The NASA spacecraft which spent more than 7 years travelling across the Solar System. And it Is intercepting the asteroid Vesta and the planet Ceres. Now it is orbiting around Ceres. The probe has returned the first images from these distant objects. The spacecraft is the first exploratory space mission to use an electrically powered ion engine rather than conventional rockets.
The ion engine will propel the next generation of spacecraft. Electric power is used to make charging of the particles of the fuel. Usually the gas xenon, accelerate them to very high velocities. The exhaust velocity of the rockets is limited by the chemical energy. Which is stored in the fuel’s molecular bonds. And it limits the thrust to about 5 [km/s]. Ion engines are in principle limited only by the available electrical power on the spacecraft. But typically it is the exhaust speed of the charged particles which range is 15 [km/s] to 35 [km/s].
Electric space power for ion engine for spacecraft
There are three broad types of electric propulsion. And t depends on the method which is used to accelerate the fuel. Electrothermal engines use only electric power. Which is heating the propellant. By currently passing through a heating element. The configuration known as a resistojets. Or by arcjet, passing a current through the hot ionized gas or plasma. Electromagnetic engines, ionise the propellant by turning it into an electrically conductive plasma. Which is accelerated via the interaction of a high electrical current and a magnetic field. Known as pulsed plasma thrusters. This technique is in fact quite similar to how an electric motor works.
Electrostatic engines use an electric field generated by applying a high voltage to two grids. They are perforated with many tiny holes to accelerate the propellant. That is called a gridded ion engine. Another electrostatic design is the Hall effect thruster. Which operates in a similar fashion. But instead of high voltage grids generates an electric field at the thruster’s exit plane. By trapping electrons in a magnetic field.