A huge electric propulsion engine with record-breaking performance passed a ground test under a load exceeding the nominal value. The newcomer combines decent traction with economy. And this allows us to hope for a new round in the development of the space industry.
The ion drive is well known to us from science fiction novels. The principle of its operation is the ionization of gas and its acceleration by an electrostatic field. Ions provide much less thrust than chemical fuels, so such an engine would not be able to give the rocket even the first space velocity. But if you launch it in space, then it can literally work for years on end, accelerating the ship to unprecedented speeds.
Some space missions have already used such engines, including the Japanese spacecraft Hayabusa (2005, flight to the asteroid Itokawa), as well as the US spacecraft Dawn, which launched in September 2007 to the asteroids Vesta and Ceres.
But new model engine called VASIMR (Variable Specific Impulse Magnetoplasma Rocket) will be hundreds of times more powerful than previous ion engines due to the use of not standard metal gratings in the process of accelerating argon ions, but a radio frequency generator that does not come into physical contact with the gas, like gratings.
Ad Astra Rocket Company has tested the most powerful plasma rocket engine to date. The VASIMR VX-200 (which we talked about not so long ago) ran at 201kW in a vacuum chamber, breaking the 200kW mark for the first time. The test also confirmed that the small-scale prototype VASIMR (Variable Specific Impulse Magnetoplasma Rocket) is capable of operating on full power. “This is the most powerful plasma rocket in the world today,” says former astronaut and Ad Astra CEO Franklin Chang-Diaz.
The company entered into an agreement with NASA to conduct an engine performance test on the International Space Station (ISS) in 2013. It will produce periodic "boosts" of the station, which is constantly decreasing due to interaction with the atmosphere. At present, such operations are carried out by small-thrust engines of ships, consuming about 7.5 tons of rocket fuel per year. Cheng-Diaz claims that by reducing this amount to 0.3 tons, VASIMR will save NASA millions annually.
But Ad Astra has more ambitious plans. For example, missions to Mars on high speed. A 10MW or 20MW VASIMR would be able to get humans to the red planet in 39 days, while conventional rockets would take six months, if not more. The shorter the journey, the less the astronauts will be exposed to cosmic radiation, which is a significant obstacle.
Innovation ion engine can also be adapted for larger payloads in robotic missions, although flight speed will be reduced. Cheng-Diaz has been working on the development of the VASIMR concept since 1979, long before the business was founded in 2005. The technology involves the use of radio waves to heat gases (hydrogen, argon, neon) to form a high-temperature plasma. Magnetic fields push it out of the engine, which creates jet thrust. As a consequence of the high speed that is achieved by the continuous process of its build-up, much less fuel than for conventional engines. In addition, the VASIMR design eliminates the physical contact of the electrodes with the plasma, which means that the service life is extended.
How VASIMR works in the test chamber can be seen in this video. True, it refers to a long-standing test, during which the device consumed only 179 kilowatts. Of these, 30 kW were used in the first part of the engine to create plasma, and 149 kW were used to heat and accelerate it in the second chamber.
It is worth recalling the American interplanetary probe Dawn, which launched in the fall of 2007 (it will arrive at its first target, Vesta, in 2011). For acceleration to the asteroid belt, Dawn uses three ion thrusters, each of which develops a maximum thrust of 90 millinewtons.
“This is identical to the weight of one piece of paper from a notebook,” NASA figuratively explains. What, you ask, is the point? The fact is that “ionics” are about 10 times more effective than chemical ones. rocket engines. In particular, the specific impulse of the devices standing on the Dawn is 3100 seconds.
Therefore, 425 kilograms of the working fluid (xenon) will be enough for them for 2100 days of work. Even if Dawn's acceleration is invisible to the eye, the total speed increase over the entire mission will be about 10 kilometers per second.
And the device itself turned out to be relatively light (a ton and a quarter). Therefore, for its launch from Earth, a rocket of a smaller class (Delta II) was needed, and therefore cheaper, in comparison with the one that would be required to lift a hypothetical asteroid explorer built on the basis of chemical engines into orbit.
