Hello! In this article, I tried to briefly describe the properties of antimatter, methods of its use in astronautics, and completely from scratch designed and calculated a propulsion system based on antiparticles.
Introduction
To explore outer space, humanity needs more powerful propulsion systems compared to the current ones. Let’s take the flight to Mars as an example. Under current conditions, such a flight can take more than six months in one direction only. During this time, people on the ship will receive a critical dose of cosmic radiation. Methods of protection against this have not yet been created, so the only way out of the situation is to move at greater speed. In order to develop greater speed relative to current engines, a more advanced engine with a higher specific impulse is required. One of these engines may be an antimatter engine.
Antimatter is matter made up of antiparticles. A series of elementary particles that have the same mass, but differ from each other in the signs of all other interaction characteristics. For example, an electric charge. When antimatter collides with matter, it annihilates, releasing all the mass energy of both matter and antimatter. The history of the discovery of the existence of antimatter began when Einstein formed the energy equation; for a moving particle, the equation has a different form and takes into account its momentum.
E2 = p2 *c2 + m2 *c2
Engine design
You need to understand that antiparticles have an extremely high density. Because of this, their annihilation can literally tear apart the engine. To avoid this, a damper is needed. (damper is a device used to dampen or prevent mechanical vibrations that occur in machines and mechanisms during their operation).
Let’s talk in more detail about the annihilation of antiparticles. Antiproton annihilation is an interaction process at the level of the quark structure of the nucleus. A proton consists of a pair of quarks with a charge of +2/3 and one quark with a charge of -1/3. An antiproton, accordingly, is its complete opposite: a pair of antiquarks -2/3 and one antiquark with a charge of +1/3. When the antiproton annihilates, an energy of 1.88 gigaelectronvolts is released. This energy is converted into the kinetic energy of charged and neutral pi mesons. Accordingly, the electromagnetic nozzle is also an extremely necessary part of our engine. With its help, we (in theory) will be able to direct charged pi-mesons and, thereby, create jet thrust.
The next detail is the duoplasmatron. (Duoplasmatron is a type of ion source). By ionizing the hydrogen that will be taken from the tanks, it will become our source of protons for annihilation.
The question remains: where and how will we store antiprotons for the subsequent reaction? Charged antimatter particles, such as positrons and antiprotons, can be stored in so-called Penning traps. They are like tiny particle accelerators. Inside them, particles move in a spiral while magnetic and electric fields keep them from colliding with the walls of the trap. However, Penning traps do not work for neutral particles like antihydrogen. Because they have no charge, these particles cannot be confined by electric fields. They are held in Ioffe traps, which work by creating a region of space where the magnetic field becomes stronger in all directions.
Penning trap diagram:
You may wonder: “How will we fly if the antiparticles are quite unstable and currently cannot be stored for more than half an hour?” You can take several answer options. The first is that we will wait until scientists can extend the storage of antiparticles in magnetic traps by days. The second is to use all the fuel within this very half hour. In this case, together with the launch of the engine into orbit and its docking with the ship, there will be extremely little time left. And despite the damper, the entire ship can be destroyed by the force of annihilation of a relatively large number of antiparticles, in a relatively short period of time. Therefore, I prefer the first option.
Characteristics:
P=w/g * W+F(Pk-Po)=3000kN
Pbeat=P/w=20.000.000 m/s
P-thrust, w-weight per second flow rate, W-change in gas velocity, F-nozzle exit area, Pk-gas pressure in the nozzle exit section, Po-ambient pressure.
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Height ~ 10 meters
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Weight ~ 1.5 tons
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Diameter = 2-3 meters
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The main material is tungsten.
A little clarification. We know that in the atmosphere the thrust of such an engine is zero, which means the pressure difference in the nozzle and the environment is 15%. We take the weight per second consumption as 47 ng per second. we take the change in gas speed (in our case, the products of annihilation of antimatter and matter) as 196000000, which is the speed acquired [“газ”] upon annihilation. Now we can calculate 85% of the thrust, it will be equal to the weight per second divided by the acceleration of free fall and multiplied by the change in speed [“газ”]. We get 2400000N, from this we can get the total thrust and cross-sectional area of the exit nozzle. the nozzle exit area will be equal to 15% of the total thrust, this is equal to 400000N, divided by the pressure, then the nozzle exit area will be 4.4 cm^2. We can get the specific impulse by dividing the total thrust of 3000000N by the weight per second, and we get 23000000.
Conclusion
In conclusion, I cannot help but note that the generation of antimatter, its storage and the creation of jet propulsion are the most complex technical tasks. Fortunately, it is possible to solve them – no laws of physics contradict this. By the way, a flight to the star closest to the sun (Proxima Centauri) using such an engine will take no more than 20 years. Compared to thousands of years of flight on current chemical engines, this is an acceptable period.
