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Comparing Ion Guns | AC vs DC Corona Ionization:


Air Ionizer Balance Decay Rate 1000v to 100v (per ESD S3.1) Output per Standard Cubic Foot (SCFM)

Ion

Output

Elimstat Sidekick 0 +/- 15 volts   < 2 seconds at 6" @ 30 PSI

2.4 @ 30 PSI 

4.6 @ 60 PSI 

7.4 @ 100 PSI 

Inherent Balance AC Corona Ionization
Elimstat Blow Off Gun 0 +/- 15 volts   < 2 seconds at 6" @ 30 PSI

2.4 @ 30 PSI 

4.6 @ 60 PSI 

7.4 @ 100 PSI 

Inherent Balance AC Corona Ionization
Simco-Ion™ AirForce Blow Off Gun 0 +/- 30 volts   1 second at 6" @ 30 PSI

41g @ 30 PSI
measured @ 3" from
a 2" diameter target

Steady State DC Corona Ionization

What is Ionization?

The ionization energy (IE) of an atom or molecule describes the minimum amount of energy required to remove an electron (to infinity) from the atom or molecule in the gaseous state.

What is Corona Ionization?

When AC (alternating current) and DC (direct current) high voltage is applied to a sharp emitter point it creates an electric field or "corona" around the emitter. This high voltage corona of ions then interacts with electrons in the nearby gas molecules creating either positive or negative ion clouds depending on whether positive or negative high voltage is used.

How does AC Corona Ionization Work?

When an AC power source is used the high voltage that is applied to a single emitter point cycles between negative and positive at line frequency (50/60 Hz). Since the cycles are so fast, there is a high level of recombination of ions. As the ionization depends on the power line directly, it is difficult to generate positive and negative ions in equal numbers. The AC ionizer consists of a single point (blowoff gun or nozzle), an array of such points arranged around a fan (AC Blower), a straight line of points (AC Bar), or an area (AC grid). Ionizers that employ AC corona must be accompanied by strong airflow to push ions away from emitter points. This can be inconvenient since the ionizer must rely solely on the environment it is installed into for its airflow, or else incorporate additional fans or blower devices. AC corona ionization is most appropriately used in industrial applications where the ionizer can be placed close to the charged objects and cleanliness is not required. AC corona ionizer designs are often simple and low cost, making them an attractive choice in many manufacturing environments.

How does DC Corona Ionization Work?

Unlike AC corona ionization, which emits both positive and negative ions from the same emitter point, DC corona ionizers emit ions from separate positive and negative emitter points. Since the ions are emitted from separate points, there is much less recombination of ions. Since ions are emitted independently for each polarity, it is possible to monitor and control the amount and the equality of ions emitting from the positive and negative emitter points. Various types of monitoring and control systems are available for DC corona ionizers. As a result, ionizers using DC corona offer great degrees of control and fine-tuning. The high level of system sophistication along with the low ion recombination rate also means that DC corona ionizers are appropriate for ESD-sensitive and contamination-critical technology applications.

Steady State DC. Steady State DC Corona Ionization continuously applies positive high voltage to half of the emitter points and negative high voltage to the other half. The ionizer may contain a single pair of emitters (blowoff guns or nozzles, and in ceiling emitters), an array of pairs of emitters (DC Blowers), or a straight line of emitter pairs (DC Bars). Steady-state DC ionization may be employed with low or high airflow, depending on how far apart the emitter points are spaced. Steady-state DC ionization is commonly used in room systems, laminar flow hoods, blowers, and blow-off guns.

Pulsed DC. Pulsed DC ionizers allow positive and negative emitter points to be turned on and off, creating clouds of positive and negative ions. Ionizers using pulsed DC may be finely tuned to allow timing cycles and polarities to operate as exactly needed for a specific application. Positive and negative emitters may be set to turn on alternately, usually in a time period of seconds. In certain areas, a greater proportion of one polarity may be needed over the other, or the time that the voltages are on may be stretched to prevent any recombination. Ionizers using pulsed DC can be appropriately used both in and out of the cleanroom, most commonly in ceiling emitters or bar-type ionizers. It is not efficient for use in ionizing blowers or blow-off guns.


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