Actually that trillion dollar number was from a Tokamak researcher. Though I am not sure how serious they where being when using it. With Tokamak's Q isn't a

Actually that trillion dollar number was from a Tokamak researcher. Though I am not sure how serious they where being when using it. With Tokamak's Q isn't a constant for a general design it's a result of scaling laws and a specific size thus ITER was chosen at Q >= 10 but they could have picked bigger or smaller target. EX: https://nucleus.iaea.org/sites/fusionportal/Shared%20Documents/FEC%202016/fec2016-preprints/preprint0759.pdf https://nucleus.iaea.org/sites/fusionportal/Shared%20Documen... In 1997 JET hit an equivalent Q of 0.67 using a 3m by 1.25m device and D-T. You can look at costs and scaling factors along with the output of DD vs DT fusion. I took a trillion dollar budget just mean ~10,000x the cost of JET which seems to line up reasonably well. Though making such a large jump in scale would have it's own challenges.