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<\/figure>\n\n\n\nIntrinsically, particles and antiparticles are the same. Antiparticles follow the same particletheories and almost all laws of physics that particles adhere to, except to tiny differences that are negligible [13]. However, there is a significant difference in the abundance of these two materials in the world; the world around us is constituted entirely of matter [13]. A distinguished property of antimatter is the explosive annihilation it causes when mixed with matter. When matter-antimatter annihilation occurs, they both disappear, leaving their energy transformed into some other form [3]. It can take the form of energetic gamma rays immediately or can be in the form of intermediate particles that decay or undergo further annihilation [14]. Moreover, the energy released has an astronomical amount of double the rest mass of either particle, following Einstein\u2019s mass \u2013 energy equivalence [5]. That\u2019s why the annihilation reaction has an enormous energy density potential of around 90 billion MJ\/kg or 9 \u00d7 1016 J\/kg, which is higher than any other reaction known [15]. To depict this magnitude, this energy, kilogram for kilogram, is about ten billion times more than the hydrogen-oxygen combustion that powers space shuttles\u2019 main engines and 300 times more than the fusion reactions at the Sun\u2019s core [14]. If it was utilized as an energy source, the applications of antimatter would be infinite. Table 1 below compares the energy density of the most powerful propulsion sources and comments on their capabilities when used for spacecrafts for deep space missions. It is worth noting that the ambient field surrounding an antiparticle has a significant impact on its initial states, meaning that the annihilation reaction it undergoes is an environment-dependent reaction [16]. In the context of an antimatter engine concept, this fact is particularly significant as it allows a diverse range of performance parameters for the same system and reactions just by altering the initial conditions of the annihilation. In order to create an annihilation reaction, a collision between particles and antiparticles needs to be induced. These collisions could occur on a large scale, such as at high-energy cosmological events, or at an atomic scale [17]. Clearly, a large-scale collision is not possible to make by humans for the energy inputs and outputs it involves. So, this work will only consider atomic scale interaction mechanisms leading to annihilation. There are plenty of these mechanisms and they can be generally classified as follows [17]: <\/p>\n\n\n\n
- \n
- Direct annihilation without intervention. <\/strong><\/li>\n\n\n\n
- Radiative capture yielding a photon plus a positronium, a protonium, or a nucleonium in the case of electron\u2013positron interaction, antiproton\u2013proton interaction, or interaction with heavier particles, respectively. <\/strong><\/li>\n\n\n\n
- Rearrangement collisions where molecules, atoms, or ions form bound states prior to the actual annihilation. <\/strong><\/li>\n<\/ol>\n\n\n\n
Each mechanism requires different energy and particle conditions to contribute significantly to the annihilation reaction, thus demanding certain parameters regarding the system design and the electric and magnetic fields used. Therefore, each mechanism could be utilized for different mission purposes and system configurations. From the information displayed above, it is clear that antimatter holds a promising potential for the future. Due to that, the topic of antimatter has been gaining increasing interest and attention from many scientists. A nearly exponential growth trend can be seen in Fig. 3, which illustrates the research trend relevant to antimatter for the past 6 decades. The Scopus search revealed that publications on antimatter reached a total of 2790 from its beginning in 1958 until the year 2023. Before a basic understanding of the physics of antimatter in the period from 1958 to 1995, the number of publications on the topic was steady and very little, as the capabilities of antimatter annihilation has not been unveiled yet. However, a significant jump and a continual increase in the number of relevant research can be noticed after that period, with the maximum number of studies reaching 130 in 2015 and 2017. This was after the basic physical principles of antimatter were established, and a deeper understanding about antimatter annihilations, production, and control was being developed. Interestingly, the subject of antimatter has caught most of the attention for its space propulsion applications. As mentioned earlier, currently impossible missions, like interstellar ones, can only be achieved with such elite energy source. This has caught the attention of most antimatter researchers. Following Fig. 4, a word cloud of researched antimatter topics is presented, where a larger bubble corresponds to a larger number of studies conducted on that topic, and connections between bubbles indicate correlations between different research topics. The largest bubble is observed under space propulsion topics, followed by antimatter propulsion topics, illustrating that most antimatter research was done on its use as a potential fuel for propulsion. As a matter of fact, even the majority of the correlated topics branching out of propulsion bubbles focus on propulsion applications of antimatter. Hence why applications of antimatter on propulsion, mainly for space missions, are the prime focus of this article. Further, the implications of different aspects of antimatter, such as its production and control, are discussed relative to antimatter driven space vehicles in this article.