EAST 装置离子回旋加热液态阻抗匹配系统的研究

介绍了EAST 装置离子回旋加热系统中的两种实现阻抗匹配的方式, 用三支节液态调配器取代传统的滑竿式三支节调配器和用液态相移器与单支节液态调配器相结合组成液态阻抗匹配系统。通过对液态阻抗匹配系统的分析, 表明这两种方式都能够较好地实现阻抗匹配。     

C-ADS强流质子直线加速器调谐系统测试分析

调谐系统是C-ADS超导直线加速器不可或缺的一部分, 在加速器运行过程决定了超导腔的运行频率, 直接影响了粒子加速的效果。为了充分了解调谐系统的工作情况和分析调谐系统出现的问题, 设计了实验对调谐系统进行全方位测试。首先对调谐器的杠杆机构和剪叉机构进行了力学分析, 而后对半波长谐振(HWR) 超导腔在不同状态下进行了电场模拟, 得出设计的调谐力和调谐位移满足HWR腔频率调谐要求。最后通过详细实验, 采用自动、手动等方式测试了恒温器CM1, CM2, CM3中超导腔调谐器工作时的线性度、回程差、直线单元部分的线性度及回程。结果显示: CM1的调谐器基本满足慢调谐需要, CM2存在1200步回程, 主要原因在于直线单元部分; CM3中调谐器的回程差较大, 线性度不高, 需要进一步改进。     

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介绍了EAST上ICRF辅助加热系统1.5MW射频信号源中工作频率为25～70MHz的末级功率放大器的研制工作,从最优工作参数、输入回路和输出回路三个主要方面详细分析了该级大功率宽频带射频放大器。经比较,分析结果和测试数据显示了很好的一致性,这为实现ICRF加热系统的可靠运行奠定了基础。     

EAST ICRF天线移动结构设计

根据EAST物理实验要求,EAST ICRF天线被设计成带有一种沿着EAST装置径向方向移动的液压驱动导轨式结构.为了验证移动结构的可行性,对ICRF天线移动结构支撑部件通过公式和有限元方法进行了相关的计算分析,分析结果满足设计要求.对ICRF天线整体结构进行了受力分析以及对装配好的ICRF天线移动结构进行了调试,受力...     

Preliminary result of an advanced tangential X-ray pinhole camera system with a duplex MWPC on KSTAR plasma

An advanced tangential X-ray pinhole camera (TXPC) has been developed for KSTAR by utilizing a 2-D duplex multi-wire proportional counter (MWPC) detector. The KSTAR MWPC employs a 2-D parallel type readout system for high temporal resolution and adopts a duplex type for the capability of electron temperature measurement via the multi-color method. This paper presents the performance test result of the developed MWPC system utilizing a Fe-55 X-ray source. As a preliminary experimental result from the 2012 KSTAR campaign, the clear presentation of sawtooth activities and its frequency change, and 2-D plasma images during the vertical disruption event are given.     

Design and test of frequency tuner for a CAEP high power THz free-electron laser

Peking University is developing a 1.3 GHz superconducting accelerating section highpower THz freeelectron laser for the China Academy of Engineering Physics(CAEP). A compact fast/slow tuner has been developed by the Institute of High Energy Physics(IHEP) for the accelerating section to control Lorentz detuning, compensate for beam loading effect, microphonics and liquid helium pressure fluctuations. The tuner design, warm test and cold test of the first prototype are presented, which has a guiding significance for the manufacture of the formal tuner and cryomodule assembly.     

Coupling Analysis for the ICRF Resonant Cavity Launcher on DIII-D

The coupling properties of the ion-cyclotron range of frequencies (ICRF) resonant cavity launcher for DIII-D were investigated with a two-dimensional (2-D) model. In the context of the magnetostatic approximation, Poisson's equation was solved for the vector potential with a self-consistent antenna current distribution. The tool of analysis is a fast 2-D Poisson solver which takes into account the plasma medium and the shape of the cavity wall and antenna cross section. This permits the design of the optimum configuration for such a launcher to be used on the DIII-D tokamak. Extensive parametric studies of the launcher loading impedance were carried out. It was found that the antenna-plasma distance and the edge density gradient are the two most critical parameters determining the coupling. Criteria were also established to optimize the power-handling properties of the cavity coupler.     

