An Introduction to Trinity

A fundamental challenge of fusion science is to maximize fusion power, which is determined primarily by macroscopic profiles of density and temperature. These profiles, which vary spatially on the system scale and evolve on the energy confinement time scale, drive turbulence at microscales in space and time. In the absence of MHD instability, this microturbulence is the dominant source of heat flux observed in standard tokamaks, which sets rigid constraints on the macroscopic proles. Consequently, it is of critical importance to understand the self-consistent interaction between the macroscopic profiles and the microturbulence.

The multiscale gyrokinetic transport code TRINITY was created to facilitate this understanding. It exploits the space and time scale separation between mean and fluctuation dynamics to solve for microturbulence on a fine space-time mesh embedded in a coarse space-time grid on which the mean plasma density, flow, and pressure are evolved. A more detailed description of the code is given at the TRINITY documentation website.