Inductively coupled plasma

An inductively coupled plasma (ICP) is a type of plasma source in which the energy is supplied by electrical currents which are produced by electromagnetic induction, that is, by time-varying magnetic fields. [A. Montaser and D. W. Golightly, eds. Inductively Coupled Plasmas in Analytical Atomic Spectrometry, VCH Publishers, Inc., New York, 1992.]

Operation

There are two types of ICP geometries: planar and cylindrical. In planar geometry, the electrode is a coil of flat metal wound like a spiral. In cylindrical geometry, it is like a helical spring.

When a time-varying electric current is passed through the coil, it creates a time varying magnetic field around it, which in turn induces azimuthal electric currents in the rarefied gas, leading to break down and formation of a plasma. Argon is one example of a commonly used rarefied gas.

Plasma temperatures can range between 6 000 K and 10 000 K, comparable to the surface of the sun.

ICP discharges are of relatively high electron density, on the order of 10¹⁵ cm^-3.

As a result, ICP discharges have wide applications where a high density plasma is necessary. Another benefit of ICP discharges is that they are relatively free of contamination because the electrodes are completely outside the reaction chamber. In a capacitively coupled plasma (CCP), in contrast, the electrodes are often placed inside the reactor and are thus exposed to the plasma and subsequent reactive chemical species.

Applications

* ICP-AES, a type of atomic emission spectrometry
* ICP-MS, a type of mass spectrometry.
* ICP-RIE, a type of reactive ion etching.

ee also

*Pulsed inductive thruster

References

External links

* [http://www.cee.vt.edu/ewr/environmental/teach/smprimer/icp/icp.html Inductively Coupled Plasma by Traci Bradford and M. Nicole Cook]
* [http://www.jobinyvon.com/Emission/Principle Principle of Atomic Emission]