Recent developments in high-frequency research
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| Rok publikování | 2025 |
| Druh | Konferenční abstrakty |
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| Popis | Dielectric barrier discharges (DBD) are an important source of non-equilibrium low temperature plasma. Commonly used DBDs are powered by high voltage (HV) generators producing alternating current in frequencies from tens of Hz to hundreds of kHz. Although there exist power sources able to produce signals with higher frequencies, up to tens of MHz, the amplitude of the HV signal is limited to 1-2 kV. This amplitude is sufficient to power DBDs in noble gases only, e.g. in Ar.Thanks to recent advances in high-frequency power electronics and new ferrite materials, we designed and constructed novel HV resonant transformers and power inverters. First versions of HV transformer allowed us to produce 2-3 MHz HV signal with up to 4kV amplitude sufficient to ignite plasma in coplanar DBD in argon and mixture of argon and nitrogen, as well as volume DBD (e.g. in atomizers). This enabled us to reveal promising properties of MHz coplanar DBDs, e.g. significantly higher plasma height.Further development and optimization of MHz resonant transformers and inverters lead to significant improvement of maximal voltage to 20 kV and extend available frequencies to 1,5-4 MHz. Although this improvement by itself is sufficient to ignite plasma inambient air, electrode usually do not survive longer than 2 s due to rapid overheating. The solution to use MHz discharges in ambient air is to use the so-called dual-frequency mode, which combines low frequency (tens of kHz) and pulsed high frequency (MHz) discharge excitation. We summarize in this contribution recent achievements in MHz research reached in the last few years. The focus will be on MHz discharges for atomizers, dual-frequency discharges in air and CO2, developments in inverter and transformer optimization, and we will define challenges for future research in all these areas. |
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