Patent Application
20200231309
The present invention relates to air or space craft for delivery of personnel and supplies from one location to another, and especially to such craft for use over the surfaces of the Moon, Mars, other planets or moons, as well as asteroids and similar space bodies. The invention also relates to inducement or production of controlled nuclear fusion by particle-target and muon-catalyzed micro-fusion for thrust in the presence of ambient cosmic rays and muons.
For future creation of bases on the Moon and eventually on Mars, there will be a need to efficiently move personnel and supplies from place to place. Surface transport may sometimes be difficult because of terrain. However, there is no atmosphere on the Moon to support aerial flight, so another means of providing thrust and lift must be used. Although Mars does have an atmosphere, it is extremely thin (an average of 600 Pascals or only 0.6% of Earth's atmospheric pressure), and while gravity is only about 38% of that on Earth, aerial-style flight will be extremely difficult (e.g. number and length of rotor blades and their speeds would collectively need to increase about 60-fold for comparable lift).
At some high-altitude locations on Earth, aerial movement of personnel and supplies is difficult because it requires supporting infrastructure for landing of planes (airport runways, etc.) and exceeds maximum altitudes for safe operation of helicopters (which have a small landing footprint and don't need an airport).
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 (about 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 break-even potential.
Another controlled fusion technique is particle-target fusion which comes from accelerating a particle to sufficient energy 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 cosmic rays are abundant in interplanetary space. Cosmic rays are mainly high-energy protons (with some high-energy helium nuclei as well) with kinetic energies in excess of 300 MeV. Most cosmic rays have GeV energy levels, although some extremely energetic ones can exceed 1018 eV.
Cosmic rays are known to generate abundant muons from the decay of cosmic rays passing through Earth's atmosphere. Cosmic rays lose energy upon collisions with atmospheric dust, and to a lesser extent atoms or molecules, generating 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. Near sea level on Earth, the flux of muons generated by the cosmic rays' interaction by the atmosphere averages about 70 m−2s−1sr−1. The muon flux is even higher in the upper atmosphere. These relatively low muon flux levels on Earth reflect the fact that both Earth's atmosphere and geomagnetic field substantially shield our planet from cosmic ray radiation, although the amount of shielding is somewhat lower and thus the cosmic ray flux and muon generation are greater at higher elevations and altitudes. Mars is a different story, having very little atmosphere (only 0.6% of Earth's pressure) and no magnetic field, so that muon generation at Mars' surface is expected to be very much higher than on Earth's surface.
The present invention provides micro-fusion powered craft for use above the lunar and Martian surfaces, where the micro-fusion provides thrust for generating lift and propulsion. The propulsion technology takes advantage of the abundance of cosmic rays in space to catalyze fusion events in enough amounts to produce useable thrust. The cosmic rays together with muons generated from such cosmic rays are available here for free and do not need to be generated artificially in an accelerator. The thrust enables flight above the lunar or planetary surface, including an ability to haul cargo and personnel up to some maximum weight that is dependent upon the amount of lift and propulsion provided by the micro-fusion.
A craft is provided with a centrally located internal chamber with a dome on top and opening at the bottom. A small amount of deuterium-containing micro-fusion fuel material is inwardly injected into this chamber. Ambient cosmic rays and/or muons penetrate the dome from above and interact with the fuel material to generate energetic alpha particles and/or other reaction products that provide lifting thrust to the craft. In particular, downwardly-directed alpha particles escape through the opening to produce an upward reaction thrust, while upwardly-directed alpha particles are stopped by the dome and produce upward applied forces against the craft. Further, any fuel escaping through the bottom opening will also react externally with ambient cosmic rays and muons and resulting reaction products will apply upward forces upon the underside of the craft.
