Magnetic field oscillating amplified thruster
Encyclopedia
The Magnetic Field Oscillating Amplified Thruster (MOA) (often named as Plasma Engine by the media) is a versatile electrothermodynamic system, which is able to accelerate nearly every medium to extremely high velocities, thereby generating a high energetic plasma jet in the exhaust.
To do so, MOA utilises a so-called Alfvén wave
, a physical principle within Magnetohydrodynamics
that was described first in 1942 by the later Nobelprize winner Hannes Alfvén
and which states that fluctuating magnetic fields can induce density waves in electric conductive media (e.g. Plasma
, salty water, etc.). These density waves can reach very high velocities and as the particles inside the medium are coupled to them, the particles are as well accelerated to very high velocities, accordingly reaching very high kinetic energies.
and/or the high particle energy, two prime application areas emerge: spaceflight
and coating
of particular materials.
For the spaceflight case, the high specific impulse leads to 90% reduction in propellant consumption when comparing MOA to current state-of-the-art ion engines.
For the coating case, the high kinetic energy of the exhaust particles leads to a high penetration depth within the target material. This allows for example to harden steel, aluminium and other metals, but also to change the material properties of glass and plastics.
An additional advantage of the MOA concept is its corrosion free behaviour, leading to a long lifetime of the system. The same magnetic fields that generate the Alfvén waves, prohibit high energy particles from hitting the thruster's wall or any other of MOA's structural components, therefore avoiding any particle induced damage almost inherently.
In principle the MOA thruster is composed of five subsystems:
The Plasma Generator produces a continuous flow of ionized particles, which drift inside the Central Tube towards the exhaust nozzle. These particles could for example be Nitrogen
- or Hydrogen
molecules, as well as nobles gases like Argon
or Xenon
. Since the particles are ionized, they react on the two magnetic fields, which are generated by the Primary and the Secondary Coil. Of these two, the Primary Coil is permanently switched on as it also forms the magnetic exhaust nozzle, while the Secondary Coil is cyclically switched on and off to deform the magnetic field lines of the system. By this deformation Alfén Waves are generated, which – in the next step – transport, compress and accelerate the propulsive medium to specific pre-defined parameters. Finally the Supply and Control Units make sure that the MOA thruster operates within the anticipated parameters.
As the concept requires a plasma generator to produce the ionized particles, MOA can in principle be described as an electric propulsion system, similar to an ion engine. However, because of the interaction of the magnetic fields, the particles are as well compressed and adiabatically heated up, thereby turning the whole system into a electrothermodynamic system. The combination of electric and thermodynamic principles leads also to a unification of the respective advantages. As such MOA features on one hand the high efficiency of the electric propulsion systems and on the other hand the ability to accelerate a high number of particles – just like a thermal system – therefore achieving a relatively high thrust at a high specific impulse.
The combination of high particle energy/exhaust velocity and relatively high thrust in this form is absolutely extraordinary. The high flexibility of changing thrust and specific impulse in-flight by adapting massflow and power consumption is at the moment a complete unique feature only provided by this novel thruster concept.
in Fukuoka
, Japan, on October 21, 2005. In a next step, a dedicated company called Qasar Technologies GmbH had been set up to further develop the MOA technology and to test potential terrestrial applications, both for spaceflight, in the area of coating and other areas. In summer 2005, the MOA prototype has reached TRL 5 (technology readiness level
) after the component and/or breadboard has been validated in a relevant environment – the vacuum chamber at the Graz Technical University.
The scientists foresee several potential customers for the MOA technology, such as aerospace companies like EADS
, Hughes Network Systems or Alcatel
Alenia Space, aircraft manufacturers like Boeing
, as well as companies specializing in materials and within automotive sector.
To do so, MOA utilises a so-called Alfvén wave
Alfvén wave
An Alfvén wave, named after Hannes Alfvén, is a type of magnetohydrodynamic wave.-Definition:An Alfvén wave in a plasma is a low-frequency travelling oscillation of the ions and the magnetic field...
, a physical principle within Magnetohydrodynamics
Magnetohydrodynamics
Magnetohydrodynamics is an academic discipline which studies the dynamics of electrically conducting fluids. Examples of such fluids include plasmas, liquid metals, and salt water or electrolytes...
that was described first in 1942 by the later Nobelprize winner Hannes Alfvén
Hannes Alfvén
Hannes Olof Gösta Alfvén was a Swedish electrical engineer, plasma physicist and winner of the 1970 Nobel Prize in Physics for his work on magnetohydrodynamics . He described the class of MHD waves now known as Alfvén waves...
and which states that fluctuating magnetic fields can induce density waves in electric conductive media (e.g. Plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...
, salty water, etc.). These density waves can reach very high velocities and as the particles inside the medium are coupled to them, the particles are as well accelerated to very high velocities, accordingly reaching very high kinetic energies.
Application areas
Because of the high exhaust velocities and the associated high specific impulseSpecific impulse
Specific impulse is a way to describe the efficiency of rocket and jet engines. It represents the derivative of the impulse with respect to amount of propellant used, i.e., the thrust divided by the amount of propellant used per unit time. If the "amount" of propellant is given in terms of mass ,...
and/or the high particle energy, two prime application areas emerge: spaceflight
Spaceflight
Spaceflight is the act of travelling into or through outer space. Spaceflight can occur with spacecraft which may, or may not, have humans on board. Examples of human spaceflight include the Russian Soyuz program, the U.S. Space shuttle program, as well as the ongoing International Space Station...
and coating
Coating
Coating is a covering that is applied to the surface of an object, usually referred to as the substrate. In many cases coatings are applied to improve surface properties of the substrate, such as appearance, adhesion, wetability, corrosion resistance, wear resistance, and scratch resistance...
of particular materials.
