You may have only seen ion drives on sci-fi movies and read it on books about space travel, but NASA has been working on it since the 1950s.
NASA recently completed the test for the longest duration a space propulsion system can last. NASA’s Evolutionary Xenon Thruster (NEXT) prototype accomplished a record-breaking 48,000 hours (that’s more than 5 years) of operation and acceleration and that was already years ago. Imagine how further we can get with today’s technology.
Ion propulsion doesn’t generate much thrust so it can’t be used to launch a spacecraft into space. The force it expels is just equivalent to a paper pushing your hand downwards due to gravity. You won’t feel any force from it, but if you take that tiny amount of power in space where there’s no gravity and frictional resistance is negligible, you’ll achieve astounding results.
The speed the ion drive generates may be very minute but its value shows as it compounds velocity over time. It can push a spacecraft up to 320,000 km/h, although it takes a huge amount of time to achieve that. Experts say that ion propulsion is 10 times more efficient compared to traditional thrusters using chemicals as fuel, making it more suitable for deep-space travels.
Ions are produced from charged atoms or molecules. A particle either loses or gains charge by shedding or combining with electrons to form charged particles. These ions, by nature, move according to the surrounding magnetic field’s orientation and this is where the ion propulsion capitalizes on.
Ion propulsion works by ionizing particles to generate thrust. NASA uses xenon due to its stability and low explosion risk.
The propulsion system works like this: Inside the discharge chamber, magnetic rings are aligned to generate a magnetic field. Neutral particles of xenon are released out of the propellant injector and into the discharge chamber. At the same time, negatively charged particles are also introduced into the chamber through the discharge cathode.
The bombarded electrons from the discharge cathode will eventually find the neutral atom, colliding with it and ionizing it in the process. The positive ions ejected due to the ionization process accelerate through the gridded ion thruster, which is located at the lowest part of the system, and are eventually expelled out of the spacecraft.
The collection of ejected positive ions – called ion beam – are again combined with the electrons released from the neutralizer to make the particle neutrally charged. This is necessary to prevent the positive ions from creating a drag force that reduces the efficiency of the thrusters and hampers the propulsion speed of the spacecraft.
This whole process is repeated, producing the needed thrust to propel the spacecraft forward.
Continuous developments are in place and ion thrusters are expected to fuel a wide range of space missions including defense and possibly commercial applications in the near future.