|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
This table presents several nuclear fusion reactions of interest. The first symbol in the equation represents the target nucleus. Next is the bombarding particle, followed by the product particle. The last symbol designates the product nucleus. So the first equation reads: a hydrogen nucleus with a mass of two (one proton and one neutron, a.k.a. deuterium) is smacked with a deuteron (the same thing) and produces a neutron and a helium nucleus with a mass of three (two protons and one neutron) along with an amazing amount of energy. This same reaction can produce a second set of products (and about half the time it does) which are shown in the second equation. In this case the products are a proton (a hydrogen nucleus with a mass of one) and a hydrogen nucleus with a mass of three (a.k.a. tritium). Interestingly, both tritium and helium-3 will fuse with deuterium to produce even larger amounts of energy and helium-4. If we had a reactor capable of fusing deuterium, it would breed and burn even more potent fusion fuel and produce only stable helium-4. Deuterium is a naturally occurring isotope of hydrogen, the oceans contain megatons of it in "heavy water", which is easily separated.
So what does nuclear fusion have to do with high voltage? To answer that, let us turn back the clock to the late 1930's and the activities of one Philo T. Farnsworth. Philo was single handedly inventing broadcast television and designing all of the electron tubes (transistors are still two decades in the future) necessary to make it work. Sadly, shortly after his first public demonstration, the Japanese sucked us into World War Two. The government drafted Philo and put him to work at MIT's Radiation Laboratory where he developed a new toy, dubbed RAdio Detection And Ranging. As you may know, many people believe that radar won WWII (whereas the nuclear bomb only ended it). Clearly, Philo was a fairly bright individual.
Now, let's fast forward to the 60's. The cold war is in full swing. Television has become the Boob Tube. Philo is working as a wage slave at International Telephone and Telegraph. At this time ITT had an active nuclear physics program and the hot topic was controlled fusion. I don't know the circumstances, but apparently Philo learned about the fusion problem and realized that he already knew how to solve it. In his earlier work with electron tubes he had developed a diode tube to handle enormous currents using what he termed virtual electrodes (actually, inertially confined plasma). The device consists simply of a spherical wire grid inside of an evacuated spherical conductive shell. Placing a high negative potential on the inner grid causes ionization of the residual gas and acceleration of the cations towards the center of the device where a high density plasma is formed. This plasma is then continuously bombarded with high energy cations. Philo figured that if the tube was filled with a mixture of deuterium and tritium (two heavy isotopes of hydrogen that undergo fusion at relatively low energy) the plasma density and bombardment energy of his virtual electrode diode should be sufficient to initiate stable fusion. It worked great, generating lots of fast neutrons, helium and energy and Philo filed several patents (all assigned to ITT). About the same time that Philo was having success with his fusion reactor, ITT decided to ax its nuclear division. Philo was forced into retirement and died shortly thereafter. One of his collaborators from ITT got a look at what the Russians were doing with magnetically confined plasmas and loudly announced to the physics community that Tokamaks were the wave of the future for fusion research (this may have been due in part to disillusionment with all things ITT and the realization that ITT still held the patents on IEC fusion, essentially placing this area of research off limits to him) and IEC fusion was forgotten.
