Nuclear fusion has the potential to secure the world’s future energy
requirements from the raw materials of seawater and lithium (one laptop
battery potentially has enough lithium to supply an adult with electricity
for 30 years) however engineering and scientific challenges still remain.
Turbulence and transport in the plasma limit the fusion reaction and are
difficult to study experimentally due to the extreme conditions in the
Tokamak (a toroidal vessel with magnetic coils).
Simulations are now providing a new tool for scientists and engineers
seeking to build and operate an efficient fusion power plant yet it is only
the current generation of supercomputers that are now capable of producing
detailed results.
We are focusing on CENTORI, a Fortran 90/95 simulation of a diffusive plasma
for plasma transport and turbulence studies, which uniquely can simulate the
whole of a Tokamak plasma with realistic geometry effects.
This allows physicists to study plasma effects at the macroscopic and
mesoscopic scales by averaging the microscopic properties of particles into
quantities like temperature, density and pressure. CENTORI has been designed
from the outset, by UKAEA: Fusion in Culham, to run on modern massively
parallel supercomputers and uses MPI for communication. It evolved from
Culham’s CUTIE, a highly successful serial turbulence and transport code.
EPCC and UKAEA: Fusion have a collaboration, which includes a PhD
studentship, working on further optimising CENTORI for current and
anticipated supercomputer architectures. Simulation campaigns have been
conducted on several high profile European HPC resources and are expected
to continue on a computer dedicated to the fusion community in Jülich.
Optimisation work has included analysing numerical algorithms and making
major changes the code’s memory structure to improve its serial performance
and to better employ SIMD floating point instructions whilst reducing the
size of messages passed over the network.
We present an overview of the possibilities of fusion power, the structure
and design of CENTORI as a modern world leading turbulence and transport
simulation and some ongoing and early results from the optimisation work
done to date.