【作者】 程健；

【导师】 赵燕平； 陈根；

【作者基本信息】 中国科学技术大学 ， 等离子体物理， 2020， 博士

【摘要】 EAST实验期间,离子回旋共振加热的微波天线每条电流带耦合阻抗的变化范围为1-5Ω,而离子回旋波加热系统中所用传输线的特性阻抗和发射机的输入阻抗都为50Ω,通过传输线将发射机的输出功率直接加载在天线的电流带上,势必会导致系统的反射功率极大。在EAST离子回旋波加热系统中,原有的匹配装置为三支节液态调配器,由于历史原因导致三支节液态调配器距离天线较远。在EAST实验期间,天线阻抗的变化,使二者之间的传输线承受着高驻波电压,导致传输线打火的现象经常发生,并难以查找打火点。针对此问题,本文提出一种新型匹配装置,名为共轭-T匹配,近天线安装,用来辅助或取代原有的三支节液态调配器,改善传输线经常出现打火的情况。共轭-T系统的特点是可将一台发射机的功率加载在两条电流带上,并使连接了特定长度传输线的两条电流带在T点处的输入阻抗的实部相等,虚部相反,最终实现共轭。本文中通过数值模拟和软件仿真分析了简单共轭-T系统,复杂共辗-T系统和直接匹配式共轭-T系统共三种共轭-T模型。数值模拟主要是对单套共轭-T系统的性能进行全面的分析,软件仿真是通过仿真软件来分析两套共轭-T系统在存在功率耦合情况下系统的性能。数值模拟发现共轭-T系统内的负载实部存在差异对系统的反射功率影响较小,但负载中引入的虚部会造成系统反射功率的急剧增加。通过软件仿真发现,单套共轭-T系统的性能在存在功率耦合的情况下基本得到保持,但是两套共轭-T系统之间存在着较强的功率耦合。针对两套共轭-T系统之间存在着功率耦合的情况,在基于共轭-T的匹配网络中建立了一套解耦装置。另外为了保障共轭-T实验的正常进行,还开发了同轴开关网络的控制系统。相关的实验验证了单套直接匹配式共轭-T系统的可行性,但两套共轭-T系统之间建立的解耦装置并不能保证两套共轭-T系统在高功率模式下工作。通过讨论分析此种情况可能发生的原因,并计划进行实验验证。更多还原

【Abstract】 During the EAST experiment,the variation range of strap impedance of the antenna is 1-5Ω.However,both the characteristic impedance of the transmission line used in the ion cyclotron resonance heating(ICRH)system and the input impedance of the transmitter are 50Ω.The output power of the transmitter is directly loaded on the current strap of the antenna through the transmission line,which will inevitably lead to the extremely large power coefficient of the system.To solve this mismatch problem,a matching system was designed in EAST,and the original matching device is three liquid stub tuners.Due to historical reasons,three liquid stub tuners is installed far from the antenna.During the EAST experiment,the transmission line between the antenna and the three liquid stub tuners endures a high standing wave voltage,which leads to frequent arcing on the transmission line,and it was difficult to find the arcing position.To address this problem,a new type of matching,called conjugate-T matching,is proposed and installed near the antenna.It is used to assist or replace the three liquid stub tuners to reduce the risk of arcing on the transmission line.The characteristic of the conjugate-T system is that it can make the power of a transmitter load on two straps,and the real part of the input impedance of point T on the two straps are equal,and the imaginary part is opposite.In this thesis,three conjugate-T models are analyzed through numerical and software simulation,including simple conjugate-T system,complex conjugate-T system and direct matching conjugate-T system.Numerical simulation is mainly to conduct a comprehensive analysis of the performance of one conjugate-T system,and software simulation is to analyze the performance of two sets of conjugate-T systems in the presence of power coupling.Through numerical simulations,we can conclude that the difference in the real part of the load in the system has less impact on the reflected power of the system,while the imaginary part of the load will cause dramatic increase in the reflected power of the system.Through software simulation,it is found that the performance of the conjugate-T system is basically maintained in the presence of power coupling,but the between two sets of conjugate-T systems,strong power coupling exists.For this issue,a decoupler is established in the matching network based on conjugate-T.In addition,in order to ensure the normal progress of the conjugate-T experiment,a coaxial switch control system was also developed.Experiments have verified the feasibility of a single directly matched conjugate-T system,but the decoupler established between two conjugate-T systems does not guarantee the smooth work of the two conjugate-T systems in high power mode.Discussion and analysis of the possible causes for this situation has been done,and experimental verification is planned.更多还原