From available sources of information, I found out that about 12 mg of antiprotons will be needed to fly to Mars. At the highest speed of 120,000 km/s. Based on calculations, if 49 ng of antiprotons are supplied every second, this speed will be achieved in 1.16 days. The entire flight will take about 5-6 days.
And I present the result of the work, namely a 3D model of the engine.
If you look from left to right, the first is the magnetic nozzle, with its help we will direct charged pi-mesons, then the Penning trap for storing antiprotons, the duoplasmatron for ionizing hydrogen, and immediately behind it is a tank with hydrogen. And all this surrounds the damper.
Theoretical part
History of the discovery of antiparticles
In 1927, English theorist Paul Dirac provided a sound theoretical basis for the concept of electron spin. To describe the behavior of an electron in an electromagnetic field, Dirac introduced the special theory of relativity into quantum mechanics by the German-born physicist Albert Einstein. Dirac’s relativistic theory showed that the electron must have spin and a magnetic moment, but it also did something that seemed strange. The basic equation describing the allowable energies for an electron would allow two solutions, one positive and one negative. The positive solution apparently described normal electrons. The negative solution was more of a mystery; it seemed to describe electrons with a positive rather than a negative charge.
The mystery was solved in 1932 when American physicist Carl Anderson discovered a particle called a positron. Positrons are very similar to electrons: they have the same mass and the same spin, but have opposite electrical charges. Thus, positrons are the particles predicted by Dirac’s theory, and they were the first of the so-called antiparticles discovered. Dirac’s theory, in fact, applies to any subatomic particle with a spin of 1/2; therefore, all particles with spin 1/2 must have corresponding antiparticles. However, matter cannot be created from either particles or antiparticles. When a particle meets its corresponding antiparticle, they disappear in an act of mutual annihilation known as annihilation.
Using particle accelerators, physicists can simulate the effects of cosmic rays and create high-energy collisions. In 1955, a team led by Italian-born scientist Emilio Segre and American Owen Chamberlain found the first evidence for the existence of antiprotons in high-energy proton collisions produced by the Bevatron accelerator at Lawrence Berkeley National Laboratory in California. Shortly thereafter, another team working on the same accelerator discovered the antineutron.
Properties and structure of antiparticles
Antiparticles differ from particles by replacing all charges (electric, baryon, lepton, quark flavors) with the opposite one. A number of characteristics of the particle and antiparticle coincide (mass, spin). The relationship between the characteristics of particles and antiparticles is shown in the table.
Characteristic |
Particle |
Antiparticle |
Weight |
M |
M |
Electric charge |
+(-)Q |
-(+)Q |
Spin |
J |
J |
Magnetic moment |
+(-) |
-(+) |
Baryon number |
+B |
-B |
Lepton number |
+Le+Lμ+Lτ |
-Le-Lμ-Lτ |
Weirdness |
+(-)s |
-(+)s |
Charm |
+(-)c |
-(+)c |
Bottomness |
+(-)b |
-(+)b |
Topness |
+(-)t |
-(+)t |
Isospin |
I |
I |
Isospin projection |
+(-)I3 |
-(+)I3 |
Parity |
+(-) |
-(+) |
Lifetime |
T |
T |
Decay scheme |
|
Charge conjugate |
Extraction methods
Basically, cosmic rays consist of particles that are “normal” in deep space: protons, alpha particles and electrons. But sometimes they contain something unusual, for example, antimatter particles – antiprotons and positrons. Where can they come from if the entire Universe consists of matter and not antimatter?
First, antiparticles, especially positrons, can be born near some astrophysical object that operates as a cosmic electron accelerator, such as a pulsar. Then he can pick up and accelerate to high energies not only electrons, but also positrons. Such positrons are considered a full component of primary cosmic rays. Even if there were no antiparticles in the primary cosmic rays, they will appear when they collide with interstellar matter. Such particles are called secondary particles because they arise as a by-product of the propagation of primary cosmic rays in the galaxy. This is the most standard, “most boring” source of positrons and antiprotons in space.
Antimatter can be produced in particle accelerators. Antiparticles, for example antiprotons, are obtained as follows: a beam of protons is collided with a metal target, as a result of the collision many particles are formed, including the antiprotons we need. The next step is to isolate the antiprotons using a magnetic or electric field.
Positrons, according to the theory of Julian Schwinger (Nobel laureate), can appear in the vacuum of space, under the influence of a strong electric field in the form of an electron-positron pair, by polarizing the vacuum.
Well, that’s probably all. 🙂
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