\u00a0Annihilation types to consider Since there is an antiparticle for each particle, there are lots of combinations of annihilations to consider [18]. Despite that, only antiproton \u2013 nucleon (proton or neutron) and positron \u2013 electron annihilations are possible for space propulsion applications. This limitation is imposed by the necessity of storing the antimatter in a stable form for the long periods of time space missions last, and only antiprotons and positrons are stable enough [19]. Antineutrons are unstable and quickly decay into an antiproton, a positron, and an antineutrino. More critically, the only antimatter that can currently be produced is antihydrogen as will be discussed in the antimatter production section following [16,20]. 2.1. Electron \u2013 positron annihilation Electrons (e- ) have electron fields quantified by a positive value, and so positrons (antielectrons, symbol e+) have a negative electron field of an equal magnitude. When those two fields are added together, they naturally sum up to zero. When electron-positron annihilation occurs, the loss of their mass and fields excites the electromagnetic field and produces two gamma photons as shown in Fig. 5.\u00a0<\/p>\n\n\n\n
This process releases 1.02 MeV, which is much less than antiproton annihilations, but is still more than any reaction used for propulsion up till now. 2.2. Antiproton \u2013 nucleon annihilation In antiproton \u2013 nucleon (proton or neutron) annihilation, one third of the energy produced is converted into gamma rays, and the remaining two-thirds is released in the form of numerous particles [3]. The resulting particles are massive, charged, and short-lived [16]. Most importantly, they travel at relativistic speeds, thus having a great deal of kinetic energy that can be harnessed for thrust [3]. As for antiproton \u2013 proton (pp) annihilation, the reaction undergoes several stages occurring over a small period of time, as shown in Fig. 6. The initial antiproton \u2013 proton annihilation releases lots of particles: neutral, negative, and positive pions and kaons [3]. Pions make up around 99% of the particles released, leaving only 1% of kaons [16]. This small number of kaons also decay into pions. All pions then decay into neutrinos, gamma rays, and muons. Finally, muons decay into neutrinos and electrons or positrons. Keep in mind this is not a straightforward reaction as the number and energy of each of these particles immensely change throughout the process [16,21]. The energy released from this annihilation is about 1.8 \u00d7 1014 J per g of antiprotons [22]. This is 1010 times more than hydrogen-oxygen combustion and at least 100 times greater than that of fission or fusion reactions. To envisage this colossal number, one gram of antihydrogen reacted with a gram of hydrogen generates the same energy as 23 Shuttle External Tanks (ET).<\/p>\n\n\n\n
![\"\"](\"https:\/\/extractech.in\/wp-content\/uploads\/2025\/06\/image-1.png\")
<\/figure>\n\n\n\neaning that, one gram of antihydrogen could ideally power 23 space shuttles. It can be predicted in advance that antiproton-neutron (pn) annihilation would be different from the antiproton-proton (pp) one because of the difference in initial conditions. First, the net charge is -1 instead of 0 [16]. Second, the system is in a pure isospin state of 1, contrary to the pp isospin state which is a mixture of 0 and 1 [16]. An important heating a propellant more effectively than the gamma radiation released in electron-positron annihilation [5]. Consequently, there is more interest in the antiproton-nucleon annihilation processes from a propulsion viewpoint and the electron-positron annihilation is left as a secondary process. It must be pointed out that antiproton-nucleon annihilation must take place at rest for feasible spacecraft propulsion [14]. 3. Antimatter production methods and difficulties 3.1. Natural production It is regarded that celestial bodies in the universe are comprised of matter. However, the opposite might be true. Stars for example might be entirely comprised of antimatter [23]. Unfortunately, the spectrum emitted by these stars is identical to that of stars made from matter, so they cannot be distinguished by current astronomical technologies [24]. Therefore, antimatter bodies cannot be used as of now. Other than that, antimatter is actually produced naturally in the universe, namely around high-energy particle collisions like the ones in the centers of galaxies [25]. They are also produced in environments with sufficing high temperatures where the condition of having a higher particle energy than the energy needed to produce a particle-antiparticle pair is met [14]. Cosmic rays interacting with matter is another source of various antiparticles distinguished by its ability to contain the antiparticles in the cosmic rays themselves [26]. On Earth, \u03b2+ decays of naturally found radioactive isotopes, such as potassium-40, produce positrons [27]. In addition to the interaction of the gamma quanta they yield with matter that also produces positrons discovery to mention here is that antiproton-neutron annihilation can take place in nuclei heavier than Hydrogen only. The lightest alternative in a bubble chamber is liquid deuterium (H-2 isotope) [16]. The antiproton first annihilates on a free neutron, while the proton acts as a spectator. This temporarily forms an antiprotonic deuterium (has an antiproton instead of a proton). Naturally, antiproton-proton annihilation occurs as well with this reaction and proceeds like a regular pp annihilation as explained before [16]. Antiproton-nucleon annihilation process has several advantages over electron-positron annihilation