To make pic ( particl - in - cell ) simulations . to set up models of guns and magnetic field and simulate them in the vacuum and plasma , respectively . we found that plasma held back part of space charge effects and improved trajectory of electrons . but beam would oscillate and became instable as accretion of plasma density . by simulating again and again , we draw a conclusion magic could n ' t work when plasma density was more by far than beam electron density . at last a four - stage depressed collector was simulated 建立电子枪和聚焦系统模拟模型,分别在真空和填充等离子体条件下进行模拟。发现填充等离子体能补偿部分空间电荷效应,改善电子束包络轨迹,提高电子的流通率,但是随着等离子体密度的增大,束电子会出现振荡不稳定性,遗憾的是通过反复多次模拟发现本文所用粒子模拟的代表性软件magic无法用于模拟等离子体密度远高于束电子密度的情况。
Based on sndm technique , a method of local capacitance - voltage characteristic characterization of ferroelectric thin films was proposed . the effect of traps at oxide - semiconductor interface on metal - oxide - semiconductor structure capacitance - voltage curve was discussed , and the influence of coercive field to the capacitance - voltage characteristics of ferroelectric thin films was also discussed . the dynamic switching of ferroelectric domain in ca doping ( pb , la ) tio3 thin film was studied by sndm from the view of electricity 利用sndm ,从纯电学的角度观察了plct薄膜中的电畴动态反转过程,由电畴横向扩张的移动速度的降低,发现了晶界在电畴反转过程中对畴壁移动的阻挡作用;根据sndm和pfm的在垂直方向上的不同信息敏感深度,得到plct薄膜中电畴反转过程中电畴是楔形畴;用pfm观察同一电畴在去掉外加反转电场后电畴的极化弛豫现象,结果表明空间电荷是发生极化弛豫的主要原因。
One of effective ways of overcoming space charge effect is to fill plasma in high power wave apparatus , by the neutralization between plasma and space charge , the transfer current is going to be largely enhanced , thereby out - power is going to be largely increased . meantime , due to there are many fluctuating modes in plasma , so it is able to bring a new beam - wave interaction mechanism , by it people can invent some new type high power microwave apparatus 高功率微波装置中的电流密度很大,空间电荷效应强烈,影响了功率的提高,克服空间电荷效应的有效方法是在高功率微波器件中填充等离子体,由于等离子体对空间电荷的中和作用,传输电流会大大提高,从而大幅度提高输出功率,同时由于等离子体中存在多种波动模式,有可能带来新的注波互作用机制,发展新型的高功率微波器件。
In order to obtain the tolerance requirement for the magnetic field homogeneity of the solenoids in electron cooling device , the source of the magnetic imperfection and its influence on the transverse temperature of electron beam were investigated by means of numerical simulation , and taking the space charge effect of electron beam into account 摘要分析了直螺线管磁场缺陷的来源，考虑了电子束的空间电荷作用，采用数值方法模拟计算了磁场缺陷对电子束横向温度的影响，获得了电子冷却装置中直螺线管磁场的均匀性要求。
The mode competition is much improved . it may operated with a large electron beam radius , that means decreasing the space charge effects compared with a smaller radius beam with the same current , hence the rbwo may operated with a low axial guide magnetic field . besides , the rbwo with a sinusoidal corrugated coaxial structure is very easy to manufacture 波纹内导体rbwo具有一些突出优点:同轴结构中内导体的存在使系统的截止频率显著升高,使得系统尺寸可比普通波纹波导慢波系统大;具有很大的抑制模式竞争的能力和很高的功率容量;可以采用大半径电子注,在工作电流不变的情况下空间电荷效应大幅度降低,因而可以工作在低磁场状态;此种慢波结构内导体上的波纹易于加工。
