It seems a bit unfair to think that the tokamak was selected without any competition or data on other concepts. Pinch based fusion concepts were in the works since the 1950’s but none panned out. Laser based fusion, colliding ion beam concepts and other ideas were examined before the tokamak was declared the winner. Admittedly, technology and modeling have come a long way since the tokamak was declared the most likely to succeed, but it wasn’t in the absence of other concepts.

Down-select is the natural process of technology development. You can’t run all the ponies forever. I think models like those developed by the semiconductor industry could successfully be applied to fusion. For the first period a pot of money is divided up among the candidates but all data is shared in the group. At the end of first period, the most promising concepts are chosen and funded as competitive entities with schedules, time lines, etc for some period. The winner, if you have one, becomes the focus for the last period until it is viable. I think the real threat of killing a project will help the teams focus on the real problems and not get caught up in side lights that seem to drag these projects off course. It might also encourage informed risk taking that is uncommon in the existing fusion programs.

The real problem is finding unbiased reviewers that can provide adequate technical assessment without being bound by political trappings. On might argue that ITER and NIF continue to exist as much due to their potential as capable marketing. I think the science of NIF is starting to win out over the marketing. ITER might lose out for budget reasons and a lack of a central bank account so where are we left? New diagnostics and side technologies were developed but we fell short of the goal. Key problems were identified that could hamper fusion in any form such as materials. Some information was gained which are goals of a science program but the energy program failed.