How our technology works

Ion thrusters

Our thrusters are of conventional Kaufman configuration, with a direct current (DC) discharge between a hollow cathode and a cylindrical anode used to ionise the propellant gas. The efficiency of this plasma production process is enhanced by the application of a magnetic field within the discharge chamber. A grid system, forming the exit to the discharge chamber, extracts and accelerates the ions, to provide the required thrust.

The velocity of the ejected ions depends only on the beam potential, whereas the thrust is a function of this and the ion beam current. An external hollow cathode, referred to as the neutraliser, emits the electrons necessary to neutralise the space charge of the emerging ion beam.

Cathodes

Our cathodes are concentric cylindrical assemblies in a heater element which is used to raise the temperature of the emitter until thermionic emission occurs. This is normally in the region of 750 to 1000^oC. Propellant gas is then passed through the tube and a voltage is applied to an external electrode, often referred to as the keeper or ignitor. A discharge spontaneously occurs and transfers automatically into the cathode cavity.

Once discharge initiation has occurred the heater power can be turned off because ion bombardment of the tip and dispenser provides the necessary input of energy to maintain the temperature required for emission.