For the spaceflight case, the high specific impulse leads to 90% reduction in propellant consumption when comparing MOA to current state-of-the-art ion engines.
For the coating case, the high kinetic energy of the exhaust particles leads to a high penetration depth within the target material. This allows for example to harden steel, aluminium and other metals, but also to change the material properties of glass and plastics.
An additional advantage of the MOA concept is its corrosion free behaviour, leading to a long lifetime of the system. The same magnetic fields that generate the Alfvén waves, prohibit high energy particles from hitting the thruster's wall or any other of MOA's structural components, therefore avoiding any particle induced damage almost inherently.
Set-up of the MOA System
- Plasma Generator,
- Central Tube,
- Primary Coil,
- Secondary Coil,
- Supply and Control Units.
The Plasma Generator produces a continuous flow of ionized particles, which drift inside the Central Tube towards the exhaust nozzle. These particles could for example be Nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
- or Hydrogen
Hydrogen
Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...
molecules, as well as nobles gases like Argon
Argon
Argon is a chemical element represented by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide...
or Xenon
Xenon
Xenon is a chemical element with the symbol Xe and atomic number 54. The element name is pronounced or . A colorless, heavy, odorless noble gas, xenon occurs in the Earth's atmosphere in trace amounts...
. Since the particles are ionized, they react on the two magnetic fields, which are generated by the Primary and the Secondary Coil. Of these two, the Primary Coil is permanently switched on as it also forms the magnetic exhaust nozzle, while the Secondary Coil is cyclically switched on and off to deform the magnetic field lines of the system. By this deformation Alfén Waves are generated, which – in the next step – transport, compress and accelerate the propulsive medium to specific pre-defined parameters. Finally the Supply and Control Units make sure that the MOA thruster operates within the anticipated parameters.
As the concept requires a plasma generator to produce the ionized particles, MOA can in principle be described as an electric propulsion system, similar to an ion engine. However, because of the interaction of the magnetic fields, the particles are as well compressed and adiabatically heated up, thereby turning the whole system into a electrothermodynamic system. The combination of electric and thermodynamic principles leads also to a unification of the respective advantages. As such MOA features on one hand the high efficiency of the electric propulsion systems and on the other hand the ability to accelerate a high number of particles – just like a thermal system – therefore achieving a relatively high thrust at a high specific impulse.
The combination of high particle energy/exhaust velocity and relatively high thrust in this form is absolutely extraordinary. The high flexibility of changing thrust and specific impulse in-flight by adapting massflow and power consumption is at the moment a complete unique feature only provided by this novel thruster concept.
Current status
After a propulsion concept based on Alfvén waves was first proposed in the middle of the 1980s, the MOA concept was first tested at Graz Technical University in the vacuum chamber of the Institute of Communication Networks and Satellite Communication. The test campaign lasted several weeks and showed the feasibility of the MOA concept. The obtained results were presented at the International Astronautical CongressInternational Astronautical Congress
Every year, the International Astronautical Federation together with the International Academy of Astronautics and the International Institute of Space Law , holds the International Astronautical Congress which is hosted by one of the national society members of the IAF.They are an annual meeting...
in Fukuoka
Fukuoka, Fukuoka
is the capital city of Fukuoka Prefecture and is situated on the northern shore of the island of Kyushu in Japan.Voted number 14 in a 2010 poll of the World's Most Livable Cities, Fukuoka is praised for its green spaces in a metropolitan setting. It is the most populous city in Kyushu, followed by...
, Japan, on October 21, 2005. In a next step, a dedicated company called Qasar Technologies GmbH had been set up to further develop the MOA technology and to test potential terrestrial applications, both for spaceflight, in the area of coating and other areas. In summer 2005, the MOA prototype has reached TRL 5 (technology readiness level
Technology Readiness Level
Technology Readiness Level is a measure used by some United States government agencies and many of the world's major companies to assess the maturity of evolving technologies prior to incorporating that technology into a system or subsystem...
) after the component and/or breadboard has been validated in a relevant environment – the vacuum chamber at the Graz Technical University.
The scientists foresee several potential customers for the MOA technology, such as aerospace companies like EADS
EADS
The European Aeronautic Defence and Space Company N.V. is a global pan-European aerospace and defence corporation and a leading defence and military contractor worldwide...
, Hughes Network Systems or Alcatel
Alcatel
Alcatel Mobile Phones is a brand of mobile handsets. It was established in 2004 as a joint venture between Alcatel-Lucent of France and TCL Communication of China....
Alenia Space, aircraft manufacturers like Boeing
Boeing
The Boeing Company is an American multinational aerospace and defense corporation, founded in 1916 by William E. Boeing in Seattle, Washington. Boeing has expanded over the years, merging with McDonnell Douglas in 1997. Boeing Corporate headquarters has been in Chicago, Illinois since 2001...
, as well as companies specializing in materials and within automotive sector.