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FAQs | VUV Ionizer: Electrostatic charge removers
VUV Ionizers are electrostatic charge removers that use "photoionization" to apply vacuum UV light to remove static electricity. This innovative ionization method makes use of unique features of vacuum UV light to eliminate unwanted electrostatic charges in a vacuum (depressurized state) which has been impossible up to now.
- Do VUV Ionizers emit vacuum UV light immediately after power-on?
- Does vacuum UV light have any effects on target objects?
- What are the residual atoms and molecules that contribute to photoionization by vacuum UV light?
- In which area can electrostatic charges be most efficiently removed?
- How do the characteristics change depending on the irradiation distance?
- What is the reason for the difference between positive charging and negative charging in electrostatic charge removal effect?
- Is it possible to obtain a electrostatic charge removal effect in an atmospheric environment?
- Does the electrostatic charge removal effect differ depending on the degree of vacuum?
- When using VUV Ionizers in a gaseous environment, is there any gas that might cause adverse effects?
- Can I perform ON / OFF irradiation control at short time intervals?
- How should I maintain the light source unit?
- How do I decide when to replace the light source unit?
- Is baking of a vacuum chamber possible while a VUV Ionizer is still installed to it?
- Can you customize VUV Ionizers?
- Is pre-evaluation possible?
- Are there any laws and regulations that need to be followed when installing and using VUV Ionizers?
Do VUV Ionizers emit vacuum UV light immediately after power-on?
No, this is because the deuterium lamp incorporated in VUV Ionizers uses a thermal cathode that requires a warm-up time (filament preheating time) of about 20 seconds after power-on. Vacuum UV light is not emitted during this warm-up time.
Does vacuum UV light have any effects on target objects?
Vacuum UV light energy is high and might damage target objects exposed to vacuum UV light for extended periods of time.
The extent of damage depends on the type of object so we recommend confirming that the target objects are not damaged under the same irradiation conditions as during actual usage. If you send us a target object sample we will confirm effects from vacuum UV irradiation on the target object. Please feel free to consult us about this.
If you do not want to directly irradiate the target objects with vacuum UV light, we suggest indirect irradiation to remove electrostatic charges. In this case, however, the electrostatic charge removal effect will be lower than when using direct irradiation so please consult us about this.
What are the residual atoms and molecules that contribute to photoionization by vacuum UV light?
The residual atoms and molecules in the vacuum chamber originate from atmospheric components or namely components in the air.
In which area can electrostatic charges be most efficiently removed?
Electrons and ions are generated by irradiation of vacuum UV light, so electrostatic charges will be most efficiently removed in the entire area irradiated by vacuum UV light. If an even higher electrostatic charge removal effect is needed, we recommend irradiating vacuum UV light directly onto the target object.
How do the characteristics change depending on the irradiation distance?
Vacuum UV light from the deuterium lamp contained in VUV Ionizers spreads with a light distribution angle starting from the light emission point. This means the longer the irradiation distance, the wider the irradiated area. However, as the distance to the target object increases, the light output attenuates or weakens, which causes the amount of generated ions to decrease and degrade the electrostatic charge removal effect.
What is the reason for the difference between positive charging and negative charging in electrostatic charge removal effect?
Electrons and negative ions work to neutralize positive charges, while positive ions help to neutralize negative charges. This process and the moving speed of the ions and electrons likely cause different electrostatic charge removal effects.
Is it possible to obtain a electrostatic charge removal effect in an atmospheric environment?
No, a electrostatic charge removal cannot be obtained in an atmospheric environment or namely in the air.
Since vacuum UV light emitted from VUV Ionizers is absorbed by oxygen, a electrostatic charge removal effect can only be obtained in a vacuum or in an environment where oxygen was sufficiently replaced with an inert gas such as nitrogen.
If electrostatic charge removal is required in an atmospheric environment, then please use our PhotoIonizers.
Does the electrostatic charge removal effect differ depending on the degree of vacuum?
As the degree of vacuum increases, the number of the residual atoms and molecules decreases and the electrostatic charge removal effect also weakens slightly. However, we have verified that there is no significant decrease in the electrostatic charge removal effect until the vacuum level reaches about 10-6 Pa.
When using VUV Ionizers in a gaseous environment, is there any gas that might cause adverse effects?
The window material of the deuterium lamp in VUV Ionizers uses an MgF2 crystal that is not adversely affected by the following gases.
• Rare gases
• Gases originating from atmospheric air
• Halogen-based gases (HCL, HF)
• Freon-based gases (CF4, CCl2F2, etc.)
Please consult us when using VUV Ionizers in other environments.
Can I perform ON / OFF irradiation control at short time intervals?
Intermittent lighting ranging from a few seconds to several minutes will shorten the lamp operating life. To perform ON / OFF irradiation control at time intervals within a few seconds to several minutes, we recommend using a shutter to interrupt the vacuum UV light.
In the case of the L12542, the guaranteed life is 2000 hours and the expected operating life during continuous lighting is 6000 hours or more. However, when operated intermittently at time intervals from a few seconds to several minutes, the actual operating life may be shorter than the guaranteed life in some cases.
How should I maintain the light source unit?
When cleaning the window for the deuterium lamp in the VUV Ionizer, wipe the window surface with a soft cloth moistened with a volatile solvent such as acetone and then wipe it with dry cloth so that no volatile solvent remains on the window surface. If dirt or contaminants adhere to the window surface, these may cause burn-in (partial opacity) when the lamp is lit up, leading to poor electrostatic charge removal (light output attenuates or weakens due to premature loss of window transmittance).
How do I decide when to replace the light source unit?
We recommend replacing the light source unit before the guaranteed life has expired or after a certain specified operating time has elapsed. The operating time can be calculated from the lamp status signal of the external control terminal on the power supply unit.
Basically, the electrostatic charge removal effect continues as long as the lamp still lights up. Please consult us if concerned about the correct lamp replacement period.
Is baking of a vacuum chamber possible while a VUV Ionizer is still installed to it?
In the case of the L12542 and L15094 which are designed to be installed outside a vacuum chamber, baking of the vacuum chamber is possible unless the temperature of the vacuum chamber surface (vacuum flange mount) exceeds 140 ℃. But do not emit vacuum UV light (do not turn on the light source) during baking.
Please consult us if the temperature of the vacuum chamber surface will be higher than 140 ℃ or you want to emit vacuum UV light during baking.
When using the L10706 whose main unit is designed to be installed inside a vacuum chamber, do not bake the vacuum chamber at a temperature higher than the storage temperature specified for the L10706.
Can you customize VUV Ionizers?
Yes, we will customize VUV Ionizers and vacuum flanges to match your applications and usage conditions so please feel free to consult us about this.
Besides designing and manufacturing vacuum flanges, we also provide technical support for design issues.
Is pre-evaluation possible?
We do simulations and also have demo units available for leasing. Please feel free to contact us about this.
Are there any laws and regulations that need to be followed when installing and using VUV Ionizers?
There are no specific laws or regulations that need to be followed at this time.
However, if you are concerned about the effects of ultraviolet light on the human body, please take necessary action after referring to the following points.
• Be sure to wear protective equipment when handling a VUV Ionizer.
• Shield the viewing port by sticking a color film or similar item on it.
Operating a VUV Ionizer in the air even just temporarily will generate ozone, so be sure to ventilate the room.
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