaged over their gyro-obits and electrons are treated as drift-kinetic. == The modeling of the tokamak plasmas== GEM solves the electromagnetic gyrokinetic equations which are the appropriate equations for well magnetized plasmas. The plasma is treated statistically as a kinetic distribution function. The distribution function depends on the three-dimensional position, the energy and magnetic moment. The time evolution of the distribution function is described by gyrokinetic theory which simply averages the Vlasov-Maxwell system of equations over the fast gyromotion associated with particles exhibiting cyclotron motion about the magnetic field lines. This eliminates fast time scales associated with the gyromotion and reduces the dimensionality of the problem from six down to five. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Gyrokinetic ElectroMagnetic」の詳細全文を読む スポンサード リンク
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