D Tibbets wrote:5 milliseconds or more may be very significant, or not. For a Polywell operating at a density of 10^22 /M^3 it is impressive. But, I don't know at what density the Tri Alpha current efforts are working at. It is that old triple product consideration. Low Beta Tokamaks may manage 100s of seconds, but because of the lower density, the triple product is still a challenging goal.
I understand reverse field configurations may reach densities similar to Polywell goals, but I don't know how this relates to their current research, nor how confident they are of scaling projections for either density or temperature .9the other two legs of the triple product).
From what I understand, TAE are confident in being able to achieve the densities they need. What they are working on next is achieving the temperatures they need.
I had a chance to briefly interact with Sam Cohen about PPL's Direct Fusion Drive last year and from what I understood, their current reactor achieves (or should achieve that was not 100% clear), 50 ms pulse lengths at densities of 10^13 cm^-3 and 1 keV temperatures. It is my understanding that the 300 ms pulse(s) that Stephany Thomas mentioned at NIAC was indeed at a reduced density. Reactor requirements would be 3 million ms pulse length, 30 keV temperature and and 50 times the density.