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理学院“博约学术沙龙”系列报告 (总第 142期)

发布日期:2017年11月06日
时间:2017年11月6日(星期一)下午14:30
地点:中心教学楼610
报告一:硕士生报告    时间:14:30-15:00
题目:大气压等离子体射流自脉冲实验研究
Experimental study on self-pulsing in flow-induced atmospheric pressure plasma jet
报告人:崔瑞林          指导教师:欧阳吉庭 缪劲松
Abstract :In this paper, we present experimental study on the self-pulsing phenomenon in flow-induced atmospheric pressure plasma jet (APPJ) in a hollow electrode configuration driven by DC voltages. The current-voltage curves, the typical waveforms of the self-pulsing current and voltage, the time-resolved images and the repetition frequency were measured under different experimental conditions. The results show that the APPJ of hollow electrode can sustain in a mode of stable, repeatable self-pulsing regime. The waveform of the pulsed current is very stable with nearly constant rising time and decay time at different discharge averaged current. But the pulse interval (also the pulsing frequency) depends on discharge conditions. The pulsing frequency increases linearly with the averaged current and the gas flow rate, but decreases with the electrode gap. The time-resolved images recorded by ICCD camera show that the pulsed jet contains the process of breakdown, development and decay of a glow discharge. There is also a weak discharge during the pulse interval. It indicates that the self-pulsing in this APPJ is a mode transition of discharge between glow and weak discharge. An equivalent electric circuit containing a variable resistance and capacitor can well describe the self-pulsing.
Key Words: APPJ (atmospheric-pressure plasma jet); self-pulsing; equivalent electric circuit
报告二:硕士生报告    时间:15:00-15:30
题  目:介质管对大气压共面DBD等离子体射流传播的影响
Numerical study of the influence of dielectric tube on propagation of atmospherepressure plasma jet based on coplanar dielectric barrier discharge
报告人:胡海欣                指导老师:欧阳吉庭

Abstract: A two-dimensional fluid model was employed to simulate the influence of dielectric on the propagation of atmosphere pressure helium plasma jet based on coplanar dielectric barrier discharge (DBD). The spatio-temporal distributions of electron density, ionization rate, electrical field, spatial charge and the spatial structure were obtained for different dielectric tube that limits the helium flow. The results show that the change of the relative permittivity of dielectric tube where the plasma jet travels inside has no influence on the formation of DBD itself, but has great impact on the jet propagation. The velocity of plasma jet changes drastically when the jet passing from a tube of higher permittivity to a lower one, resulting in an increase in the ionization rate, electric field, jet length, as well as a change in the distribution of space charges and discharge states. The radius of dielectric tube has great influence on the bullet structure of hollow or solid one. This results can well explain the behavior of plasma jet from the dielectric tube into the ambient air and the ring-shaped bullet in experiments.
报告三:硕士生报告    时间:15:30-16:00
题  目: 全溶液法制备FET结构的PbS量子点光电探测器
报告人:王琦                指导老师:杨盛谊

摘要:胶体量子点具有荧光光谱可调、量子产率高、载流子迁移率大和吸收系数大等特点而被广泛应用于光电器件领域。与常见的用Si/SiO2作为栅极和绝缘层的场效应晶体管器件相比,本文中我们采用全溶液法来制备基于基于场效应晶体管结构的胶体量子点近红外光电探测器。采用热注入法合成的PbS量子点作为有源层,采用溶胶-凝胶法制备的SiO2作为绝缘层,利用简单的旋涂法制备光电探测器。通过对SiO2材料的脱水处理与热固化处理,SiO2在量子点材料上形成一层致密的薄膜,该绝缘层单位电容达到9.8nF/cm2。与传统的Si/SiO2作为栅极和绝缘层相比,这种方法制备的器件没有太大的衰减,依然表现出较好的效率和稳定性。采用该方法制备的器件具有低成本、易加工和具有普适性等优点,商业应用前景广阔。此外,研究了PbS量子点膜厚及其表面处理、以及SiO2膜厚对器件性能的影响,得到理想的器件结构和器件性能, 当光功率密度为0.21mW/cm2时,器件的响应度R和比探测率D*分别达到最大,其数值为76.3 mA/W和1.06*1010 Jones,并且经过计算也可知此时的明暗电流比为16.4。

 

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