Increasing the density of the plasmoid is the “long pole” in our fusion tent—what we need to do to get to net energy production. We know we must increase density a long way from our current results. But now it seems the goal post have moved somewhat nearer. New theoretical calculations indicate that an effect that was left out of previous calculation increases the fusion reaction rate at high magnetic fields and thus requires only about one third the plasma density we previously calculated. This reduces the improvement needed in density from about 10,000-fold to about 3,000-fold.
The new calculation is again based on the quantum magnetic field effect that LPP Chief Scientist Eric Lerner first applied to the dense plasma focus in 2003. This effect causes ions—nuclei—moving in extremely strong magnetic fields to transfer energy slowly to electrons. Back in 2003, we realized that this would keep the electrons cooler, so they would radiate less x-ray energy, making it easier to achieve the extremely high temperature needed for hydrogen-boron fusion. But until recently, we overlooked another beneficial effect.
In a typical plasma at low magnetic field, the nuclei move almost randomly on the microscopic level, so when two nuclei collide only about one third of their energy is directed along the line that connects them. But recently, we realized that at very high magnetic fields, the situation is different. The nuclei in that case are moving almost exactly along the direction of the magnetic fields. So when they collide head-on, their full energy goes into the collision. Since the fusion reaction rate rise with energy, up to a very high energy, the more-head on collisions speed up the reactions for a given density. Equally, they allow the same reaction rate at a lower plasma density.
The reason this alignment along the magnetic field line happens at very high magnetic fields is because the quantum magnetic field effect operates only for ions moving in the same direction as the electrons—along the field lines. If the ions randomly move across the field lines, they lose energy much more rapidly to the electrons, forcing the ions back onto the field lines. Thus the electrons, through the quantum effect, act as sheep dogs, herding the ions in the magnetic field direction, where they collide with each other head-on.
The result is to allow us to reach net energy production with somewhat less demanding density conditions—making our path shorter and easier. We’ll be publishing a paper on this in the coming months.
This news item was part of LPP’s July 15th, 2013 Focus Fusion report. See full report.