Investigation on the multi-hole directional coupler for power measurement of the J-TEXT ECRH system

Power measurement is necessary for an electron cyclotron resonance heating(ECRH)system.The directional coupler method has been put forward to monitor high-power microwave from gyrotrons in real time.A multi-hole directional coupler has been designed and manufactured for the 105 GHz/500 kW ECRH system on the J-TEXT tokamak.During the design process,we established the relationships between hole parameters and coupling characteristics based on the multi-hole coupling method and small-hole coupling theory.High-power tests have been carried out.The results indicated the reasonability of the theoretical design and practicality of the fabricated directional coupler.Sources of test errors have been discussed in detail,and the influences of spurious modes on the directional couplers have been emphatically analyzed.

Development and Preliminary Commissioning Results of a Long Pulse 140 GHz ECRH System on EAST Tokamak(Invited)

A long pulse electron cyclotron resonance heating（ECRH）system has been developed to meet the requirements of steady-state operation for the EAST superconducting tokamak,and the first EC wave was successfully injected into plasma during the 2015 spring campaign.The system is mainly composed of four 140 GHz gyrotron systems,4 ITER-Like transmission lines,4 independent channel launchers and corresponding power supplies,a water cooling,control ＆inter-lock system etc.Each gyrotron is expected to deliver a maximum power of 1 MW and be operated at 100-1000 s pulse lengths.The No.1 and No.2 gyrotron systems have been installed.In the initial commissioning,a series of parameters of 1 MW 1 s,900 k W 10 s,800 k W 95 s and650 k W 753 s have been demonstrated successfully on the No.1 gyrotron system based on calorimetric dummy load measurements.Significant plasma heating and MHD instability suppression effects were observed in EAST experiments.In addition,high confinement（H-mode）discharges triggered by ECRH were obtained.

Recent progress of the ECRH system and initial experimental results on the J-TEXT tokamak

In order to broaden the range of the plasma parameters and provide experimental conditions for physical research into high-performance plasma,the development of the electron cyclotron resonance heating(ECRH) system for the J-TEXT tokamak was initiated in 2017.For the first stage,the ECRH system operated successfully with one 105 GHz/500 kW/1 s gyrotron in 2019.More than 400 kW electron cyclotron(EC) wave power has been injected into the plasma successfully,raising the core electron temperature to 1.5 keV.In 2022,another 105 GHz/500 kW/1 s gyrotron completed commissioning tests which signifies that the ECRH system could generate an EC wave power of 1 MW in total.Under the support of the ECRH system,various physical experiments have been carried out on J-TEXT.The electron thermal transport in ECRH plasmas has been investigated.When ECRH is turned on,the electron thermal diffusivity significantly increases.The runaway current is elevated when a disruption occurs during ECRH heating.When the injected EC wave power is 400 kW,the conversion efficiency of runaway current increases from 35% to 75%.Fast electron behavior is observed in electron cyclotron current drive(ECCD) plasma by the fast electron bremsstrahlung diagnostic(FEB).The increase in the FEB intensity implies that ECCD could generate fast electrons.A successful startup with a 200 kW ECW is achieved.With the upgrade of the ECRH system,the J-TEXT operational range could be expanded and further relevant research could be conducted.

Calorimetric power measurements in the EAST ECRH system

In this paper, the measurement method of calorimetric power for an electron cyclotron resonance heating（ECRH） system for EAST is presented. This method requires measurements of the water flow through the cooling circuits and the input and output water temperatures in each cooling circuit. Usually, the inlet water temperature stability is controlled to obtain more accurate results.The influence of the inlet water temperature change on the measurement results is analyzed for the first time in this paper. Also, a novel temperature calibration method is proposed. This kind of calibration method is accurate and effective, and can be easily implemented.

