What is an ion?
An ion is an atom that has a positive or negative charge. When an atom or molecule has an equal number of protons and electrons, it is balanced or neutral. If an electron is lost the atom becomes positively charged. If an electron is gained, it becomes negatively charged.
Air is a mixture of gases including nitrogen, oxygen, carbon dioxide, water vapor and other trace gases, any one or more of which can be ionized. When any one or more of these gas molecules gains or loses an electron is becomes charged and thus called air ions.
According to Wikipedia an air ionizer is a device that uses high voltage to ionize or electrically charge air molecules. Air ionizers are used in many different applications from purifying the air of particulates, contaminants and allergens to controlling electrostatic discharge (ESD) in work environments.
How do air ionizers create ions?
There are two methods air ionizers work. The first is alpha ionization, which uses a nuclear source such as polonium 210. The polonium 210 particles collide with the air, transferring electrons, causing the neutral air molecules to become negative ions. Since the polonium loses electrons, it becomes a positive ion. Alpha ionizers are beneficial because they create an equal number of positive and negative ions.
The second method is called corona ionization, which uses an electrical current to create bipolar ionized air. The ionizer applies a high-voltage electrical current composed of a flow of negatively charged electrons, to a metal prong or needle. Electrostatic repulsion causes the electrons to detach from the prong or needle, attaching themselves to the molecules or nitrogen and oxygen in the air, forming negative ions, which are attracted to the static charge in the work environment thus neutralizing it. These ions also attract certain types of molecules in the work environment like dust and other air particulates. These particulates cluster around the ion, weighing it down and forcing it to fall to the ground, cleaning the air.
Corona ionization can further be divided into AC and DC. AC or alternating current ionization uses one emitter to produce both positive and negative ions. This type of ionization is mainly used to protect components during assembly. DC or direct current uses separate positive and negative power supplies that run simultaneously to create bipolar ions. DC ionizers are more efficient at producing ions and use lower operating currents, making them a better fit for cleanroom applications.
Air ionizers are the best option for any environment working with materials like quartz, glass, plastic, and ceramic are inherently charge generating because these materials are insulators, this charge cannot be easily removed by grounding. However, air ionization should only be one part of controlling ESD in work environments.
Production Automation offers a wide variety of air ionizers from Simco including room systems, benchtop and overhead blowers, point-of-use blowers, air guns, nozzles and specialty ionizers for nitrogen, CDA, hi-temperature, and tight confines applications.