Once you've picked values for the 3 sliders and pushed the START button, a short program computes the fusion power that would be produced in your reactor. Your score depends not only on the amount of fusion power, but also how much auxiliary power you had to use.

Several people have asked what the score really means. Reactor designers focus on a quantity they call Q, defined as the fusion power divided by the sum of the auxiliary and ohmic heating power. The ohmic heating power is the resistive heat generated by the tokamak's toroidal current and amounts to a few megawatts in this case. The problem with Q is that it can be very large (say, 1000) near ignition. Yet, values of 1 (breakeven) or 5 (plasma heating by alpha particles = external heating power) are interesting. Reactor designs with Q = 10 have been considered. To convey this fact to the user without going through all of the above explanation, we came up with the "score" = 100 ( Q / 100) 0.3, so that a score of 25 corresponds to Q = 1 and a score of 100 to Q = 100. Of course, scores greater than 100 are possible.

The picture in the middle represents a cut-away view of our Virtual Tokamak so we can see the plasma inside. Just for fun, this plasma changes color with your score according to the color scale at the bottom. A real fusion plasma wouldn't do this; it would always appear to be a sort of pink or red color.