The specific impulse of the VX-200 is about 5000 seconds. In general, it can change, which is reflected in the name of the device. Greater efficiency can be obtained at low thrust, less - at maximum.
So you can vary the mode of operation of the main engine depending on the objectives of the mission of the spacecraft. Somewhere you can afford to spend a little more working fluid, but reduce the flight time, somewhere, on the contrary, complete the task for a longer period, but with a minimum consumption of "fuel", which means - minimum weight device.
It should be noted here that VASIMR claims to be some kind of intermediate option for creating thrust in space. Between chemical boosters (powerful but voracious) and extremely tiny electric rocket engines, which can be much more economical than even the VX-200, but the thrust will be only a fraction of a gram.
VASIMR has another advantage over competitors from the camp of electric propulsion in general: in it, the plasma does not come into contact with the details of the device at any point, but only contacts with the fields.
This means that the device from Ad Astra will be able to work for many months and even years without structural degradation - what is needed to accelerate spacecraft on their way to the depths of the solar system or correct the orbit of satellites. Classical ion rocket engines have a sore point - the erosion of electrode grids. VASIMR simply does not have those.
Ad Astra Rocket has rich plans for VASIMR in a number of projects. Thus, under an agreement with the US space agency in 2013, the flight version of the VX-200, named VF-200-1, should be tested on the ISS. The device currently being developed will be based on the general design of the VX-200, but will consist of two virtually parallel engines of 100 kilowatts each.
(Interestingly, Ad Astra Rocket is negotiating the delivery of VF-200-1 to the station using a private carrier from SpaceX or Orbital Sciences).
VF-200-1 will try to raise the station’s orbit, which regularly “sags” due to weak braking in the remnants of the atmosphere, even at a 400-kilometer altitude. The VF-200-1 will turn on for a short time (several minutes) sporadically. And since the power taken by it from the network is very large, the engine must consume the energy stored in special batteries, which, in turn, during pauses in the operation of the plasma accelerator will be gradually recharged from the solar panels of the ISS.
If the test is successful, the station may be transferred to this method of raising the orbit. And that promises big savings. After all, the current version of orbit lifting (with the help of chemical engines of supply transport ships) means the consumption of 7.5 tons of fuel per year, while VASIMR will require 300 kilograms of argon annually for the same target. The prospects for technology are even more tempting.
Based on one or more VF-200-1, the company believes it is possible to build an unmanned truck that will transport big loads from low Earth orbit to lunar orbit. These engines would be powered by solar panels.
For such a device, most likely, an on-board nuclear power plant would be required - solar panels of the required power would come out simply monstrously large.
Experts have been talking about the fact that electric rocket engines for long-range missions “request” nuclear fuel for a long time. There are no fundamental and insoluble difficulties in the construction of such a generator now.
Not all questions regarding the intricacies of the work of the VASIMR itself have been removed yet. Scientists have to increase the overall efficiency of the system and find The best way getting rid of excess heat dissipated by such an engine. But in general, the technology is already approaching the stage when exclusively ground-based experimental facilities should give rise to modifications intended to be sent into orbit. Chan-Diaz and his colleagues believe that commercial versions of VASIMR-type engines may appear on the market in 2014.
Man went into space thanks to liquid and solid propellant rocket engines. But they also called into question the effectiveness of space flights. In order for a relatively small one to at least "catch" on it, they are installed on top of a launch vehicle of impressive size. And the rocket itself, in fact, is a flying tank, the lion's share of the weight of which is reserved for fuel. When all of it is used up to the last drop, a meager supply remains on board the ship.
In order not to fall to the Earth, it periodically raises its orbit with impulses. Fuel for them - about 7.5 tons - is delivered by automatic ships several times a year. But such refueling is not expected on the way to Mars. Isn't it time to say goodbye to outdated circuits and pay attention to a more advanced ion engine?
