Ion thrust engine
Gases can be ionized to propel an engine in a process known as ion propulsion. In order to produce thrust, gases such as Argon and Xenon are propelled electrically and attain very high velocities. The engines are capable of producing small thrust at specific impulses a factor which is critical in applications involving space (Harrison, 2006). The ion-propulsion system comprises five essential parts including: the control computer, the management system of the propellant, the ion thruster, the processing unit for power and the power source. The power generated by the power source is converted into the power required by each component by the power processing unit. This is due to the varying power and current loads required for each constituent component (Harrison, 2006).
The X3 thruster is a variant of the Hall thruster. This design makes the use of a stream of ions to facilitate the propulsion of a spacecraft. In order to generate thrust, the thruster expels plasma. The result is that greater speeds will be achieved than those attainable by a regular chemical propulsion rocket. The maximum velocity that a chemical propelled rocket can attain is about five kilometres per second compared to a Hall thruster which can reach speeds of up to 40 kilometres per second. The gains in speed are very important to travelling in space over long distances such as taking humans to Mars (Jones & Bergan, 2017). In the most recent test performed, the X3 thruster broke records creating hope that the technology can be employed in moving humans to Mars. Among the records broken was the production of 5.4 N of force an excess of 2.1 N over the last record. Moreover, the engine increased the operating current record more than twice from 112 A to 250 A (Nowakowski, 2018). Indeed the leaders running the project estimate that the technology, which runs on ion propulsion, would be ready, within the next 20 years, to ferry human beings to Mars.
In order to transport a similar amount of cargo and crew over the same long distance, chemical-propelled engines require significantly more propellant than ion-propelled engines. This makes them more efficient in terms of consumption. As noted by Jones & Bergan, (2017), the ion propelled engine can attain speeds ten times faster using the same fuel as a chemical-powered engine. The engine is also considered to be much safer.
According to Jones & Bergan, (2017), results from tests performed reently show that the X3 thruster can attain over 100kW of power all whilst ushing with a thrust of 5.4 N. This is the highest ever attained by an ion thruster. While this is a great feat, the thruster has several inherent limitations. For example, the thrust required to propel a body to Mars efficiently lies between 200 to 400 kW whereas the thruster produces 100 kW (Nowakowski, 2018). It would therefore require a much longer period of time to attain the same acceleration as a chemical-powered system. This makes the thruster unsuitable for the launch process. With a weight of about 507 lbs and a diameter of 0.8m. the engine is very bulky (Nowakowski, 2018).
In order to solve these challenges, engineers are proposing the use of multiple conduits of plasma into the thruster. However, this runs the risk of making the engine verry bulky and less compact. In order to facilitate movement of the engine, unlike other hall engines, the X3 has to be picked up by a crane (Jones & Bergan, 2017).
Harrison, F. (2006). Apparatus for Study of Ion-Thruster Propellant Ionization. Monterey: Naval Postgraduate School.
Jones, B., & Bergan, B. (2017, October 13). NASA’s New Ion Thruster Breaks Records, Could Take Humans to Mars. Retrieved from Futurism: https://futurism.com/nasas-new-ion-thruster-breaks-records-could-take-humans-to-mars/
Nowakowski, T. (2018, February 19). Could the X3 Ion Thruster Propel Us To Mars? Retrieved from Spaceflight Insider: http://www.spaceflightinsider.com/organizations/nasa/x3-ion-thruster-propel-us-mars/