Rotating Plasma Finding is Key for ITER
Key Challenges: Multiscale plasma simulation over the entire volume of a realistic tokamak device are possible only with petascale computing resources.
Why it Matters: Stabilization of tokamak plasma by external rotation sources has been demonstrated experimentally, but ITER is too large to have an external rotation source so it’s important to understand how to stabilize it via intrinsic rotation. Intrinisic rotation would help confine and stabilize the plasma and has been observed in multiple tokamaks but its origin is not well understood. ITER success may depend on how well the plasma can support rotation on its own.
Accomplishments: The SciDAC XGC1 gyrokinetic code was used to model relevant multi-scale physics over the entire plasma volume of the DIII-D fusion reactor. Findings point to the plasma edge as a source of rotation and strongly support the model of turbulence driven intrinsic torque as the origin of intrinsic rotation. The results suggest that ITER could achieve adequate spin up by utilizing this understanding.
NERSC Contribution: Simulations resulting in the publication below were performed on Hopper using over 10 million hours on about one-half of the system. It is one of several achievements made by this group in 2012 using NERSC resources. During AY2012, the repo consumed 78M hours (100% of allocation), running 22,200 jobs total, with 84% at concurrency of 16k cores or above and 48% at 64k or above.
Investigators: C. S. Chang (PPPL)
More Information: C.S. Chang, et al., “Physics of intrinsic rotation in flux-driven ITG turbulence,” Nucl. Fusion 52 (2012) 063013