The pulsatile electroosmotic flow （PEOF） of a Maxwell fluid in a parallel flat plate microchannel with asymmetric wall zeta potentials is theoretically analyzed. By combining the linear Maxwell viscoelastic model, t...The pulsatile electroosmotic flow （PEOF） of a Maxwell fluid in a parallel flat plate microchannel with asymmetric wall zeta potentials is theoretically analyzed. By combining the linear Maxwell viscoelastic model, the Cauchy equation, and the electric field solution obtained from the linearized PoissomBoltzmann equation, a hyperbolic par- tial differential equation is obtained to derive the flow field. The PEOF is controlled by the angular Reynolds number, the ratio of the zeta potentials of the microchannel walls, the electrokinetic parameter, and the elasticity number. The main results obtained from this analysis show strong oscillations in the velocity profiles when the values of the elas- ticity number and the angular Reynolds number increase due to the competition among the elastic, viscous, inertial, and electric forces in the flow.展开更多
Microchannel plates (MCP) are widely used for particle detection. The gain of chevron MCPs is related to geometrical parameters, but no study has been done through SIMION simulation. The purpose of this study is to mo...Microchannel plates (MCP) are widely used for particle detection. The gain of chevron MCPs is related to geometrical parameters, but no study has been done through SIMION simulation. The purpose of this study is to model a chevron MCP and its secondary emission process using SIMION and determine the relationship between microchannel plate gain, voltage, channel bias angle, and diameter. Two geometry files simulated MCP electric field and shape, and a Lua program simulated secondary emission. Simulation results showed that MCP gain is proportional to voltage, angles between 5 and 15 degrees maximize gain, and gain is inversely proportional to the diameter. This study accurately simulates a chevron MCP and yields the relationship between gain, voltage, channel bias angle, and diameter. Further studies are needed to simulate electron trajectories for improved precision.展开更多
为了满足Φ30 mm MCP大束流短时间电子清刷新工艺要求,以轴向电子枪工作原理为基础,利用静电场对电子的作用理论,分析了电子的运动轨迹,并对电子的偏转进行了计算。根据计算结果,设计了电子枪的基本结构,确定了电子枪的各种参数:灯丝材...为了满足Φ30 mm MCP大束流短时间电子清刷新工艺要求,以轴向电子枪工作原理为基础,利用静电场对电子的作用理论,分析了电子的运动轨迹,并对电子的偏转进行了计算。根据计算结果,设计了电子枪的基本结构,确定了电子枪的各种参数:灯丝材料为Φ0.05 mm的钨(75%)铼(25%)合金丝;灯丝形状为"∨"字型;电子枪外径为Φ35 mm,高度为20 mm,最大加热功率为12.6 W时,电子发射电流密度达到1.26×10-5A/cm2。用该电子枪对4块性能相近的Φ30 mm MCP电子清刷4 h后,MCP的增益值达到500±50。这表明:用新电子枪可以代替原RUS-A型电子枪。展开更多
基金Project supported by the Fondo Sectorial de Investigación para la Educación from the Secretar a de Educación Pública-Consejo Nacional de Ciencia y Tecnología(No.CB-2013/220900)the Secretaría de Investigación y Posgrado from Instituto Politécnico Nacional of Mexico(No.20171181)
文摘The pulsatile electroosmotic flow （PEOF） of a Maxwell fluid in a parallel flat plate microchannel with asymmetric wall zeta potentials is theoretically analyzed. By combining the linear Maxwell viscoelastic model, the Cauchy equation, and the electric field solution obtained from the linearized PoissomBoltzmann equation, a hyperbolic par- tial differential equation is obtained to derive the flow field. The PEOF is controlled by the angular Reynolds number, the ratio of the zeta potentials of the microchannel walls, the electrokinetic parameter, and the elasticity number. The main results obtained from this analysis show strong oscillations in the velocity profiles when the values of the elas- ticity number and the angular Reynolds number increase due to the competition among the elastic, viscous, inertial, and electric forces in the flow.
文摘Microchannel plates (MCP) are widely used for particle detection. The gain of chevron MCPs is related to geometrical parameters, but no study has been done through SIMION simulation. The purpose of this study is to model a chevron MCP and its secondary emission process using SIMION and determine the relationship between microchannel plate gain, voltage, channel bias angle, and diameter. Two geometry files simulated MCP electric field and shape, and a Lua program simulated secondary emission. Simulation results showed that MCP gain is proportional to voltage, angles between 5 and 15 degrees maximize gain, and gain is inversely proportional to the diameter. This study accurately simulates a chevron MCP and yields the relationship between gain, voltage, channel bias angle, and diameter. Further studies are needed to simulate electron trajectories for improved precision.
文摘为了满足Φ30 mm MCP大束流短时间电子清刷新工艺要求,以轴向电子枪工作原理为基础,利用静电场对电子的作用理论,分析了电子的运动轨迹,并对电子的偏转进行了计算。根据计算结果,设计了电子枪的基本结构,确定了电子枪的各种参数:灯丝材料为Φ0.05 mm的钨(75%)铼(25%)合金丝;灯丝形状为"∨"字型;电子枪外径为Φ35 mm,高度为20 mm,最大加热功率为12.6 W时,电子发射电流密度达到1.26×10-5A/cm2。用该电子枪对4块性能相近的Φ30 mm MCP电子清刷4 h后,MCP的增益值达到500±50。这表明:用新电子枪可以代替原RUS-A型电子枪。
