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<專題討論>2020/11/26(四)14:10綜合大樓2樓48218教室演講 : 鄭雲謙 副教授(交通大學機械工程學系)

張貼者:2020年11月19日 下午7:06Dabby Lu
講題: Atmospheric-pressure Plasma Effects on Cancer Cells and Impedance Matching Circuit to Improve Plasma Power Conversion Efficiency
摘要: We compared the effects of plasma-activated medium (PAM) with thermal therapy on lung cancer with malignant pleural effusion (MPE). The conventional MPE managements, such as local chemotherapy, regional hyperthermia with CDDP, and photodynamic therapy, have side effects on the patients so that we need a new therapy to avoid harmful side effects on cancer patients. Recent studies show that plasma effectively induce apoptosis in cancer cells with minor effects on normal cells because of reactive oxygen/nitrogen species (RONS). Additionally, PAM by atmospheric-pressure plasma jets (APPJ) also has the similar effect. The PAM effects on MPE have not been investigated yet so far. Thus, we applied PAM to lung cancer cells (CL1-5) and benign cells from lung cancer patients to see its lethal effect. This study find out that the PAM can selectively kill lung cancer cells and the benign cells remain its viability. Besides, the thermal therapy kills both cancer cell and benign cells. It indicates that PAM would be likely to enhance the effect of lung-cancer treatment as adjuvant therapy in the future.

We also constructed an impedance matching circuit for a partial-discharge calibrated (PDC) atmospheric-pressure plane-to-plane DBD equivalent circuit. The PDC plane-to-plane DBD equivalent circuit simulated the actual phase difference of plasma voltage and current. And we will design the tunable impedance matching circuit based on the structure of parallel impedance matching circuit. Previous studies proposed that an installation of impedance matching circuit between power supply and plasma can effectively increase the system power conversion efficiency. However, the adopted plasma equivalent circuit in the previous study may not consider the partial discharge phenomenon of DBD in atmospheric pressure and the phase difference between plasma voltage and current. Under atmospheric pressure, the charge does not distribute uniformly on the dielectric, so the discharge channels only generated on part of the dielectric area. Therefore, the impedance of plasma equivalent circuit may not correspond to the actual plasma impedance, and it result in an inaccurate impedance matching circuit design. In this study, we measured Q-V diagram to construct the PDC plasma equivalent circuit that can simulate the partial discharge phenomenon of atmospheric-pressure plasma, and the PDC plasma equivalent circuit is contributed to the corresponding impedance matching circuit design. For tunable impedance matching circuit design, we will design a system to control the variable capacitor for the tunable parallel matching circuit. As a result, the plasma discharging area ratio of 0.8275 was deduced from the slope of Q-V diagram and the PDC atmospheric-pressure plasma equivalent circuit was successfully established. Then we used Simulink software to calibrate the resistor of PDC plasma equivalent circuit for accurate phase shift. Through the phase difference calculation, the error of phase difference between simulation and measurement results was 1.01 degree. And a power supply equivalent circuit was also established by measuring the no-load voltage of power supply. The accurate PDC plasma equivalent circuit was then applied for more precise impedance matching circuit calculation under atmospheric pressure. Then we will check if the power conversion efficiency is enhanced with the installation of impedance matching circuit for PDC plasma equivalent circuit or not. Plasma impedance may be affected by different working gases, discharge gaps, dielectric materials, and operation voltage frequency. Therefore, the application of tunable impedance matching circuit will ensure the maximum power transmission under different plasma working conditions.
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Dabby Lu,
2020年11月19日 下午7:06
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