For lateral motion, the attitude of the craft may be tilted (e.g. by shifting center of mass) so that the thrust will have a lateral as well as vertical component. Alternatively, the location of the opening at the bottom of the chamber might be moveable so that the selection of which generally downward-directed alpha particles escape and produce reaction thrust can vary. Still further, the bottom opening may have a deflection mechanism (e.g. based on electrostatic fields) that redirects or steers some or all the escaping alpha particles in a more lateral direction.
The craft might also be provided with a set of external side ports for lateral motion. Deuterium-containing micro-fusion fuel material is ejected from one or more selected ports to form a cloud of material that interacts with the ambient cosmic rays and/or muons. Energetic micro-fusion reaction products interact with the side of the craft to provide lateral thrust moving the craft in a desired direction.
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The dome 15 is effectively transparent to cosmic rays, with their extremely high energies (>100 Mev) and penetrating power, but essentially opaque to the substantially lower energy (˜10 MeV) alpha particle reaction products that will thus be stopped by the dome. It is expected that the dome material can be the same as the external skin 12 of the craft 11, but thinner. However, research and development efforts may optimize the choice of dome material and its thickness to achieve maximum cosmic ray penetration into the chamber 13, as well as to facilitate production of muons through interactions of those cosmic rays with the dome material. The dome 15 might even be double-paned structure with wire mesh, fibers and or even fine particulates to enhance muon creation. (Such a double-paned structure may also facilitate the provision of a cooling water or gas flow between the panes.) Such the presence of muon generators as a permanent structure of the dome 15 will lessen or even eliminate the need for having muon-generating particulate material with the fuel, thereby saving valuable fuel weight.
Additionally, the amount of curvature of the dome may be important to maximizing input of cosmic rays and muons into the chamber 13. The curvature of the “dome” may range from being completely flat to extending considerably upward above the top of the remainder of the craft 11, perhaps as much as twice as high as its radius. The much larger surface area of a large curvature dome 15 would facilitate cooling of the cover as it bombarded with ambient cosmic rays penetrating from outside and with micro-fusion reaction products (energetic alpha particles a) from within. A larger curvature might also allow relief of mechanical stresses from any heating that does result.
Except for fuel injection ports 19 leading into the chamber 13, the internal chamber is otherwise isolated from the rest of the craft 11 that radially surrounds it. Specifically, the sides 14 of the chamber 13, seen in
One or more fuel injection ports 19 are positioned in the sides 14 of the chamber 13 for ejecting micro-fusion fuel particles 25 from a stored supply 21 to create a cloud 27 of such material within the chamber 13. Ambient cosmic rays 29 and muons p generated from those cosmic rays penetrate the dome 15 and react with the cloud 27 of micro-fusion material to generate energetic fusion products, such as alpha particles a. At least some of these energetic fusion products are received by the craft 11 to provide upward thrust or lift. Specifically, some of the alpha particles a will be directed downward and escape through the opening 17 at the bottom of the chamber. These will provide an upward reaction thrust. Other alpha particles a will be directed upward and be stopped by the dome 15. These will produce an upward applied force against the craft 11. Alpha particles a directed laterally in all directions will provide counteracting effects and negligible thrust contributions. Some of the deuterium-containing micro-fusion fuel material will also escape through the opening 17 in the bottom of the chamber 13. However, immediately outside the craft 11, such fuel will also interact with ambient cosmic rays and muons to generate micro-fusion reaction products (alpha particles a) at least some of which will be directed upward onto the underside of the craft 11. These will likewise apply an upward force upon the craft 11. The combination of contributing upward forces will produce lift.
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Using any of these methods a pilot can vary the speed and direction of the craft 11 by varying the amount and direction of lateral thrust provided by the alpha particles.
The fuel can be solid Li6D in powder form, D-D or D-T inertial-confinement-fusion-type pellets, or D2O ice crystals, or even droplets of (initially liquid) D2. Various types of micro-fusion reactions may also occur, such as Li6-D reactions, generally from direct cosmic ray collisions, as well as D-T, using tritium generated by cosmic rays impacting the lithium-6. D-T reactions especially may be assisted by muon-catalyzed fusion.