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鉴于EAST ICRF天线真空密封性和基于实验移动的要求,可移动支撑被设计用来支撑ICRF天线前部重量。通过理论计算公式对天线支撑结构进行计算,给出了不同截面尺寸、不同移动距离下支撑杆应力和变形情况。用有限元分析方法进行分析,分析结果和理论公式计算结果非常相近,满足设计要求。计算结果为支撑杆优化设计提供理论指导,计算方法为同类装置的支撑结构提供有益的借鉴。     

Prism tuner for single frequency operation of CW dye laser

A cw dye laser capable of single longitudinal mode operation and linear reproducible wavelenght tuning over a relatively wide spectral range is described. By employing a novel scheme of four intracavity highly dispersive Abbe prisms output powers of 5 mW with a linewidth less than 30 MHz for an input power of 700 mW have been obtained.     

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The performance of the four strap ion cyclotron range of frequency (ICRF) antenna in EAST was studied by three dimensional electromagnetic code CST MWS. The coupling impedance with various frequencies, the distribution of current on straps and the power spectra for the three types of phases were calculated. The voltage breakdown and ICRF-related impurity were also studied. Simulation results show that the coupling impedance and power spectrum of the antenna design were reasonable, however, highest electric field, which is 3.61MV•m⁻¹ for (0, 0, 0, 0) toroidal phasing at the local area, exceeds the empirical value of breakdown. After the structure size was optimized, the maximum of E-field was below the breakdown value, the results also show that the high radio frequency (RF) potential was close to the antenna limiter, the RF potential along total B-field in front of Faraday screens 10mm for (0, π, π, 0) phasing was one-third of that for (0, 0, π, π) phasing.     

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。     

一种大口径无液氦低温超导磁体系统的研制

将铜和不锈钢材料制作成Φ646mm×1175mm大口径低温超导磁体复合骨架,骨架两端设计有传热热桥。选用1.5W@4.2K的G-M制冷机作为冷源,采用高导热的无氧铜编织带作为制冷机二级冷头和传热热桥之间的柔性连接件,来实现柔性传热。经过124h后,实现了低温超导磁体系统的冷却。超导磁体闭环运行后,磁场强度达到设计值,均匀区内不均匀度优于指标要求。     

An analysis of the folded waveguide: a compact waveguide launcherfor ICRF heating

Theoretical and experimental investigations of the folded waveguide launcher as proposed for use in the ion-cyclotron range of frequencies (ICRF) heating of tokamak plasmas are presented. Theoretical results include an analysis of the folded waveguide using Ritz's method to obtain various field quantities. The cutoff wavenumbers from this analysis are within 10% of those calculated using an unfolded equivalent rectangular waveguide model. Measurements of cavity resonances for a scale-model ICRF-folded waveguide with a cutoff frequency of 2.4 GHz also agree closely with those calculated using an unfolded equivalent model. An unfolded equivalent waveguide model is used to evaluate the properties of an inductive strip placed in the folded waveguide. Applying variational analyses provides upper and lower bounds to the reflection magnitude |S₁₁| that are in good agreement with measured values. Polarizing plates (which have been proposed to increase the on-axis directivity of the radiated power) are modeled using an unfolded equivalent waveguide. A variational analysis is used to determine an upper-bound value of |S₁₁| in air due to a polarizing plate inside a matched folded waveguide. Measured values are found to be within 3% of the calculated values, with |S₁₁|>0.95 for frequencies between 2.5 and 4.5 GHz     

Development of discharge in a system of electrodes situated on interface of liquid and solid dielectrics

The development of a discharge in the case where the electrodes are situated at the interface of solid and liquid dielectrics was investigated with the aid of an apparatus based on two photomultipliers and an electrolytic tank. In these conditions the discharge develops along a single pathway, which runs along the interface for part of its length and then passes into the solid dielectric. Possible factors that predetermine the pathway of the spark channel in the considered system of electrodes and dielectrics are examined.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 61–66, September, 1978.     