from a practical aspect. First, it supplies much more energy than electron-positron annihilation [16]. Table 2 below lists a comparison of the energies released per particle pair annihilation, noting that both reactions release energy at 100% efficiency. Second, it can be better managed. Antiprotons and their energies can be better controlled before they decay, and the gamma rays they produce after annihilation can be partially controlled by converting it to energy [16]. Third, antiproton annihilations\u2019 products can be better and more efficiently harnessed for propulsion compared to electron-positron annihilations. This is due to the nature of products of each reaction shown in Fig. 7,\u00a0as antiproton annihilations produce fast charged particles, while electron-positron annihilations exhaust gamma rays. The kinetic energy of charged particles released from antiproton annihilations can be collimated for thrust directly by a magnetic nozzle or by [14]. These antielectrons can also be found above thunderstorm clouds [28]. On the other hand, natural radioactivity in the form of \u03b2\u2212 decays creates antineutrinos [29]. <\/p>\n\n\n\n
![\"\"](\"https:\/\/extractech.in\/wp-content\/uploads\/2025\/06\/image-2.png\")
<\/figure>\n\n\n\nIt was also discovered that antiprotons exist in the Van Allen Belts around the Earth [30]. Every second, almost a kilogram of antiprotons enters our solar system, but only a few grams of them make it to the vicinity of Earth [31]. In all the mentioned sources, the antimatter produced is immediately destroyed by contact with nearby matter. That makes it impossible to harvest naturally produced antimatter, or at least in the near future. 3.2. Artificial production Scientists have already successfully produced, captured, cooled, and stored some antihydrogen atoms [32]. Nevertheless, even with substantial technological developments, there is still a chance that generating and storing enough antimatter for propulsion is not possible [33]. This is because it requires huge amounts of energy input, at least an amount equal to the rest energy of the created particle\/antiparticle pairs, and usually (like for antiprotons) tens of thousands to millions of times more [14]. On top of that, most proposed antimatter rocket designs require a relatively large amount of antimatter. Around 1MeV of energy is required to produce an electron-positron couple, while a proton-antiproton couple and neutron antiproton couple, require about 2GEV of energy, which raises a demand for larger particle accelerator than the ones existing [3]. Techniques and methods either proposed or developed are still vital to develop a future antimatter production line with sufficient capacity [34]. Realistically, it only makes sense to try to make, stockpile, and use antihydrogen, for two reasons [16]. First, neutral antimatter is ultimately needed for easier and better handling, so antiprotons or positrons cannot be used alone [16]. Their individual electromagnetic properties, owing to being charged, are still essential for controlling them, so antineutrons cannot be used as well. Second, it would be too expensive and energy inefficient to produce any larger antimatter atom [16]. In addition, antihydrogen atoms should be made cryogenically and stored in the form of microscopic, charged antihydrogen flakes at very low temperatures. This is the best, interim solution for antimatter production that enables scientists to handle antimatter and study it using the current technology. There are many ideas proposed as to how antihydrogen can be made [35,36]. Among these are: 1. Bombarding an atom with an antiproton travelling at a relativistic speed to force create an electron-positron pair (positronium). Then there would be a slight chance that the antiproton pairs with the positron and ejects the electron forming an antihydrogen atom [37]. 2. Robert Forward once came up with the idea of antimatter plants in space that are powered by the Sun [38]. His idea was to build a 100 km collector array to obtain power input from the Sun\u2019s radiation. This could provide ten terawatts of power, sufficient to run multiple antimatter factories at full capacity and produce one gram of antimatter per day [38]. 3. An idea from Bickford was to make a magnetic shovel from a plasma magnet that direct charged particles and trap them over long distances. For instance, if placed in the equatorial orbit around the Earth, it can capture the antiparticles occurring in the Van Allen\u2019s belt. A possible configuration is to use RF (radiofrequency) coils made from high-temperature superconductors to generate a magnetic field inside them that concentrates the incoming antiprotons from the radiation belt and captures them [3]. 4. Another possible way is to extremely cool antiprotons and positrons and combine them to form antihydrogen, but this requires that antiprotons and positrons are made and managed first. It might even be possible to further condense the antihydrogen to form antihydrogen crystals to make it easier to store and handle for propulsion purposes, but this would be the next stage [39,40]. 5. Two more methods are proposed in [41]. The first approach involves collecting antiprotons and pions generated by high-energy proton collisions with a heavy-element target. While more pions than antiprotons are initially produced, the pions are redirected to collide with the same or another heavy target. These pion-heavy nucleus collisions have a higher likelihood of producing antiprotons, thereby significantly boosting their yield. The second approach utilizes a recirculating electron\/positron collider designed to produce repeated collisions near a resonance optimized for antiproton generation. By employing beam wigglers, similar to those in free electron lasers, this method greatly enhances the number of interactions, leading to a proportional increase in antiproton production. 