Performance at the double
Fusion experiments have kept pace with other hi-tech developments over the last 30 years. Since the early Russian T3 tokamak, the performance of fusion plasmas has doubled every 1.8 years (blue line). This compares with the doubling of the energy of particle accelerators every 3 years (green line), and the doubling of the number of transistors on a chip every 2 years (red line). The performance of fusion plasmas is defined in terms of the triple product, nτE (see text). The dashed line at the top shows the performance expected with ITER. (Courtesy of J B Lister.)