Inductively Coupled Plasma - Inductively coupled plasma
An inductively coupled plasma can be generated by directing the energy of a radio frequency generator into a suitable gas, usually ICP argon. Other plasma gases used are Helium and Nitrogen. It is important that the plasma gas is pure since contaminants in the gas might quench the torch.
Coupling is achieved by generating a magnetic field by passing a high frequency electric current through a cooled induction coil. This inductor generates a rapidly oscillating magnetic field oriented in the vertical plane of the coil. Ionization of the flowing argon is initiated by a spark from a Tesla coil. The resulting ions and their associated electrons from the Tesla coil then interact with the fluctuating magnetic field. This generates enough energy to ionize more argon atoms by collision excitation. The electrons generated in the magnetic field are accelerated perpendicularly to the torch. At high speeds, cations and electrons, known as eddy current, will collide with argon atoms to produce further ionization which causes a significant temperature raise. Within 2 ms, a steady state is created with a high electron density. A plasma is created in the top of the torch. The temperature within the plasma ranges from 6,000-10,000 K. A long, well-defined tail emerges from the top of the high temperature plasma on the top of the torch. This torch is the spectroscopic source. It contains all the analyte atoms and ions that have been excited by the heat of the plasma.
The success of ICP leans on its capability to analyze a large amount of samples in a short period with very good detection limits for most elements.
ICPs used in the market today are often connected to different detection systems, such as ICP mass spectrometry and ICP atomic emission spectrometry.