Saturday, January 02, 2016
Based on a technological concept originating in 1964, LPP Fusion is developing a dense plasma focus (DPF) device. No external magnetic field is required, since the method generates its own magnetic field --- making it potentially much more compact than mainstream fusion technologies.
For a few millionths of a second, an intense current flows from an outer to an inner electrode through a low pressure gas. This current starts to heat the gas, creating an intense magnetic field. This in turn generates a super-dense plasma, condensed into a tiny ball only a few thousandths of an inch across called a plasmoid. Again, all of this happens without being guided by external magnets.
The magnetic fields very quickly collapse, and these changing magnetic fields induce an electric field which causes a beam of electrons to flow in one direction and a beam of ions – atoms that have lost electrons – in the other. The electron beam heats the plasmoid to extremely high temperatures, the equivalent of billions of degrees C (particles energies of 100 keV or more). (This temperature level is orders of magnitude hotter than the core of the sun, and many times hotter than alternative fusion power technologies.)
This technology can in principle be used to produce X-rays or to generate fusion power.
To create fusion power, energy can be transferred from the electrons to the ions using the magnetic field effect. Collisions of the ions with each other cause fusion reactions, which add more energy to the plasmoid. Thus, in the end, the ion beam contains more energy than was input by the original electric current. (The energy of the electron beam is dissipated inside the plasmoid to heat it.) This happens even though the plasmoid only lasts 10 ns (billionths of a second) or so, because of the very high density in the plasmoid, which is close to solid density. This level of density makes nuclear collisions (and thus fusion reactions) very likely, and they occur extremely rapidly.
The ion beam of charged particles is then directed into a decelerator which acts like a particle accelerator in reverse. Instead of using electricity to accelerate charged particles, they decelerate charged particles and generate electricity. Some of this electricity is recycled to power the next fusion pulse while the excess (net) energy is the electricity produced by the fusion power plant. Some of the X-ray energy produced by the plasmoid can also be directly converted to electricity through the photoelectric effect (as occurs in solar panels).
An interesting aspect of the DPF design is that it generates sufficient temperature levels to power fusion reactions in elements with higher molecular weights, which in turn holds out the promise of a shortcut to boronic fusion, the "holy grail" of fusion power research, as this particular fusion reaction generates electricity rather than neutron radiation... and electricity is what we actually want!
Another interesting feature here is that LPP Fusion is an incorporated company (in this sense, similar to General Fusion), and thus they accept investments from private contributors. Again, this is all "micro" scale when compared, say, to Exxon Mobil or Conoco Phillips, but at least a base has been established to which further investments can be added.....