In order for it to work, insane amounts of fuel are not required. Only gas and electricity. Electricity in space is generated by capturing the light emitted from the sun by solar panels. The farther from the star, the less their power, so you will have to use more and the gas enters the primary combustion chamber, where it is bombarded by electrons and ionized. The resulting cold plasma is sent to warm up, and then - to the magnetic nozzle, for acceleration. The ion engine ejects hot plasma from itself at speeds inaccessible to conventional rocket engines. And it gets the boost it needs.
The principle of operation is so simple that you can assemble a demonstration ion engine with your own hands. If the pinwheel-shaped electrode is previously balanced, placed on the tip of a needle and a high voltage is applied, a blue glow will appear at the sharp ends of the electrode, created by electrons escaping from them. Their expiration will create a weak reactive force, the electrode will begin to rotate.
Alas, ion thrusters have such meager thrust that they cannot lift a spacecraft from the surface of the Moon, not to mention a ground launch. This can be most clearly seen if we compare the two ships going to Mars. A liquid-propellant ship will begin its flight after a few minutes of intense acceleration and spend slightly less time decelerating near the Red Planet. The ship with ion engines will accelerate for two months in a slowly unwinding spiral, and the same operation awaits it in the vicinity of Mars ...
And yet, the ion engine has already found its application: it is equipped with a number of unmanned spacecraft sent on long-term reconnaissance missions to the near and far planets of the solar system, to the asteroid belt.
The ion engine is the same turtle that overtakes the swift-footed Achilles. Having used up all the fuel in a matter of minutes, liquid engine falls silent forever and becomes a useless piece of iron. And plasma can work for years. It is possible that they will be equipped with the first spacecraft, which will go to the nearest star to the Earth at sub-light speed. It is assumed that the flight will take only 15-20 years.
March 9th, 2013
The problem of movement in space has been facing mankind since the beginning of orbital flights. A rocket taking off from the ground consumes almost all of its fuel, plus the charges of boosters and stages. And if the rocket can still be torn off the ground, filling it with a huge amount of fuel, at the cosmodrome, then in outer space there is simply nowhere and nothing to refuel. But after entering orbit, you need to move on. And there is no fuel.
And this is the main problem of modern astronautics. It is still possible to throw a ship into orbit with a supply of fuel to the moon, under this theory, plans are being made to create a base for refueling "long-range" on the moon spaceships flying to Mars, for example. But it's all too complicated.
And the solution to the problem was created a long time ago, back in 1955, when Aleksey Ivanovich Morozov published an article "On plasma acceleration by a magnetic field." In it, he described the concept of a fundamentally new space engine.
Ion plasma engine device
Operating principle plasma engine consists in the fact that non-burning fuel acts as a working fluid, as in jet engines, but a stream of ions accelerated by a magnetic field to insane speeds.
The source of ions is gas, usually argon or hydrogen, the gas tank is at the very beginning of the engine, from there the gas is supplied to the ionization compartment, cold plasma is obtained, which is heated in the next compartment by means of ion cyclotron resonant heating. After heating, the high-energy plasma is fed into the magnetic nozzle, where it is shaped into a stream by magnetic field, accelerates and is ejected into environment. This is how traction is achieved.
Since then, plasma engines have come a long way and have been divided into several main types, these are electrothermal engines, electrostatic engines, high-current or magnetodynamic engines, and impulse engines.
In turn, electrostatic engines are divided into ion and plasma (particle accelerators on a quasi-neutral plasma).
In this article we will write about modern ion engines and them promising developments, since in our opinion the future of the space fleet is behind them.
The ion engine uses either xenon or mercury as fuel. The first ion thruster was called the gridded electrostatic ion thruster.
The principle of its operation is as follows:
The ionizer is fed xenon, which is neutral in itself, but ionizes when bombarded by high-energy electrons. Thus, a mixture of positive ions and negative electrons is formed in the chamber. To “filter out” the electrons, a tube with cathode grids is brought into the chamber, which attracts electrons to itself.
