The principle of the S.T.A.R. fusion reactor is quite unlike any other IEC reactors, such as the Farnsworth reactor. At first glance it might look similar, because it is an IEC reactor, but unlike virtually all other IEC reactors, the S.T.A.R. reactor does not have a wire grid cathode, which since the 1950's has been the achilles heel of the IEC fusion reactors.
Traditional fusors, such as the Farnsworth design, suffer from large current losses due to ion collisions with the grid, initially each collision causes a number of electrons to be knocked out of the grid surface and second it causes heating of the grid, making the grid an effective cathode ray emitter at the expence of power consumption.
Unlike traditional fusors, the S.T.A.R. reactor can create an incredibly deep negative potential energy well, with virtually zero electron losses from the cathode. It achieves this by surrounding 95% of the cathode with a strong dielectric material effectively insulating it from the anode, leaving only a small apperture through which accelerated ions of reactive gases can be injected into the cathode.
The dielectric of choice for a heat producing reactor, is transformer oil, which also happens to be a superb neutron moderator. So as one can see from the animation above, the S.T.A.R. reactor has solved the problem of electron losses and at the same time built in a way to convert the kinetic energy of the fusion products and the neutrons into heat. As the neutrons traverse the transformer oil, they collide with atoms in the hydrocarbon based transformer oil, and deposit their kinetic energy into the fluid.
The S.T.A.R. reactor becomes more efficient when it is scaled up in size,becase higher voltages can then be applied, thereby increasing the depth of the potential energy well and consequently increasing the fusion reaction rates.
In applications where fast neutrons are required, the transformer oil can be replaced with an alternative dielectric, such as ceramic. The fast neutrons will travel through the ceramic with less interaction and therefore emerge from the reactor at higher energies.As with all fusion reactors, the choice of fuel is critical to the ultimate performance. It has been predicted that the S.T.A.R. fusion reactor will work more efficiently with fusion fuels that have a large portion of charged fusion products, because the kinetic energy from those kind of reactions will be retained in the cathode. Fusion fuels that emit a large portion of their energy as fast neutrons are less desirable.