The dispersed cloud of micro-fusion target material will be exposed to ambient cosmic rays and muons. To assist muon formation, the micro-fusion fuel material may contain up to 20% by weight of added particles of fine sand or dust. As cosmic rays collide with the micro-fusion material and dust, they form muons p that are captured by the deuterium and that catalyze fusion. Muon formation may also be facilitated by reaction of cosmic rays with the dome material. Likewise, the cosmic ray collisions themselves can directly trigger particle-target micro-fusion.
The amount of energy generated by the micro-fusion reactions, and the thrust the micro-fusion products produce, depends upon the quantity of fuel injected into the chamber 13 and the quantity of available cosmic rays and muons in the ambient environment that can enter the craft through the dome 15. Assuming much of the energy can be captured and made available for thrust, an estimated 1015 individual micro-fusion reactions (less than lpg of fuel consumed) per second would be required for 1 kW output. But as each cosmic ray can create hundreds of muons and each muon can catalyze about 100 reactions, the available cosmic ray flux in interplanetary space (believed to be several orders of magnitude greater than on Earth) is believed to be sufficient for this thrust purpose following research, development, and engineering efforts.
The micro-fusion fuel material may be sprayed continuously as needed to sustain the clouds both within the chamber 13 and externally adjacent to the craft 11. For the external side ports 33, the fuel can be ejected in the form of projectiles. The projectiles would then chemically explode when it reaches a desired distance from the craft 11 to disperse its micro-fusion particle fuel load and create the external cloud. The amount of micro-fusion target material expended is quite small, since less than 1 μg of fuel material reacted per second would be required for 1 kW output. Exact amount of fuel needed will depend upon the ambient cosmic ray and muon flux and the reaction cross-sections for achieving the desired number (e.g. 1015) of reactions per second.
The volume of the continuous slow fusion creates high velocity fusion products (fast alpha particles or helium “wind”, etc.) that bombard the exterior of the craft. The energetic alpha particle micro-fusion products (a) provide thrust against the craft.
Stored fuel 21 will be shielded within the craft 11 to reduce or eliminate premature micro-fusion events until delivered and dispersed as a cloud in the interior chamber or outside the craft for thrusting. However, one need not completely eliminate cosmic rays or their secondary particles (pions, muons, etc.) to zero, but merely reduce their numbers and energies sufficiently to keep them from catalyzing large numbers of micro-fusion events in the stored target particle material.
The muon-catalyzed and direct particle-target micro-fusion for providing the thrust may be used on the Moon, Mars, Martian moons, asteroid or possibly even Earth for lightweight craft at higher elevations and altitudes. Simple, inexpensive observation drones can be operated at a variety of altitudes and speeds. The design can be optimized for a particular space body. Specifically, as in
Because the technology is still early in a developmental phase, testing of its concepts might be perfected at some locations on Earth before its deployment in outer space, even though the ambient flux of cosmic rays and muons is expected to be orders of magnitude lower due to Earth's geomagnetic field and thick atmosphere. For testing purposes, ultra-lightweight drone craft under 5 kg may be used, especially at higher altitudes. (Both cosmic ray flux and muon generation are known to substantially increase with altitude.) Testing with ultra-lightweight craft at convenient higher altitude Earth locations would allow designers to improve the proposed micro-fusion engines before their use on the Moon and then on Mars. Additionally, such craft might serve to deliver supplies on Earth at higher elevations and altitudes, especially wherever a small landing footprint is needed but elevations are too high for helicopters to reach.
When used on Earth, some care will be needed when using some micro-fusion fuels. For example, lithium hydride (including Li6D) is known to be violently chemically reactive in the presence of water. While reactions with water are not a problem on the Moon or Mars, with any Earth applications the fuel material will need to be encapsulated to isolate it from water sources, including atmospheric vapor. A desiccant can also be used when storing the fuel material.
