2. Energetic Particle Group

Energetic particle group studies energetic particle physics in toroidal plamas via computer simulation. Important subjects of the simulation studies are; 1) energetic particle driven instabilities in LHD experiments such as Alfven eigenmodes, 2) energetic alpha particle behavior and neoclassical transport/ambipolar raidal electric field formation in burning plasmas, and 3) physics of self-organization and wave-particle interaction related to energetic particles. Simulation methods for prediction accuracy improvement and simulation time span extension are developed, and also the coordination with integrated transport codes is promoted.

Recent Research Results

Simulation of Alfven eigenmodes in ITER
The time evolution of Alfven eigenmodes in an ITER plasma was investigated using the MEGA code. The toroidal Alfven eigenmodes have the fastest growth rate at the initial phase shown in the left panel, while the beta-induced Alfven eigenmodes become dominant at the nonlinear phase shown in the right panel.

Introduction to simulation code

Name: MEGA
Purpose: simulation of energetic particle driven instabilities in toroidal plasmas
Algorithm: 4th order finite difference + 4th Runge-Kutta + PIC
Example: Linear properties and nonlinear frequency chirping of energetic-particle driven geodesic acoustic modes
(1) H. Wang and Y. Todo, Linear properties of energetic particle driven geodesic acoustic mode, Physics of Plasmas, Vol. 20 (2013) 012506-1 - 012506-8.
(2) H. Wang, Y. Todo, and C. C. Kim, Hole-clump pair creation in the evolution of energetic-particle-driven geodesic acoustic modes, Physical Review Letters, Vol. 110 (2013) 155006-1-155006-5.