EAST 四条带ICRF 天线的三维电磁场分析

采用3 维电磁场代码CST MWS 对EAST 4 条带的离子回旋(ICRF)天线性能进行模拟研究,分析了天线的耦合阻抗随频率的变化,计算了电流和波谱的分布,模拟研究了不同电流相位对天线的电压击穿打火和引入杂质的影响。计算结果表明：此EAST 的ICRF 天线耦合阻抗和波谱总体设计合理;但天线局部电场较高,当环向电流条带为(0, 0, 0, 0)相位时E_max 为3.61MV•m⁻¹ 超出击穿阈值,经过结构尺寸的优化后E_max 低于阈值。同时表明天线运行时限制器处有较高的RF 电势,当电流相位为(0, π, π, 0)时法拉第屏前10mm 处的RF 电势是(0, 0, π, π)相位时的1/3。     

频率调制对ICRH 天线阻抗匹配的影响研究

采用三支节液态调配器使离子回旋加热(ICRH)天线系统达到阻抗匹配,在阻抗匹配的条件下结合频率调制技术来减小由天线输入阻抗变化所引起的反射功率。数值模拟了频率调制前后天线负载与反射系数的变化关系,用来验证频率调制对ICRH 天线中阻抗匹配装置的影响。模拟结果表明：三支节液态调配器结合频率调制方法,能更好地降低天线传输系统的反射系数,使得发射机的功率通过天线辐射更加有效地耦合到等离子体中去。     

Theoretical analysis of the EAST 4-strap ion cyclotron range of frequency antenna with variational theory

A variational principle code which can calculate self-consistently currents on the conductors is used to assess the coupling characteristic of the EAST 4-strap ion cyclotron range of frequency(ICRF) antenna. Taking into account two layers of antenna conductors without lateral frame but with slab geometry, the antenna impedances as a function of frequency and the structure of RF field excited inside the plasma in various phasing cases are discussed in this paper.     

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采用三支节液态调配器使离子回旋加热(ICRH)天线系统达到阻抗匹配,在阻抗匹配的条件下结合频率调制技术来减小由天线输入阻抗变化所引起的反射功率。数值模拟了频率调制前后天线负载与反射系数的变化关系,用来验证频率调制对ICRH天线中阻抗匹配装置的影响。模拟结果表明:三支节液态调配器结合频率调制方法,能更好地降低天线传输系统的反射系数,使得发射机的功率通过天线辐射更加有效地耦合到等离子体中去。     

光电导天线辐射阻抗特性模拟分析(英文)

针对连续太赫兹光电导天线辐射功率较低的缺点,利用有限积分方法对三种常用的光电导天线,包括偶极天线、蝶形天线和螺旋天线,进行数值模拟并分析比较其辐射阻抗特性.仿真结果表明,偶极天线的辐射阻抗与偶极长度、宽度、电极间隙以及传输线宽度有关,且在其谐振频率存在峰值阻抗,适用于特定频率的太赫兹波辐射.蝶形天线和螺旋天线在所研究的太赫兹波段具有近似稳定的辐射阻抗,广泛应用于宽带领域.对带有交叉电极的电极间隙进行计算,结果表明由交叉电极引入的附加电容降低了天线的高频阻抗.     

HIRFL注入器高频腔体与高频机的匹配

 叙述了兰州重离子加速器注入器(SFC)高频系统的200 kW高频机与高频腔体的功率匹配，匹配测量系统的工作原理，以及对匹配系统的改进和完善，并对高频腔体的输入阻抗和耦合电容进行了计算。为提高高频系统的稳定性和可靠性，对影响高频功率传输和D电压提高的问题进行了深入的研究和改进。采用矢量阻抗仪冷态测量腔体匹配阻抗的方法和一些相应的技术和措施，用矢量电压表动态测量功率输出级的相位差，判断D电路是否工作在匹配状态，从而使SFC的D电压由原来的50~65 kV（不稳定）提高到稳定工作的105 kV，改善了SFC的工作状态和保证了SFC的高效运行。     

Antenna coupling study for ICWC plasma characterization in TEXTOR

Ion cyclotron wall conditioning (ICWC) discharges, in pulsed-mode operation, were carried out in the limiter tokamak TEXTOR to explore safe operational regimes for the experimental parameters for possible ICWC-discharge cleaning in International Thermonuclear Experimental Reactor (ITER) at half field. Antenna coupling properties obtained during the ion cyclotron range of frequencies (ICRF) wall conditioning experiments performed in helium–hydrogen mixture in TEXTOR were analysed in relation to the obtained ICWC-plasma characterization results. Satisfactory antenna coupling in the mode conversion scenario along with reproducible generation of ICRF plasmas for wall conditioning, were achieved by coupling radio frequency (RF) power from one or two ICRF antennas. The plasma breakdown results obtained in the TEXTOR tokamak have been compared with the predictions of a zero-dimensional RF plasma production model. The present study of ICWC emphasizes the beneficial effect of application of an additional (along with toroidal magnetic field) stationary vertical (B _V???B _T) or oscillating poloidal magnetic field (B _P???B _T) on antenna coupling and relevant plasma parameters.     

Operating modes of relativistic rising-sun and A6 magnetrons

The operating characteristics of a relativistic 16-vane rising-sun magnetron were investigated with particular emphasis on determining the operating regimes of different modes. The magnetron performance was studied as a function of voltage, magnetic field, cathode geometry, axial boundary conditions, and output coupling. Operation was observed in the 3π/8 mode at 3.3 GHz, in the π/2 or 3π/8 mode at 3.5 GHz, and in the π or 7π/8 mode at 4.6 GHz. A maximum power of 80 MW was emitted in the 3π/8 mode with an efficiency of 4.5%. Typical pulse lengths were 40-50 ns. Cold tests were performed to measure the resonant frequencies and azimuthal electric fields in the interaction space which agreed within 1-4% of theoretical calculations. The operating modes were inferred from close agreement between hot-test frequencies and cold-test results and because high-power RF emission occurred at, or just above, the Buneman-Hartree threshold calculated for these modes. The characteristics of a six-vane A6-magnetron operating in the π and 2π modes were also studied. A unique transmitting-receiving system, which was used as a microwave diagnostic, is described     

Theoretical analysis of ion cyclotron range of frequency antenna array for HT-7U

This paper considers the coupling analysis of phased antenna array designed to excite fast wave in the ion cyclotron range of frequency. The coupling of the antenna is calculated in slab geometry. The coupling code based on the variational principle gives the self-consistent current flowing in the antenna, this method has been extended so that it can be applied to a phased antenna array. As an example, this paper analyses the coupling prosperities of a 2 × 2 phased antenna array. It gives the optimum geometry of antenna array. The fields excited at plasma surface are found to more or less correspond to the antenna current phasing.     

ICRH Antenna Array Analysis and Resulting Problem of Generator Matching

A model for arrays of ion cyclotron resonance heating (ICRH) antennae is presented, each antenna being fed by a separate generator with its own tuning system. In view of wave spectrum shaping, arbitrary phasing is introduced between the generators. The array is analyzed in quasi-TEM modes, and its equivalent impedance matrix is derived. In the case of an antenna pair, we study the matching of both generators, which becomes quite involved due to the strong coupling between antennae, and we investigate the consequences of tuning errors on the whole system.