The present invention relates to inducement or production of controlled nuclear micro-fusion using fuels in solid pellet, chip, capsule or other condensed-matter forms, for use on surfaces of the Moon, Mars, on other planets or moons having little or no magnetic field and/or atmosphere, and at very-high Earth altitudes, and relates in particular to muon-catalyzed micro-fusion as well as particle-target micro-fusion from ambient irradiation and bombardment with high-energy cosmic rays and their muon decay products.
Muon-catalyzed fusion was observed by chance in late 1956 by Luis Alvarez and colleagues during evaluation of liquid-hydrogen bubble chamber images as part of accelerator-based particle decay studies. These were rare proton-deuteron fusion events that only occurred because of the natural presence of a tiny amount of deuterium (one part per 6400) in the liquid hydrogen. It was quickly recognized that fusion many orders of magnitude larger would occur with either pure deuterium or a deuterium-tritium mixture. However, John D. Jackson (Lawrence Berkeley Laboratory and Prof. Emeritus of Physics, Univ. of California, Berkeley) correctly noted that for useful power production there would need to be an energetically cheap way of producing muons. The energy expense of generating muons artificially in particle accelerators combined with their short lifetimes has limited its viability as an earth-based fusion source, since it falls short of breakeven potential.
Another controlled fusion technique is particle-target fusion which comes from accelerating a particle to sufficient energy so as to overcome the Coulomb barrier and interact with target nuclei. To date, proposals in this area depend upon using some kind of particle accelerator. Although some fusion events can be observed with as little as 10 KeV acceleration, fusion cross-sections are sufficiently low that accelerator-based particle-target fusion are inefficient and fall short of break-even potential.
It is known that abundant muons can be derived from the decay of cosmic rays passing through a planet's atmosphere. Cosmic rays are mainly high-energy protons (with some high-energy helium nuclei as well) having kinetic energies in excess of 300 MeV. Most cosmic rays have GeV energy levels, although some extremely energetic ones can exceed 1018 eV.
In regions that are outside of Earth's protective magnetic field (e.g. in interplanetary space, or on planets or moons lacking a strong magnetic field), the cosmic ray flux is expected to be several orders of magnitude greater. As measured by the Martian Radiation Experiment (MARIE) aboard the Mars Odyssey spacecraft, average in-orbit cosmic ray doses were about 400-500 mSv per year, which is at least an order of magnitude higher than on Earth.
It is known that as cosmic rays lose energy upon collisions with atmospheric dust, and to a lesser extent atoms or molecules, they generate elementary particles, including pions and then muons, usually within a penetration distance of a few cm. Typically, hundreds of muons are generated per cosmic ray particle from successive collisions. For example, near sea level on Earth, the flux of muons generated by the cosmic rays' interaction by the atmosphere averages about 70 m−2 s−1 sr−1. The muon flux is even higher in the upper atmosphere. These relatively low flux levels on Earth reflect the fact that both Earth's atmosphere and geomagnetic field substantially shields our planet from cosmic ray radiation. Mars is a different story, having very little atmosphere (only 0.6% of Earth's pressure) and no magnetic field, so that cosmic ray flux and consequent muon generation at Mars' surface is expected to be very much higher than on Earth's surface.
In recent years, there have been proposals to send further spacecraft to Mars in 2018 and then manned space vehicles to Mars by 2025. One such development project is the Mars Colonial Transporter by the private U.S. company SpaceX with plans for a first launch in 2022 followed by flights with passengers in 2024. The United States has committed NASA to a long-term goal of human spaceflight and exploration beyond low-earth orbit, including crewed missions toward eventually achieving the extension of human presence throughout the solar system and potential human habitation on another celestial body (e.g., the Moon, Mars). As part of any manned exploration and human habitation of Mars, one or more forms of heating and lighting, and liquid water, will be needed for the habitats and life support.
