S.1 Spacecraft Propulsion Systems Chapter 1: Introduction to ...
S.1 Spacecraft Propulsion Systems Chapter 1: Introduction to ...
S.1 Spacecraft Propulsion Systems Chapter 1: Introduction to ...
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Electrostatic <strong>Systems</strong><br />
- 59-<br />
Electrostatic <strong>Systems</strong>, where usually a high molecular propellant, such as Xenon gas, is<br />
ionized (ion thruster) by e.g. electron bombardment (Kaufman), in a high frequency<br />
electromagnetic field (radio-frequency) or by extracting ions from the surface of a liquid<br />
metal (cesium) under the effect of a strong electrostatic field (field emission).<br />
The ions are then accelerated <strong>to</strong> high velocity (30 <strong>to</strong> 60 km/s) by a strong electric field.<br />
Electrons are injected in<strong>to</strong> the ion beam from an electron emitter in order <strong>to</strong> keep it<br />
electrically neutral, thus preventing an electric charge build-up of the spacecraft.<br />
In addition <strong>to</strong> the above described category of ion thrusters, the Stationary Plasma<br />
Thruster (SPT) which belongs <strong>to</strong> the category of ‘Hall-effect Thrusters’, uses an applied<br />
magnetic field <strong>to</strong> control electrons in a quasi-neutral plasma discharge.