ITER 3D plasma simulation, with ripple contours. ITER is an international research project to develop a nuclear fusion reactor. This figure shows the ITER plasma surface (internal ring) and toroidal magnetic field coils (light blue loops). The colour-coded contours indicate local magnetic strength. The ripples in the contour lines are due to deviations from perfect symmetry due to the materials and equipment used. This simulation (an ITER Scenario 4 plasma) uses the VMEC 3D equilibrium code developed at Oak Ridge National Laboratory, Tennessee, USA. Image published in 2009.