Most importantly, the projections of fusion being 30 years away depended on assumptions about funding, when political considerations made it so that we basically never came anywhere close to those assumptions:
Fusion was never vaporware. We had developed working weapons relying on nuclear fusion in the 1950’s. Obviously using a full blown fission reaction to “ignite” the fusion reaction was never going to be practical, but the core physical principles were always known, with the need for the engineering and materials science to catch up with alternative methods of igniting and harvesting the energy from those fusion reactions.
But we never really devoted the resources to figuring it out. Only more recently has there been significant renewed interest in funding the research to make it possible, and as you note, many different projects are hitting different milestones on the frontier of that research.
Most importantly, the projections of fusion being 30 years away depended on assumptions about funding, when political considerations made it so that we basically never came anywhere close to those assumptions:
https://commons.wikimedia.org/wiki/File:U.S._historical_fusion_budget_vs._1976_ERDA_plan.png
Fusion was never vaporware. We had developed working weapons relying on nuclear fusion in the 1950’s. Obviously using a full blown fission reaction to “ignite” the fusion reaction was never going to be practical, but the core physical principles were always known, with the need for the engineering and materials science to catch up with alternative methods of igniting and harvesting the energy from those fusion reactions.
But we never really devoted the resources to figuring it out. Only more recently has there been significant renewed interest in funding the research to make it possible, and as you note, many different projects are hitting different milestones on the frontier of that research.