LPP presents at ICOPS

Lawrenceville Plasma Physics recently presented the results of their latest dense plasma focus experiments at the International Conference on Plasma Science (ICOPS).

The results include ion temperatures of 20-70 keV, record high fusion yield for a given current, and good agreement of the experiments with theory.

The theoretical model predicts that, in the range of peak currents explored so far by FF-1, ion temperatures will increase linearly with current, plasmoid density will scale as the square of current and plasmoid lifetime will scale linearly with current. Since fusion reaction rates go up as the square of the density and approximately the square of the temperature—in this temperature range—the model implies yield scales as current to the seventh power. That is exactly the scaling observed so far, and the absolute number of fusion reactions is just as predicted.

However, not all the results fit theory completely. For three of the four shots where the data is best, the ion energies were well above the predicted value—50-70 keV instead of the predicted value around 20 keV. On the other hand, the value of n^2V—the density squared times the volume—was about ten times less than predicted. So these plasmoids are hotter and either less dense or smaller than predicted. It is expected that newly functioning instruments will help sort this question out in the near future.

Another promising development is that other researchers at ICOPS reported high ion temperatures with pinch-type machines and this has added credibility to LPP’s claims.  The highest being 200 keV previously reported from the big Z-machine at Sandia National Laboratory.