There is a patent (7180242) issued in 2007 for Tri-Alpha Energy's field reversed configuration nuclear fusion.
(H/T to Torulf2 at Talk Polywell)
There is another 31 page patent application US20100002823. (Controlled Fusion is a Field Reversed Configuration and Direct Energy Conversion.) Filed in 2009.
Formation of a field reversed configuration for magnetic and electrostatic confinement of plasma
A system and method for containing plasma and forming a Field Reversed Configuration (FRC) magnetic topology are described in which plasma ions are contained magnetically in stable, non-adiabatic orbits in the FRC. Further, the electrons are contained electrostatically in a deep energy well, created by tuning an externally applied magnetic field. The simultaneous electrostatic confinement of electrons and magnetic confinement of ions avoids anomalous transport and facilitates classical containment of both electrons and ions. In this configuration, ions and electrons may have adequate density and temperature so that upon collisions they are fused together by nuclear force, thus releasing fusion energy. Moreover, the fusion fuel plasmas that can be used with the present confinement system and method are not limited to neutronic fuels only, but also advantageously include advanced fuels.
The pdf of the patent can be downloaded here
The google copy of the patent is complete.
The patent is interesting reading to get insight into what Tri-alpha Energy is trying to achieve and how what they are doing compares to some other nuclear fusion approaches. Tri-alpha Energy has been very secretive about their work, but they have received about $50 million in funding. Tri-Alpha Energy had previously indicating that they believed that they could achieve the prototype for commercial nuclear fusion (net positive energy at the scale of a commercial plant) at about the 2015-2020 timeframe.
From the Patent
A major innovation of the present (FRC) invention over all previous work with FRCs is the simultaneous electrostatic confinement of electrons and magnetic confinement of ions, which tends to avoid anomalous transport andfacilitate classical containment of both electrons and ions. In this configuration, ions may have adequate density and temperature so that upon collisions they are fused together by the nuclear force, thus releasing fusion energy.
In a preferred embodiment, a plasma confinement system comprises a chamber, a magnetic field generator for applying a magnetic field in a direction substantially along a principle axis, and an annular plasma layer that comprises a circulatingbeam of ions. Ions of the annular plasma beam layer are substantially contained within the chamber magnetically in orbits and the electrons are substantially contained in an electrostatic energy well. In one aspect of one preferred embodiment amagnetic field generator comprises a current coil. Preferably, the system further comprises mirror coils near the ends of the chamber that increase the magnitude of the applied magnetic field at the ends of the chamber. The system may also comprise abeam injector for injecting a neutralized ion beam into the applied magnetic field, wherein the beam enters an orbit due to the force caused by the applied magnetic field. In another aspect of the preferred embodiments, the system forms a magnetic fieldhaving a topology of a field reversed configuration.
In another aspect of the preferred embodiments, an annular plasma layer is contained within a field reversed configuration magnetic field. The plasma layer comprises positively charged ions, wherein substantially all of the ions arenon-adiabatic, and electrons contained within an electrostatic energy well. The plasma layer is caused to rotate and form a magnetic self-field of sufficient magnitude to cause field reversal.
In other aspects of the preferred embodiments, the plasma may comprise at least two different ion species, one or both of which may comprise advanced fuels.
Having a non-adiabatic plasma of energetic, large-orbit ions tends to prevent the anomalous transport of ions. This can be done in a FRC, because the magnetic field vanishes (i.e., is zero) over a surface within the plasma. Ions having a largeorbit tend to be insensitive to short-wavelength fluctuations that cause anomalous transport.
Magnetic confinement is ineffective for electrons because they have a small gyroradius--due to their small mass--and are therefore sensitive to short-wavelength fluctuations that cause anomalous transport. Therefore, the electrons areeffectively confined in a deep potential well by an electrostatic field, which tends to prevent the anomalous transport of energy by electrons. The electrons that escape confinement must travel from the high density region near the null surface to thesurface of the plasma. In so doing, most of their energy is spent in ascending the energy well. When electrons reach the plasma surface and leave with fusion product ions, they have little energy left to transport. The strong electrostatic field alsotends to make all the ion drift orbits rotate in the diamagnetic direction, so that they are contained. The electrostatic field further provides a cooling mechanism for electrons, which reduces their radiation losses.
The increased containment ability allows for the use of advanced fuels such as D-He.sup.3 and p-B.sup.11, as well as neutronic reactants such as D-D and D-T. In the D-He.sup.3 reaction, fast neutrons are produced by secondary reactions, but arean improvement over the D-T reaction. The p-B.sup.11 reaction, and the like, is preferable because it avoids the problems of fast neutrons completely.
Another advantage of the advanced fuels is the direct energy conversion of energy from the fusion reaction because the fusion products are moving charged particles, which create an electrical current. This is a significant improvement overTokamaks, for example, where a thermal conversion process is used to convert the kinetic energy of fast neutrons into electricity. The efficiency of a thermal conversion process is lower than 30%, whereas the efficiency of direct energy conversion canbe as high as 90%.
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