While LPPFusion’s experimental device, FF-1, remains inactive awaiting its new electrodes, a re-analysis of last year’s data shows that the electrons in the tiny plasmoid are just as hot as the ions—billions of degrees. This new analysis is important confirmation of the record 1.8 billion- degree ion temperatures published in 2012 and overcomes a limitation of that earlier data.
In that earlier paper, the mean ion energy was measured. But the measurement technique could not distinguish between ions moving as bulk motion around in a circle—trapped within the plasmoid—and random motion. It is the random motion that produces the collisions needed for fusion reactions. By analogy it is the difference between the ordered motion of cars circling a race track and the random motion of a pile-up. Collisions are bad in traffic—but good in fusion.
The new electron temperature analysis overcomes that limitation. The measurement is based on x-rays emitted when electrons collide with ions. So it only measures random, collision-generating motion. If the electrons have that much random motion, as these measurements show, then that confirms that the ion energy is also mostly random—good for producing fusion.
The x-ray data was obtained last year by filtering one detector with 3 mm of copper and another with 6 mm of copper. The more energetic the x-rays, the more would penetrate the full 6mm. So the energy of the x-rays could be measured by comparing the amount detected through the thick shield compared with those simultaneously detected through the thin shield. The more energetic the x-rays, the more energetic (hotter) the electrons that produced them.
Thanks to programming by our team’s Electrical Engineer Fred Van Roessel, we now have a program that automatically detects the x-ray peaks and lines them up in the two detectors (tricky because of the spikiness of the data). For 28 shots with clear matching of the peaks, the electron temperatures range from 90-160 keV (1.0 to 1.8 billion degrees K), just the same range as for the ion temperatures. Better yet, the electron temperature is correlated with the total fusion yield, as shown in Fig. 1. That indicates that we’re looking at the same plasmoid with both the x-ray and neutron detectors.
Figure 1. Fusion yield in billions of neutrons (from our deuterium experimental gas) is plotted against electron mean energy. The correlation indicates that both hot x-rays from the electrons and neutrons from fusion reactions are coming from the plasmoid and confirms the multi-billion-degree temperatures first reported in 2012. (100 keV energy is equivalent to 1.1 billion degrees K)
More work needs to be done before these results can be published. The ion and electron temperatures for individual shots must be compared as well as the times of the peak temperatures. But this work-in-progress is another piece of evidence that FF-1 has already achieved the temperatures needed for burning aneutronic fusion fuels.