Ion pump
An ion pump works by creating an electric field across a fluid containing ions. An ion is an electrically charged atom or molecule. If the fluid does not naturally contain ions, then it must be ionized before an ion pump will work. A fluid is ionized either by addition of an ionic substance, or by electrostatic discharge (ESD) caused when the electric field strength exceeds the dielectric strength (approximately 30 kV/cm in air [1]). By exerting an electric voltage across two insulated or uninsulated electrode surfaces on either side of the fluid, an electric force is exerted on each charged particle within the fluid. The force magnitude on each particle is equal to the product of the electric field strength and the electric charge of the particle, (note that the direction of the force depends on the sign of the charge). The net pressure created by the pump will be the summation of the electric forces divided by the cross sectional area of the pump. If the fluid contains any non-charged particles, then these will be pushed along by the charged particles to the extent that the fluid is viscous.
References
Sources
- Hablanian, Marsbed. "Gettering and Ion Pumping". High-Vacuum Technology: A Practical Guide (ISBN 082478197X).
- "Sputter Ion Pumps" (PDF). Paul Scherrer Institute.