We’re now over 30 shots and we have tripled fusion yield over last week. Not time yet to break out champagne, as we are still a factor of 4 short of our own record yield of ¼ joule. But going in the right direction. We’ve scanned from low to high fill pressure and we have found the sweet spot for now. Improvements are still needed. For one thing, #FF2B was making too much noise when it fired—from shorts or arcs somewhere outside the vacuum chamber.
We tracked them down and fixed them. Also, the appearance of the anode continues to evolve from shot to shot. After one shot, a horizontal line appeared on part of the anode, but then disappeared a couple of shots later. For symmetry the anode has to settle down to the same appearance—and thus the same smoothness—everywhere. This will take some time.
The image is the raw data from our Far Time of Flight detector (FTF) which shows the arrival of the X-ray peak (small peak at left) and the slower neutrons (big peak at right). Vertical scale is volts and horizontal is time in ns (billionths of a second). From shot 6, June 18. The height of the big peak at right is one way we know we have more fusion yield, as we are now working with deuterium, which produces neutrons from fusion reactions.