Positive ions are attracted to the extraction system, which consists of 2 or 3 grids. Between Grids Supported a big difference electrostatic potentials (+1090 volts on the inside against - 225 on the outside). As a result of ions falling between the grids, they are accelerated and thrown into space, accelerating the ship, according to Newton's third law.
Russian ion engines. The cathode tubes directed towards the nozzle are clearly visible on all
The electrons trapped in the cathode tube are ejected from the engine at a slight angle to the nozzle and ion flow. This is done for two reasons:
Firstly, so that the hull of the ship remains neutrally charged, and secondly, so that the ions "neutralized" in this way are not attracted back to the ship.
For the ion engine to work, only two things are needed - gas and electricity. With the first, everything is just fine, the engine of the American interplanetary apparatus Dawn, which was launched in the fall of 2007, will need only 425 kilograms of xenon to fly for almost 6 years. For comparison, 7.5 tons of fuel is spent every year to correct the ISS orbit using conventional rocket engines.
One bad thing - ion thrusters have very little thrust, on the order of 50-100 millinewtons, which is absolutely insufficient when moving in the Earth's atmosphere. But in space, where there is practically no resistance, the ion engine can reach significant speeds during long acceleration. The total speed increase over the entire duration of the Dawn mission will be on the order of 10 kilometers per second.
Ion thruster test for Deep Space ship
Recent tests conducted by the American company Ad Astra Rocket, carried out in a vacuum chamber, showed that their new Variable Specific Impulse Magnetoplasma Rocket VASIMR VX-200 can produce thrust as early as 5 Newtons.
The second issue is electricity. The same VX-200 consumes 201 kW of energy. solar panels such an engine is simply not enough. Therefore, it is necessary to invent new ways of obtaining energy in space. There are two ways here - refueling batteries, for example, tritium, launched into orbit along with the ship, or an autonomous nuclear reactor, which will power the ship throughout the flight.
Back in 2006, the European Space Agency and the Australian National University (Australian National University) successfully tested a new generation of space ion thrusters, reaching record levels.
Engines in which charged particles are accelerated in an electric field have long been known. They are used for orientation, orbit correction on some satellites and interplanetary vehicles, and in a number of space projects (both already implemented and just conceived - read, and) - even as marching ones.
With them, experts associate the further development of the solar system. And although all varieties of so-called electric rocket engines are much inferior to chemical ones in maximum thrust (grams versus kilograms and tons), they are radically superior in efficiency (fuel consumption per gram of thrust per second). And this economy (specific impulse) is directly proportional to the speed of the ejected jet.
So, in an experimental engine called "Dual-Stage 4-Grid - DS4G", built under an ESA contract in Australia, this speed reached a record 210 kilometers per second.
This, for example, is 60 times higher than the exhaust velocity of good chemical engines, and 4-10 times higher than that of the old "ion engines".
As it is clear from the name of the development, this speed was achieved by a two-stage ion acceleration process using four successive gratings (instead of the traditional one stage and three gratings), as well as high voltage- 30 kilovolts. In addition, the divergence of the output jet beam was only 3 degrees, compared to about 15 degrees for previous systems.
And here is the information of the last days.
The ion engine (ID) works simply: the gas from the tank (xenon, argon, etc.) is ionized and accelerated by an electrostatic field. Since the mass of the ion is small, and it can receive a significant charge, the ions fly out of the engine at speeds up to 210 km/s. Chemical engines can achieve ... no, not anything like that, but only twenty times less exhaust velocity of combustion products only in exceptional cases. Accordingly, the consumption of gas in comparison with the consumption of chemical fuel is extremely small.
That is why such “long-range” probes as Hayabusa, Deep Space One and Dawn have been fully or partially working on ID. And if you are going not just to fly by inertia to distant celestial bodies, but also to actively maneuver near them, then you cannot do without such engines.
In 2014, ion thrusters celebrate their 50th anniversary in space. All this time, the problem of erosion could not be solved even in the first approximation. (Here and below ill. NASA, Wikimedia Commons.)
