Modeling Kinetic Aspects of Global MHD Modes

Description and Aim

The fact that a tokamak plasma is almost collisionless poses intricate problems when one wants to combine a fluid description of the plasma like MHD with kinetic effects like parallel heat and particle transport,  or the interaction with energetic particles like fusion produced alpha’s and energetic electrons generated by radiofrequency (RF) current drive. The latter are inherently nonlocal.  A proper description of these nonlocal effects is essential when one wants to simulate, for example, the effect of RF current drive or the effect of fusion produced energetic alpha particles on global plasma waves and instabilities.

The more fundamental gyrokinetic description of the plasma provides a good model for the local ‘flux tube’ behavior of a collision less plasma and the small scale turbulence driving anomalous transport. However, the gyrokinetic description faces its own challenges with regard to the description of global waves and instabilities and the modeling of RF heating and current drive.

The goal of this meeting is to bring together experts from the different modeling communities (nonlinear MHD, gyrokinetic turbulence, and energetic particles and RF current drive) to discuss the problems faced by each of these communities. In particular the following questions will be addressed during the meeting:

1.    How can the kinetic aspects of parallel transport or RF current dive be modeled in a global nonlinear MHD simulation?

2.    In which ways can the interaction between fusion produced energetic alpha particles with global MHD modes be modeled in nonlinear magneto fluid simulations?

3.    How can nonlinear, global MHD instabilities be simulated with gyrokinetic codes?

4.    How can the effects of RF current drive and energetic ions be simulated in gyrokinetic turbulence codes?

5.    What can be learned from (local) gyrokinetic models for the inclusion of kinetic effects in (global) magneto fluid models?