HL-2A装置ECRH系统指标介绍

在HL-2A装置上正在开展电子回旋共振加热（ECRH）项目的工程研制，系统具有1MW，68GHz，1s的微波规模。采用弱场侧O模式注入，ECRH的定域加热特性可以用于等离子体加热、电流驱动和分布控制以及改善约束等实验的物理研究。到目前为止，电子回旋共振加热的各项子系统正在设计和研制中，系统的总体物理和工程参数已经初步确定，在此对其作一介绍。     

HL-2A 装置ECRH天线系统的结构设计

HL- 2A 装置电子回旋共振加热的天线系统主要由天线外壳、椭球镜、平面镜、转动机构和推动机构组成。转动机构可以推动平面镜环向、极向转动, 进行不同区域的等离子体的加热和电流驱动。平面镜环向转动的角度范围为0°~ 37°, 极向转动的角度范围为0°~ 15 °。给出了驱动杆与平面镜转动角度之间的关系和对应曲线。介绍了椭球镜的安装和推动机构的结构, 给出了椭球镜的椭球面方程。整个天线系统结构紧凑, 安装和拆卸容易, 调节方便。     

HL-2A装置ECRH传输系统的概念设计

HL-2A装置将建造一个75GHz／1 MW／1s的ECRH系统。本文介绍了由传输线和水平天线构成的传输系统的概念设计(见图1)。详细介绍了系统的主要部件：波导，椭球镜，CVD窗(见图2)和可调节的平面镜。对天线的新设计能使波束极向可调，使得能量能沉积在不同区域。     

HL-2A装置ECRH系统传输效率的测量研究

介绍了HL-2A装置ECRH系统传输效率的测量方法。通过对MOU、回旋管输出窗口及真空密封窗口吸收功率的测量,得到HL-2A电子回旋系统的传输效率为90％左右。提出了除由MOU处测量微波功率外,可以由传输线的其他部位确定功率的方法。     

HL-2A装置ECRH系统的微波功率测量

新研制的微波功率测量系统主要由温度传感器、功率标定电源、电子学处理单元、数据采集和数据处理单元等几部分组成,通过测量EC系统MOU部件冷却水回路进水口和出水口的温度变化,得到MOU吸收的杂模功率。根据回旋管输出功率中的杂模含量比,计算得到回旋管的输出功率。在回旋管调试和ECRH实验期间,測量了4路回旋管的输出功率。从测量结果可知,HL-2A装置ECRH系统可提供大于1.6MW的总输出功率。     

HL-2A装置ECRH系统的新天线设计

Using the principle of quasi-optic, the new antenna of the electron cyclotron resonant heating(ECRH) system on the tokamak HL-2A has been designed. After being focused by the elliptical mirror and reflected by the plane mirror, 4 68GHz/500kW/1s electron cyclotron wave beams would be injected into the tokamak from one Æ350mm port to accomplish heating to the plasma. Based on the propagating theory of the fundamental Gaussian beam, it is gotten that at the centre of the cross section of the tokamak, the power density of each beam is 158MW•m^-2, and the power density radius, which means that the power density is reduced by a factor 1/e² compared to the power density at the centre of the beam, is 31.7mm. On the mirror, due to the focusing and reflecting, the ohmic loss and diffraction loss of the microwave beams are 0.27% and 0.64%, respectively. By the finite element analysis software ANSYS, some thermal analysis of the mirror have been done. The result shows that the highest temperature increase would be only 0.47℃ under 1s pulse load, so there is no need of any cooling.     

HL-2A装置ECRH超导磁体磁场分布测量

测量了HL-2A装置ECRH超导磁体的磁场分布。测量结果析表明,其归一化纵向磁场在磁场中心20mm区域内大于0.992,径向分布在磁场中心平面上浮动小于1.48%,杂散场在贴近超导磁体表面时的最大分量小于50mT,满足实验要求。     

HL-2A装置ECRH高压电源分析计算和模拟仿真

HL-2A装置电子回旋共振加热系统主要由4只68GHz，550kW，脉宽1s，管体接地，阴极电压-55kv，阳极电压25kV，电流25A的回旋管组成。本文介绍的ECRH高压电源是同旋管的主高压电源，它主要用于加速束电流，提供直流输入功率．主高压电源的稳定对有效地提高回旋管的电功率与微波功率的转换效率起着重要的作用。     

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在ECRH高压电源中采用了高压脉冲调制器，大大缩小了电源脉冲上升和下降时间并能提供快速保护。介绍了电子回旋高压电源的主回路结构。计算了电源的前级等效电阻，对电源的动态响应进行了计算分析。运用MATLAB建立模型对电源进行仿真，给出了实验对比结果。     

HL-2A装置ECRH／ECCD天线系统的设计

电子回旋加热和电子回旋驱动（ECRH／ECCD）近年来取得了巨大的进展，如Tore Supra，JT-60U，Heliotron J。与其它的加热和驱动相比，ECRH／ECCD有很多优点。首先，天线可以远离等离子体；其次，ECRH／ECCD的能量可以以功率很集中的高斯束分布注入到等离子体，得到高度集中的定域的能量沉积，使得E-CRH／ECCD成为一种理想的定域的MHD控制手段。     