Various units are described that use a coating of chips or pellets comprising a deuterium-containing micro-fusion fuel material to produce energetic reaction products and/or EM radiation in the presence of an ambient flux of cosmic rays and muons generated from the cosmic rays. The chips may contain solid Li6D or encapsulate liquid or frozen D2O. Micro-fusion reactions proceed via muon-catalyzed fusion, particle-target fusion, or both. These may produce usable heat for a space heater to heat surrounding spaces directly or communicate via circulating fluid with a heat exchanger located for more remote heating of spaces away from the generator. EM radiation (usually, but necessarily exclusively, in the form of x-rays or gamma-rays) can be converted to electricity, either directly or via heating of a circulating liquid and thermoelectric conversion. Mechanical work may also be performed by the energetic reaction products, wherein a coated panel mounted on a transport vehicle may serve as a propulsion unit, the energetic reaction products directly providing horizontal thrust or providing electricity via heating (as before) to drive the vehicle. Other mechanical devices include paddle wheels coated with the chips to generate rotary motion, and levers coated on one lever arm to produce at the other lever arm.
Mars, with an atmospheric pressure that is only 0.6% of Earth's pressure, allows a substantial flux of cosmic rays to reach the planetary or lunar surface and its high mountains. Therefore, locating a solid fusion pellet or chip target on the surface of Mars (or any other planet or moon with a thin atmosphere) can make use of the muon generation from such cosmic rays in order to catalyze fusion. A solid chip target (such as Li6D) is preferred, but a properly contained liquid target (e.g., a chip of encapsulated D2O) would also work in some less demanding applications since both cosmic rays and muons have sufficient energy to pass through a capsule's coating to interact with the liquid or frozen target material contained within the capsule.
The muons (and cosmic rays) are available here for free and do not need to be generated artificially in an accelerator. One cosmic ray particle can generate hundreds of muons, and each muon can typically catalyze about 100 fusion reactions before it decays (the exact number depending on the muon “sticking” cross-section to any helium fusion products). Additionally, any remaining cosmic rays can themselves directly stimulate a fusion event by particle-target fusion, wherein the high energy cosmic ray particles (mostly protons, but also helium nuclei) bombard relatively stationary target material.
Created by collisions of cosmic ray particles with atmospheric dust and molecules, muons are used in several ways in the present invention. The main reaction is in catalyzing fusion of two deuterium nuclei. The deuterium “fuel” may be supplied in the form of solid LiD chips, or even encapsulated heavy water (D2O) or liquid deuterium (D2). Other types of fusion reactions besides D-D are also possible depending upon the target material. For example, another LiD reaction is Li6+D→2He4+22.4 MeV, where much of the useful excess energy is carried as kinetic energy of the two helium nuclei (alpha particles). Additionally, when bombarded directly with cosmic rays, the lithium may be transmuted into tritium which could form the basis for some D-T fusion reactions.
Since the amount of generated energy is on the order of kilowatts, which is very much less than the fusion energy outputs or yields typical of atomic weapons, “micro-fusion” is the term used here to refer to fusion energy outputs of not more than 10 gigajoules per second (2.5 tons of TNT equivalent per second), to thereby exclude runaway macro-fusion-type explosions.
In the present invention, muons from cosmic ray decay replace electrons in deuterium, allowing for a reduced size molecule because, as realized by Charles Frank in 1927, being about 200 times more massive than electrons, muons orbit much nearer to the central nucleus than the electron replaced. Muonic deuterium can come much closer to the nucleus of a similar neighboring atom with a probability of fusing deuterium nuclei, releasing energy. Once a muonic molecule is formed, fusion proceeds extremely rapidly (on the order of 10−10 sec). The muon is usually released to catalyze about 100 other fusion reactions during its short life (2ρs at rest, but longer at relativistic speeds generated by cosmic rays). Although D-D fusion reactions occur at a rate only 1% of D-T fusion, and produce only 20% of the energy by comparison, the freely available flux of cosmic-ray-generated muons on planets (such as Mars), moons with thin atmospheres, on the highest mountains on Earth, or via satellites in orbit around Earth should be sufficient to yield sufficient energy output by muon-catalyzed fusion for practical use. Energetic protons, which make up about 90% of the cosmic rays, must have a collision energy loss of at least 300 MeV for a muon to be created. Most cosmic rays are energetic enough to create multiple muons (often several hundred) by successive collisions with atmospheric dust or with the atoms in a fusion chip target. Any cosmic rays that reach a fusion chip target at the Martian surface with sufficient residual energy can also directly induce some nuclear fusion events by particle-target type fusion, supplementing those obtained from the muons.
