Atmospheric pressure plasmas are primarily generated using various excitation methods, allowing for their application in diverse industrial processes. The most industrially significant sources include DC, AC, and microwave excitation techniques.
Here's a breakdown of the common sources:
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DC Excitation (Electric Arc):
- DC excitation typically generates thermal plasmas, often referred to as electric arcs.
- These arcs are characterized by high temperatures and are commonly used in applications like welding and material processing.
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AC Excitation:
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AC excitation is versatile and can produce both thermal and non-thermal plasmas.
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Several techniques fall under this category:
- Corona Discharge: Uses sharp electrodes to create localized plasma, often used in surface treatment.
- Dielectric Barrier Discharge (DBD): Employs a dielectric material to prevent arcing, creating a more uniform plasma. DBDs are widely used for surface modification, sterilization, and ozone generation.
- Piezoelectric Direct Discharge: Utilizes piezoelectric materials to generate high voltages and create plasma. These are known for their compactness and lower power consumption.
- Plasma Jets: Project plasma into the surrounding atmosphere, enabling localized treatment. They use various gases and are frequently employed in biomedical applications and surface cleaning.
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Microwave Excitation (2.45 GHz Microwave Microplasma):
- Microwave excitation, particularly at 2.45 GHz, is used to create microplasmas.
- These microplasmas are beneficial for applications requiring precise and localized plasma treatment.
In summary, the main sources for generating atmospheric pressure plasmas are DC excitation (electric arc), AC excitation (corona discharge, dielectric barrier discharge, piezoelectric direct discharge, and plasma jets), and 2.45 GHz microwave microplasma. The specific method used depends on the desired plasma characteristics and the intended application.