HL-2A装置ECRH的微波强度分布测量与分析

利用红外热像仪测量微波传播路径上的三个不同距离截平面上的微波强度分布,计算出辐射图的一阶及二阶矩并重建相位信息,可以确定微波波束的强度分布和准直度。使用该方法对两套ECRH系统传输线进行了定量的分析,获得了微波强度分布均为高斯分布、7m 3^#传输线的微波束线准直度为0.05°、6m 4^#传输线微波束线准直度为0.14°的结果。     

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应用准光学原理设计了HL-2A装置电子回旋共振加热(ECRH)系统新的集束天线,该天线能使4束68GHz/500kW/1s电子回旋波通过椭球镜聚焦和平面镜的反射,从一个直径350mm装置窗口同时注入托卡马克,对等离子体实现加热。根据基模高斯束的传播原理得出,在装置环向横截面中心处单条波束的功率密度为158MW•m-2,功率密度降为中心密度的1/e2的半径为31.7mm,微波束经过镜面聚焦和反射产生的欧姆损失和衍射损失分别为0.27%和0.64%。利用有限元分析软件Ansys对镜面进行热分析得到,在1s脉冲载荷下最大镜面温升仅为0.47℃,镜面可以自然冷却。     

The Analysis and Calculation on ECRH Anode Circuit on the HL-2A Tokamak

In the last year, ECRH system has been built in the HL-2A and the testing of gyrotron is also finished. In the project testing, one of the problems is current-peak occurring in the anode circuit of gyrotron. The current-peak is much larger than that of the value set in protection circuit. The frequent current-peak frequently occurring in the rising of anode-voltage often caused the protection circuit to mistaken trigger. The mistaken triggering often halted the normal gyrotron-testing. A set of equations of anode circuit are derived for analysis the phenomena of the current-peak. The calculation based on the deduced formula shows that value of the current-peak strongly depends on the inductance L, capacitance C and the ramp-time of anode voltage in the anode circuit. The conductance L and capacitance C are the characteristic inductance and capacitance of the cable that is used for anode HV power supply. The numerical calculation is exactly consistent with waveform of the current peak recorded by oscillograph, that means the derived formula are correct. In order to decrease the value of the current-peak, we should decrease capacitance C, and increase inductance L and ramp-time of anode voltage.     

HL-2A装置上ECRH实验的初步结果和电子热输运分析

电子回旋共振加热（ECRH）是托卡马克等离子体一种最常用的辅助加热手段，也是进行等离子体电子热输运和约束性能研究的一种有效手段。本文介绍了HL-2A装置上ECRH实验的初步结果，分析了在ECRH实验期间的电子热输运特征和约束情况。     

HL-2A装置ECRH系统回旋管超导磁体的调试

为了在HL-2A装置上开展电子回旋共振加热实验研究，我院从俄罗斯GYCOM公司引进了两套4mm回旋管。它们均配有一个超导磁体系统，提供回旋管所需的磁场位形。回旋管中的磁场不仅仅起聚焦作用，更重要的是形成回旋电子束必不可少的，其作用为：（1）电子要产生回旋运动必须要有磁场；（2）回旋电子束要获得足够强的横向能量必须有足够强的绝热压缩量。通过调试测量了磁体磁场分布，确定了磁体工作电流及回旋管工作频率。     

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介绍了HL-2A装置ECRH系统传输效率的测量方法。通过对MOU、回旋管输出窗口及真空密封窗口吸收功率的测量,得到HL-2A电子回旋系统的传输效率为90％左右。提出了除由MOU处测量微波功率外,可以由传输线的其他部位确定功率的方法。     

The ECRH Transmission System for HL-2A Tokamak

Electron cyclotron resonance heating and electron cyclotron current drive （ ECRH/ECCD ） have been developed significantly in recent years in many devices such as Tore Supra, JT-60U, Heliotron J. It has many advantages over other means of heating and current drive. The EC power can be injected as narrow gaussian beams, giving rise to so highly localized power deposition as to make ECRH an ideal candidate for local MHD control.     

Superconducting Magnet of the Gyrotron for HL-2A ECRH System

In order to carry on ECRH experiments and research on HL-2A tokamak, two sets of 4 mm gyrotrons were imported from GYCOM. Each of them has a superconducting magnet system to offer a required magnetic field configuration. In gyrotron, a strong magnetic field is necessary for electron beam to satisfy the electron cyclotron resonance condition and to excite one the eigemodes in the cavity. Its functions are： （I） to make electrons gyrate, （ 2 ） to offer enough adiabatic compression value to make electrons acquire strong transverse energy. During the period of adjustment, magnetic field distribution was measured. Meanwhile, operating current of superconducting magnet and operating frequency of gyrotron were determined.