The present invention achieves muon-catalyzed nuclear fusion using deuterium-containing target material, and muons that are naturally created from ambient cosmic rays. Most cosmic rays are energetic enough to create multiple muons (often several hundred) by successive collisions with atmospheric dust or with the atoms in a target. In fact, most cosmic rays have GeV energies, although some extremely energetic ones can exceed 1018 eV and therefore potentially generate millions of muons. The optimum concentration of the fusion chip target material for the muon-catalyzed fusion may be determined experimentally based on the particular abundance of cosmic rays with a view to maintaining a chain reaction of fusion events for producing adequate heat, useful work or illumination photons for the specified application while avoiding any possibility of runaway fusion in the muon rich environment (each muon can catalyze multiple fusion events, as many as 100, before it eventually decays).
At a minimum, since muon-catalyzed fusion, while recognized, is still an experimentally immature technology (since measurements have only been conducted to date on Earth using artificially generated muons from particle accelerators), various embodiments of the present invention can have research utility to demonstrate feasibility in environments beyond Earth's protective atmosphere and/or geomagnetic field, initially above Earth's atmosphere (e.g. on satellite platforms or Earth's highest mountain tops) for trial purposes, and then on the Moon or the surface of Mars, in order to determine optimum parameters of the fusion chip arrays for various utilities in those environments. For example, the actual number of muon catalyzed fusion reactions for various types of fusion chip target configurations and fusion fuel sources, and the amount of heat, illumination, or useful work that can be derived from such reactions, are still unknown and need to be fully quantified in order to improve the technology.
With reference to
In either case, the chips may contain solid Li6D or may encapsulate liquid or frozen D2O. However, even a Li6D chip material should be coated with an inert material to protect it against adverse chemical reaction during manufacture, transport and in the launch vehicle. The plates containing the fusion chip material should also be shielded against premature interactions with cosmic rays during its long travel to its destination. When subject to cosmic ray collisions, the disks become hot from the resulting fusion reactions. The optimum size of the tiny chips and the spacing between them can be determined with routine experimentation to ensure an adequate chain of fusion events that generate useful heat without runaway fusion.
As seen in
Alternatively, as seen in
Alternatively, as seen in
Thus, a fusion chip space heater can be created and seated on the Martian surface, where the fusion source material itself could be a cosmic ray target for the creation of muons, or where a separate cosmic ray target may be provided immediately adjacent to the fusion chip source material. Additionally, many muons naturally generated in the Martian atmosphere will arrive at the surface before decaying so as to be available to interact with the fusion source material. The kinetic energy of the fusion products can be transferred as heat to a metal lining, or tubes of water coupled to a heat exchanger. The kinetic energy could also be directly converted into electricity by any of a number of techniques including electrostatic collection. Photoelectric conversion of electromagnetic radiation may be possible using concentrically nested X-ray absorber and electron collector sheets (cf. U.S. Pat. No. 7,482,607 and U.S. Patent Application Publication 2013/0125963).
The space heater would be useful for providing warmth to designated spaces, such as mountain tops and underground dwellings 60 of a Mars colony. As seen in
In yet another possible construction, shown in
In yet another possible application, if the reaction rate can be optimized, the series of controlled fusion micro-explosions could be used to propel wheels or pistons to achieve physical motion (similar to driving the paddles of a water wheel or pistons of a combustion engine), where a surface to be propelled by the micro-explosions is coated with the fusion fuel material and exposed to cosmic rays and the cosmic-ray-generated muons. For example, as seen in
This application claims priority under 35 U.S.C. 119(e) from prior U.S. provisional application 62/372,618, filed Aug. 9, 2016.
Number | Date | Country | |
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62372618 | Aug 2016 | US |