4. Antimatter storage and control Another major difficulty with antimatter is storing it and controlling it. To begin with, it has already been shown that storing solid or liquid antimatter in contact with any state of matter is impossible [42]. This is owing to the prohibitive energy production rates from annihilation with matter, causing loss of energy in a significant manner. It basically means that antimatter keeps on annihilating with matter at rapid rates upon the smallest contact with it. Therefore, the only and best option is to use magnetic, electrostatic, or electromagnetic suspension of solid antimatter in a vacuum [42]. The solid antimatter being frozen pellets of antihydrogen. Some examples of such systems include Penning or Paul traps. The concept depends on the property of spin magnetic moment of antimatter. The magnetic and electric fields exert a force on the antimatter, directing it away from any matter and preventing its contact with the sides of the storage box. This system yields a very high storage density for the antihydrogen fuel [5]. This is not to say that this is the perfect solution as there are still practical hurdles to be overcome. Annihilation could occur between vaporized antiatoms with matter on the surface of the container (magnetic coils for example) or between vaporized matter entering the confinement chamber. The former imposes a serious technical difficulty that has not yet been solved because the antimatter used is frozen antihydrogen with an extremely low freezing point [7]. The latter is preventable with proper design and materials choice that maintains absolute vacuum within the chamber [43,44]. <\/p>\n\n\n\n
![\"\"](\"https:\/\/extractech.in\/wp-content\/uploads\/2025\/06\/image-3.png\")
<\/figure>\n\n\n\nCurrently available electromagnetic traps include PenningMalmberg traps and Ioffe-Pritchard which have been used to confine matter and have recently been used to trap antimatter in the European Council for Nuclear Research (CERN), shown in Fig. 8 (a) and (b) [45]. These traps are also used as production sites of antihydrogen by combining positrons and antiprotons within the trap itself [46,47]. They confine particles in three dimensions by applying magnetic fields for radial confinement and electric fields, from voltages applied to a series of cylindrical electrodes, along the axis of a solenoid. So, radial trapping is achieved by magnetic fields and axial trapping is done by electric fields. These traps can only store a couple of antihydrogen atoms with the maximum duration of trapping achieved being 1000 second\u00a0Also, extremely high energies and voltages are needed to acquire the high electromagnetic fields for the traps\u2019 operation as seen in the ALPHA experiment [50,51]. At the same time, temperatures of lower than 375 mK must be maintained within the trap for sufficient trapping efficiency, meaning that no heating from the wires should reach the inner vacuum. Looking into the currently available methods of storage, a huge gap is noticed in the capacity of H atoms storage with the limit being a couple of atoms. In addition, scientists are only trapping them for very short durations before annihilating them by turning off the electrostatic and magnetic fields, so that they are detected [52]. The inability to detect antimatter atoms unless they are annihilated and then the products detected is another serious defect in antimatter research procedures that is immensely slowing down progress in this area.<\/p>\n\n\n\n
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Pushing the boundaries of science, we are at the forefront of antimatter research\u2014unlocking new potentials for energy, medical applications, and scientific discovery. Our antimatter initiatives aim to revolutionize energy storage and propulsion systems, paving the way for a new era of technological innovation. Over the past of space exploration, chemical spacecraft propulsion systems have proven […]<\/p>\n","protected":false},"author":1,"featured_media":623,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[12],"tags":[],"class_list":["post-590","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-case-studies"],"_links":{"self":[{"href":"https:\/\/extractech.in\/en\/wp-json\/wp\/v2\/posts\/590","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/extractech.in\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/extractech.in\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/extractech.in\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/extractech.in\/en\/wp-json\/wp\/v2\/comments?post=590"}],"version-history":[{"count":1,"href":"https:\/\/extractech.in\/en\/wp-json\/wp\/v2\/posts\/590\/revisions"}],"predecessor-version":[{"id":596,"href":"https:\/\/extractech.in\/en\/wp-json\/wp\/v2\/posts\/590\/revisions\/596"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/extractech.in\/en\/wp-json\/wp\/v2\/media\/623"}],"wp:attachment":[{"href":"https:\/\/extractech.in\/en\/wp-json\/wp\/v2\/media?parent=590"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/extractech.in\/en\/wp-json\/wp\/v2\/categories?post=590"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/extractech.in\/en\/wp-json\/wp\/v2\/tags?post=590"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
- Radiative capture yielding a photon plus a positronium, a protonium, or a nucleonium in the case of electron\u2013positron interaction, antiproton\u2013proton interaction, or interaction with heavier particles, respectively. <\/strong><\/li>\n\n\n\n