| ...Fusion Reactions In Atomic Scale Accelerators |
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A sub-nuclear resolution microscopic accelerator just a few centimeters long and only a few nano-meter wide will initiate individually controlled fusion reactions without requiring thermonuclear temperatures or expensive magnetic confinement. For years, researchers have created precise atomic structures using precise matter beam positioning and\or replication. Recently researchers have created an atomically perfect ring of copper atoms to create an electron standing wave pattern. Other researchers have created various other atomic scale structures such as nanometer-sized tubes and Buckminster Fullerenes for years. Variations of these structures can be assembled to create an atomic scale particle accelerator capable of accelerating a tritium nucleus and a deuterium nucleus and accomplishing their collision with sub atomic, sub-nuclear, or even sub-proton, accuracy. Conventional fusion reactors are all based on confining the reaction products at a high enough temperature and pressure to achieve a statistical probability of enough high energy random collisions to induce a sustainable fusion reaction. In contrast, individual atoms collided with sub nuclear accuracy can be induced to fuse with only 51 KeV of energy. I understand that this is a highly speculative idea. Nonetheless, the great potential for microscopic fusion reactors deserves attention. Nuclear fusion with nuclear accuracy atomic scale accelerators does not require extremely high temperatures and confinement required by thermonuclear reactions: Thermonuclear reactions take advantage of E= 3/2kT. Thus, using a standard formula for deriving temperature from average molecular collision energy, assuming 10 KeV collisions taking place in a 10^15 density plasma the temperature must be: T=2/3(Joules)/1.38*10-23J/K T=2/3(104 eV)(1.6*10-19 J/eV)/1.38*10-23J/K T=77M degrees K In practice, an ignition temperature of 400M K is needed to compensate for lost energy. For plasmas of low density, this incredibly high temperature equates to particle collisions of a relatively modest 51 KeV. This energy can be imparted using standard electrostatic acceleration or one can add laser or microwave assisted acceleration. Existing 51 KeV accelerators can impart this much energy to colliding ions, but cannot guarantee that many of the ions will actually collide because the beam is wide and atoms are small. If the atoms can individually be accelerated and aimed with sub-nuclear precision, then a high percentage of the ions can collide and fuse. If even only 10% of the ions accelerated actually collided and fused a large net energy gain would be realized. The potential electrostatic repulsive energy of deuteron centers 3 nuclear radii from each other is 2.72*105 eV from a standard handbook. Thus 51 KeV will force deuteron nuclei to overlap closely enough to fuse. Practical considerations Vacuum Breakdown voltage is 1.25MV/cm in vacuum or 125 KV/mm. Thus a 50 KeV accelerator might be as small as 406 micrometers long. At these small sizes, other factors may strongly influence the practical length required. Glass, for instance can only support 35 KV/cm. Some of the best insulators can withstand 200 KV/cm. Various recent technological achievements indicate that the accuracy for constructing and aligning the accelerator can be high enough. As mentioned earlier, various atomic structures have been constructed in the laboratory. Several sensing methods are also have resolution in the nuclear range, that might facilitate their use for alignment. Capacitance micrometry, for instance, is a very sensitive method for detecting small displacements. This method works by measuring the change in the impedance of a parallel plate capacitor as the spacing or area of the parallel plates changes. Displacements as small as 10 femto-meters (10e-14m) about the diameter of an electron or 10,000 times smaller than an atom can be measured using this technique. The Deuteron ion trajectory can be electrostatically deflected. The atoms in the accelerator can be accurately placed on the substrate crystal lattice. The thermally induced vibrations of the accelerator atoms will average out over some 109 atoms. The electrostatic potential on the deflection plates can be adjusted with very high precision including down to the adding and subtracting of individual electrons. The actual frequency of occurrence of fusion events can be used as feedback for the accurate deflection of the accelerated particles. Production methods: We can start by looking into direct assembly using piezo or magnostrictive elements and structures similar to those used in Scanning tunneling microscopes and used by other researchers to assemble nano structures. Most mass production will probably take place with nanoassemblers and superfocus replicators. Choice of atomic reaction: Compared to Deuterium-Deuterium the Deuterium-Tritium reaction ignition temperature is only 4.4 KeV for a reaction energy of 14 MeV vs. an ignition temperature of 48 KeV For reaction energy around 3.7 MeV. However the Deuterium-Tritium reaction puts out high energy neutrons that destroy the reactor chamber and make it radioactive. The possibility of accelerator based reactions reliably achieving high energy nuclear reactions suggest the possibility of looking at other nuclear reactions that are less radioactive then the deuterium-tritium reaction. The Deuterium-Deuterium reaction is a good reaction to start with since it is well understood and creates less radioactivity then tritium deuterium reactions, and most ships carry dueterium fuel around anyway. Another disadvantage of tritium is that it must be made in a reactor using lithium and thus is not as common as deuterium. It would be, of course, be good to eliminate any radioactivity. The following reactions are reported to be completely Non-radioactive: 1/1H + 11/5B => 4/2 He + 8.68 MeV. b Boron 11 and Plain Hydrogen are the dominant isotopes and both are common. Another possible radiation free reaction is: Deuterium + He3 => 4/2He (3.6 MeV) + 1/1H (14.7 MeV) Both reaction products are charged so that direct electrical energy recovery is possible. He3 is rare on Earth: 1.4 Atoms per M atoms air. Moon rocks and Jupiter and Saturn have more of it. Ships that have more advanced impulse engines, such as the Excal and some upgraded Prometheus class ships, can use this first shot. Generating useful amounts of power: The energy from each reaction for the Deuterium-Deuterium reaction products is 4 and 3.3 MeV. Taking 3.7 MeV as the energy: 3.7 MeV =2.884*10-18Joules. Thus 3.468 *1017 reactions per second must take place to generate 1 W of energy. Given the speed of the particle particles = [(2*Volts*1.6*10-19)/mass].5, 1 , generating 1 watt with a single accelerator requires a line of 10 meters of hydrogen ions packed 2 radii apart per second. 1 W is also an extremely large amount of energy to dissipate for one nano-meter sized reaction chamber. Thus multi-watt devices will require many multiple accelerators running in parallel, perhaps using 50 nm glass tubes doped to be slightly conductive. The energy theoretically available from fusion is of course vast. A 3 GW fusion plant would require .455 grams/day of deuterium, from 13 k Kg/day of sea water. This plant would be half the size of conventional reactors; unfortunately, at this time it is impossible to use muon-proton bonding to increase the fusion rate. |