Like all good things, the ID likes to be fed: up to 25 kW of energy is needed for one newton of thrust. Let's imagine that we were assigned to launch a 100-ton spacecraft to Pluto (forgive us for dreaminess!). Ideally, even for Jupiter, we need 1,000 newtons of thrust and 10 months, and to Neptune at the same thrust - a year and a half. In general, let's not talk about Pluto, otherwise it's somehow sad ...
Well, to get these so far speculative 1,000 newtons, we need 25 megawatts. In principle, nothing technically impossible - a 100-ton ship could take a nuclear reactor. Incidentally, NASA and the US Department of Energy are currently working on the Fission Surface Power project. True, we are talking about bases on the Moon and Mars, and not about ships. But the mass of the reactor is not so high - only five tons, with dimensions of 3 × 3 × 7 m ...
Well, okay, dreamed and that's enough, you say, and immediately remember the ditty, allegedly invented by Leo Tolstoy during the Crimean War. After all, such a large flow of ions passing through the engine (and this is a key obstacle) will cause it to erode, and much faster than in ten months or a year and a half. Moreover, this is not a problem of choosing a structural material - both titanium and diamond will be destroyed under such conditions, but an integral part of the design of an ion engine per se.
Adapted from Gizmag. and http://lab-37.com
Do you know that it is active in Russia, or, for example, that it may soon appear The original article is on the website InfoGlaz.rf Link to the article from which this copy is made -
Space engines of the future
Creation of the ion engine
We keep talking about types of engines.
The problem of movement in space has been facing mankind since the beginning of orbital flights. A rocket taking off from the ground consumes almost all of its fuel, plus the charges of boosters and stages. And if the rocket can still be torn off the ground, filling it with a huge amount of fuel, at the cosmodrome, then in outer space there is simply nowhere and nothing to refuel. But after entering orbit, you need to move on. And there is no fuel.
And this is the main problem of modern astronautics. It is still possible to throw a ship into orbit with a supply of fuel to the moon, under this theory plans are being made to create a refueling base on the moon for "long-range" spacecraft flying, for example, to Mars. But it's all too complicated.
And the solution to the problem was created a long time ago, back in 1955, when Aleksey Ivanovich Morozov published an article "On plasma acceleration by a magnetic field." In it, he described the concept of a fundamentally new space engine.
Ion plasma engine device
Operating principle plasma engine is that the working fluid is not burning fuel, as in, but a stream of ions accelerated by a magnetic field to insane speeds.
The source of ions is gas, usually argon or hydrogen, the gas tank is at the very beginning of the engine, from there the gas is supplied to the ionization compartment, cold plasma is obtained, which is heated in the next compartment by means of ion cyclotron resonant heating. After heating, high-energy plasma is fed into the magnetic nozzle, where it is formed into a flow by means of a magnetic field, accelerated and released into the environment. This is how traction is achieved.
Since then, plasma engines have come a long way and have been divided into several main types, these are electrothermal engines, electrostatic engines, high-current or magnetodynamic engines, and impulse engines.
In turn, electrostatic engines are divided into ion and plasma (particle accelerators on a quasi-neutral plasma).
In this article we will write about modern ion engines and their promising developments, since, in our opinion, the future of the space fleet is behind them.
The ion engine uses either xenon or mercury as fuel. The first ion thruster was called the gridded electrostatic ion thruster.
The principle of its operation is as follows:
The ionizer is fed xenon, which is neutral in itself, but ionizes when bombarded by high-energy electrons. Thus, a mixture of positive ions and negative electrons is formed in the chamber. To “filter out” the electrons, a tube with cathode grids is brought into the chamber, which attracts electrons to itself.
Positive ions are attracted to the extraction system, which consists of 2 or 3 grids. A large difference in electrostatic potentials is maintained between the grids (+1090 volts on the inside versus - 225 on the outside). As a result of ions falling between the grids, they are accelerated and thrown into space, accelerating the ship, according to Newton's third law.
