Nuclear Fusion

Wendelstein Stellarator Plasma

By Steven J. Grisafi, PhD.

The fusion reactor in Greifswald, Germany has initiated its first plasma. Read the news report here.

Nuclear fusion is preferred over nuclear fission for producing steam to drive electric generators producing electricity because there is no hazardous waste. While producing electricity using nuclear fusion is straightforward conceptually, it remains a significant engineering challenge for constructing the enclosure of the plasma. Plasma is simply an ionized gas. But the temperatures required within the plasma to initiate the fusion of small nuclei, such as hydrogen or helium, are so great that they would melt the walls of any man-made enclosure the plasma comes into contact with. The solution, which had been proposed since the middle of the twentieth century, is to contain the plasma within magnetic fields preventing all contact of the ionized particles with the walls of the reactor. While conceptually simple, difficulty with the development of the magnetic field flux lines is such that the plasma particles cannot be contained within the magnetic fields for any appreciable length of time. The particles quickly fly off and collide with the walls.

Electrically charged particles that are accelerating radiate their own electromagnetic fields. The process of fusing small nuclei such as hydrogen and helium into larger nuclei is what powers our Sun. Since any curvilinear motion of electrically charged particles generates electromagnetic fields, the Sun becomes a giant magnet with magnetic field flux lines emanating both from it and then returning to it as the flux lines close upon themselves. Magnetic flux lines are always closed because magnetic monopoles do not exist. The magnetic field radiating forth from the Sun can interact with other electromagnetic particles. When astronomers observe the deflection of star light as it passes through the corona of the Sun during a solar eclipse, that star light feels an electromagnetic force upon it due to the magnetic field of the Sun. The electromagnetic force is many orders of magnitude stronger than the gravitational force. Newton’s Law of Gravity predicts a deflection of this star light. But the prediction is only approximately half of what astronomers observe. Einstein’s relativity theory predicts a deflection twice that of Newton’s Law.

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