Comment by kersplody

And even then, we are decades away from a commercial design due to the large number of engineering challenges needing to be solved. The next major milestone is getting a plasma gain of > 5, where helium-4 interactions become the dominant source of heating and dramatically change the behavior of the plasma. This has been simulated but never experimentally archived. Hopefully ITER will achieve this by 2030. Keep in mind that continuous operation with a Q plasma gain of at least 75 will be required for a commercially viable reactor. ITER will be lucky to hit 15 with upgrades through 2040.