EAST ICRF天线法拉第屏蔽的电磁分析

法拉第屏蔽是EAST 装置 ICRF天线的一个重要部件。鉴于法拉第屏蔽的结构安全性,通过运用有限元方法和公式对法拉第屏蔽在等离子体破裂和等离子体垂直位移事件两种工况下进行电磁和结构分析,获得了法拉第屏蔽在这两种工况下所受的电磁力、应力分布和变形情况。分析结果满足设计要求,并为法拉第屏蔽的结构安全性评估提供理论依据。     

Thermal modes of a plug flow reactor with a liquid–liquid heterogeneous system

The thermal modes of a flow plug reactor with an exothermic chemical reaction are numerically simulated. A heterogeneous reaction system consisting of two immiscible liquids is studied: one of the liquids (dispersed phase) in the form of droplets is distributed in the other (dispersion phase). The characteristics of the thermal modes of the reactor at various values of two governing parameters, the Damköhler number and the rate of extraction of the dissolved substance from the dispersed phase into the dispersion phase is examined. Two modes of chemical reaction in the reactor are demonstrated to be possible: low-temperature and high-temperature. Critical criteria of thermal ignition are formulated. The dependence of the structure of the thermal wave on the governing parameters is investigated.     

Analysis of Dielectrc-Filled Waveguide Coupling to Plasmas in the ICRF

Dielectric-filled waveguides may be advantageous for heating reactor-grade tokamak plasmas, due to their compactness and power-handling capability. We present a theoretical analysis of coax excitation and plasma impedance for a dielectric-filled rectangular waveguide. The plasma reflection coefficient is obtained by matching plasma and waveguide fields at the interface. The numerical results show that the reflection coefficients can be made small by careful tailoring of the waveguide dimensions to the density profile for heating at the second or third harmonic of deuterium. We present a scattering matrix approach for the design of a coaxial feed to match the waveguide in the presence of a wide range of plasma loading. For a waveguide filled with a high permittivity dielectric, a shorted probe gives better coupling than an open-ended probe.     

Polysulfone as polymer matrix for a novel polymer-dispersed liquid crystals system

We report the preparation and thermotropic characterization of a novel polymer-dispersed liquid crystal (PDLC) system based on the polysulfone (PSU) UDEL-1700 as a polymer matrix and on 4-[4-(n-butyloxy)phenylene-imino-methylidene]benzonitrile as a liquid crystal. PDLC films have been prepared using the thermal-induced phase separation (TIPS) technique, with different compositions in the two components. A detailed optical polarized microscopy and differential scanning calorimetry study has been carried out to evaluate a correlation between the composite composition and the PDLC formation. We found that PSU could be a good matrix for the formation of PDLC systems.     

Study of Power Coupling through an Electrostatic Shield on a Loop Antenna for ICRF Heating of EBT-S

The effects of electrostatic shields around the antenna used for ICRF heating in the EBT-S fusion experiment on the efficiency of power transfer from the antenna to the plasma were studied in bench tests using resonant coupling loops placed near the antenna to simulate plasma behavior. For the frequency range of interest in these experiments, the length of the antenna was much shorter than the free-space wavelength. Coupling efficiencies in excess of 90 percent were obtained under best conditions. There was a reduction in coupling efficiency due to the presence of the shield, which was found to be dependent on the proximity of the loop to the antenna and on the Q of the loop. The change in coupling efficiency of the antenna with the shield compared to the antenna without a shield was greater the farther the loop was removed from the antenna and the lower the Q of the loop. In general, the reduction in coupling efficiency due to the shield is probably tolerable, with the advantages of having an electrostatic shield outweighing the disadvantage of a lower power coupling efficiency.     

Model of pressure variation in a vacuum system for volatile liquid evacuation

The behavior of the total and partial pressure in a vacuum system is studied for the case of volatile liquid evacuation. A mathematical model of the process is developed that is based on the joint solution of the balance equations for gas and vapor flows. The influence of the vacuum system parameters and liquid properties on the pressure variation is found. The equilibrium pressure and evacuation time are numerically calculated for different system’s parameters.