What Is an Ion Counter?
An ion counter is a device that is supposed to measure air ions, which are charged particles suspended in the air, especially negatively charged small ions.
With the negative ion boom in the 2000s, various types of ion counters are now available to measure the amount of negative ions in the environment.
For highly accurate measurement, it is desirable to measure both negative and positive ions at the same time, but there are also types that display only negative ions. This type is often used for sales promotions of home appliances, etc., where only negative ion values are to be displayed.
Uses of Ion Counters
Ion counters are used for research and industrial purposes at universities and companies. They are also used as sales promotion equipment to indicate the amount of negative ions generated by home appliances.
Since negative ions have become a popular topic of conversation about their health benefits, they have become more and more visible to the public as a machine that detects negative ions.
Principle of Ion Counters
The Ebert measuring device is the basic principle for measuring air ions, and the Gerdien method, an application of the Ebert measuring device, is the current mainstream method. In the Gerdien method, a voltage is applied to the outer cylinder of a double-cylinder device, and when a fan is used to inject a constant flow of air into the cylinder, positive ions are measured when the voltage is positive, and negative ions are measured when the voltage is negative.
Since each ion in the air has a different mobility, the mobility of the ions that can be supplemented by the ion counter is called the critical mobility. Ions with mobility greater than the critical mobility are captured by the Ion Counter, while ions with mobility less than the critical mobility are not captured.
If the voltage is increased, a point appears at which the current becomes constant, and if there were only small ions, all small ions would be captured by the ion counter. The following equation expresses the concentration of small ions at this time.
Concentration of small ions = saturation current/eΦ (e = elementary amount of charge, Φ = flow rate of air through the cylinder per unit time)
What is important here is the mobility of the ions. This is because some people believe that small ions are better for the body. When measuring ions, it is important to know the mobility of the ions being measured by the ion counter. It should be noted, however, that the question of which ions are beneficial to health is still under debate, and not all small ions are beneficial.
Types of Ion Counters
The current mainstream of ion counters is the double-cylinder type described as the principle, but there are several other types.
1. Parallel Plate Type
The parallel plate type is inexpensive and suitable for simple measurements. Although it is not expected to be highly accurate, it is used to determine the approximate amount of ions and for pre-shipment inspections of ion generators.
2. Ore-Specific Type
Ion counters are used for measuring the ions in natural ores that emit radiation. They measure the ions of natural ores, such as radium and monazite.
3. Ion Detection Type
The ion detection type is a simpler device than the parallel plate type. Also called an ion checker, this device is used to determine whether ions are generated.
Other Information on Ion Counters
Definition of Negative Ions
The idea that negative ions are good for your health at this time should be viewed as a scientifically untenable view. First of all, the term “negative ion” is not a technical term, although it is widely used in the world.
One way to understand negative ions can be found in the “Science of Pseudoscience” research report collection published by Osaka University in 2019. It concludes, “As long as negative ions cannot be clearly defined, we cannot discuss their effects in general. We should not easily jump to information on TV and other media.”
In addition, “We are required to acquire the ability to question, or in other words, media literacy, rather than just believing information on TV, magazines, and the Internet. Particularly today, with so much information around us, we need to be even more careful.”