Russian ion engines. The cathode tubes directed towards the nozzle are clearly visible on all
The electrons trapped in the cathode tube are ejected from the engine at a slight angle to the nozzle and ion flow. This is done for two reasons:
Firstly, so that the hull of the ship remains neutrally charged, and secondly, so that the ions "neutralized" in this way are not attracted back to the ship.
For the ion engine to work, only two things are needed - gas and electricity. With the first, everything is just fine, the engine of the American interplanetary apparatus Dawn, which was launched in the fall of 2007, will need only 425 kilograms of xenon to fly for almost 6 years. For comparison, 7.5 tons of fuel is spent every year to correct the ISS orbit using conventional rocket engines.
One bad thing - ion engines have very little thrust, on the order of 50-100 millinewtons, which is absolutely insufficient when moving in the Earth's atmosphere. But in space, where there is practically no resistance, the ion engine can reach significant speeds during long acceleration. The total speed increase over the entire duration of the Dawn mission will be on the order of 10 kilometers per second.
Ion thruster test for Deep Space ship
Recent tests conducted by the American company Ad Astra Rocket, carried out in a vacuum chamber, showed that their new Variable Specific Impulse Magnetoplasma Rocket VASIMR VX-200 can produce thrust as low as 5 Newtons.
The second issue is electricity. The same VX-200 consumes 201 kW of energy. Solar panels are simply not enough for such an engine. Therefore, it is necessary to invent new ways of obtaining energy in space. There are two ways here - refueling batteries, for example, tritium, launched into orbit along with the ship, or an autonomous nuclear reactor, which will power the ship throughout the flight.
In the second case, in space conditions and its low temperatures more interesting is the project of a ship with a thermonuclear reactor on board, but so far NASA is developing only a nuclear reactor.
These studies are being carried out as part of the Prometheus project. NASA plans to launch a nuclear probe into the solar system, equipped with powerful ion engines powered by an onboard nuclear reactor.
Last test video ion engine VX-200.
The European Space Agency has tested a ramjet ion thruster using air from the surrounding atmosphere as a working fluid. It is assumed that small satellites with such an engine will be able to be in orbits with an altitude of 200 kilometers or less almost indefinitely, according to a press release from the agency.
The principle of operation of ion engines is based on the ionization of gas particles and their acceleration using an electrostatic field. Gas particles in such engines are accelerated to significantly high speeds, than in chemical engines, which is why ion engines have a much higher specific impulse and consume less fuel. But the ion engine has and important disadvantage- extremely low thrust compared to chemical engines. Because of this, they are rarely used in practice, mainly on small devices. For example, such engines are used on the Dawn probe, currently orbiting the dwarf planet Ceres, and will be used in the BepiColombo mission, which is due to go to Mercury at the end of 2018.
Like chemical propulsion, the ion propulsion systems currently in use use a fuel supply, typically xenon. But there is also the concept of direct-flow ion engines, which, however, has not yet been used on vehicles flying into space. Its difference lies in the fact that it is proposed to use as a working fluid not the final supply of gas loaded into the tank before launch, but air from the Earth's atmosphere or another atmospheric body.
Engine operation diagram
ESA-A. Di Giacomo
It is assumed that a relatively small apparatus with such an engine will be able to be practically unlimited in low orbits with an altitude of about 150 kilometers, compensating for atmospheric braking by the thrust of the engine operating on air entering it from the atmosphere. In 2009, ESA launched the GOCE satellite, which was able to stay in a 255-kilometer orbit for almost five years due to a constantly on ion engine with a supply of xenon. Since then, the agency has been developing a ramjet ion thruster for similar low-orbit satellites, and has now conducted the first tests of such a thruster.
The tests took place in a vacuum chamber in which the engine was located. Initially, accelerated xenon was fed into it. After that, a mixture of oxygen and nitrogen was added to the gas intake device, simulating the atmosphere at an altitude of 200 kilometers. At the end of the tests, the engineers conducted tests with exclusively air mixture to check the performance in the main mode.
Engine tests with air as fuel
Direct-flow ion engine
