摘要
采用锆钛酸铅(PZT)铁电阴极,在高真空4×10-3Pa和低真空1.4Pa条件下分别进行了电子发射实验。对收集电流波形进行积分,计算出收集电荷,低真空与高真空的电荷比值为0.1933,说明低真空条件下发射出的电子损失较大。运用分子运动理论和等离子体放电理论对发射电子损失的原因进行了分析。通过分子运动理论计算了分子碰撞对到达收集极的电子数目的影响,得到的低真空与高真空的电子到达几率分别为89.58%和99.97%,二者的比值为0.8961。该数值与通过实验收集电流波形计算出的到达电子比值相差很大。考虑低真空下等离子体的作用,发射电子除了与气体分子碰撞有部分损失外,还有通过等离子体和栅电极形成的对地放电损失。由等离子体放电理论计算出等离子体覆盖栅电极时间为23.8ns,与低真空的收集电流振荡周期20ns非常接近,是低真空下等离子体放电损失的有力证明。
The electron emission experiments on PZT cathode were done under high pressure of 4 × 10^-3 Pa and low pressure of 1.4 Pa. The number of collected electrons was given by integrating the curve line of collected current. The ratio of collected electrons under low pressure and high pressure is 0. 193 3 and it can be drawn that many electrons emitted from the cathode were lost under low pressure. The reasons why electrons were lost were analyzed based on the theory of molecular motion and plasma discharge. The probability of electrons which can reach anode after collision with the gas molecular can be calculated through theory of molecular motion. The value are respectively 89.58% and 99.97 % under low and high pressure, thus the ratio is 0. 896 1 which is far away from the ratio calculated from collected current. Only a little fraction of the emitted electrons were lost due to the collision with the gas molecular, but more due to the plasma discharge through the grid electrode as the plasma should be considered under low pressure. The time that the grid electrode was covered by the plasma is 23.8 ns based on plasma discharge theory, which is near to the periodic time 20 ns observed from the waveforms of the collected current. Thus it can be testified that the palsma discharge is the main reason for the losing of electrons under low pressure by the above results.
出处
《液晶与显示》
CAS
CSCD
北大核心
2009年第2期174-178,共5页
Chinese Journal of Liquid Crystals and Displays
基金
重庆市自然科学基金资助(No.CSTC2008BB4408)
关键词
铁电阴极
分子运动论
等离子体放电
ferroelectric cathode
theory of molecular motion
plasma discharge