Development of a 140 GHz Steerable Launcher for the HL-2A ECRH System

A new electron cyclotron resonance launcher system has been designed and installed on heating and current drive （ECRH/ECCD） the HL-2A tokamak to inject four beams and enable continuous millimeter-wave beam scanning independently in the toroidal and poloidal direc- tions for ECRH/ECCD experiments. The launcher is connected to four mm-wave lines capable of transmitting high power up to 3 MW with two 1 MW/140 GHz/3 s and two 0.5 MW/68 GHz/1 s beams. Based on ray tracing simulation using the TORAY-GA code, tile scanning range of wave beams is -15~~15~ in the toroidal direction and 0~~10~ in the poloidal one for 140 GHz beams, which could cover half of the cross section of plasmas and can satisfy the requirements of advanced physical experiments. The beam radii in the plasma is 17.1 mm and 20 mm for the two 140 GHz beams and 29.5 nnn for the two 68 GHz beams, respectively, allowing a very high localization of the absorbed power. The performance of the steering system was proven to be reliable and the linearity is perfect between the displacement of drive shaft and rotate angle of mirror. Addition- ally the injection performance of the wave beams was optinfized by simultaneously setting the injection angle and the polarization to realize desirable pure O- or X-mode injection.

The anode power supply for the ECRH system on the J-TEXT tokamak

The electron cyclotron resonance heating （ECRH） system with a 60 GHz/200 kW/0.5 s gyrotron donated by the Culham Science Center is being developed on the J-TEXT tokamak for plasma heating, current drive and MHD studies. Simultaneously, an anode power supply （APS） has been rebuilt and tested for the output power control of the gyrotron, of which the input voltage is derived from an 80 kV negative cathode power supply. The control strategy by controlling the grid voltage of the tetrode TH5186 is applied to obtain an accurate anode climbing voltage, of which the output voltage can be obtained from 0-30 kV with respect to the cathode power supply. The characteristics of the APS, including control, protection, modulation, and output waveform, were tested with a 100 kV/60 A negative cathode power supply, a dummy load and the ECRH control system. results indicate that the APS can meet the requirements of the ECRH system on J-TEXT.

The Introduction to the ECRH System of the HL-2A Tokamak

The 1 MW/68 GHz/1 s ECRH system of HL-2A device is being designed or fabricated. The O mode wave beams are injected into plasma from low field side of the HL-2A tokomak. Because the EC wave can heat plasma locally, it is a very versatile scheme which has been employed to heating, current drive, profile control, confinement improvement. Up to now, the basic physical and engineering parameters of the whole system have been fixed and the subsystems are being designed or fabricated.

The Design of an Elliptical Reflector in the Gaussian-like Antenna Used in HT-7 ECRH System

The structure of the antenna which will be used in HT-7 tokamak electron cyclotron resonance heating (ECRH) experiment and the design of its key component (the elliptical reflector) were introduced. A quasi-Gaussian TE11 wave sent from the TE01-TE11 mode converter was reflected by two mirrors from the waveguide aperture to the plasma center area. One of the two mirrors is a plane mirror and the other is an elliptical mirror. In this process, the wave beam will be converged by the two reflecting mirrors and the emissive direction of the wave is also controlled by them. As requested physically for ECRH experiment, the arrangement of the two mirrors can ensure the wave to be launched from the low-field side of the tour.

Design ofthe ECRH/ECCD Launcher System for HL-2A Tokamak

An ECRH/ECCD system with two 68GHz/500kW/1S gyrotrons will be built up in HL-2A tokamak. The location of the Gaussian beam waist is 580 mm away from the center of the plasmas and the beam radius is 37 mm at the center of the plasmas. Compared to the minor plasma radius （420 mm）, it is small enough for localized control. The launcher system covers a wide toroidal and poloidal steering range by the two steering plane mirrors. Therefore it is possible to explore the on- and off-axis heating over half of the plasma minor cross section and the co-current drive.

The Design of PSM-Based ECRH Power Supply Control System

Electron cyclotron resonance heating (ECRH) system is one of the most important Tokamak auxiliary heating methods. However, there are growing demands for ECRH system as the physical experiments progress which meanwhile adds the difficulty of designing and building the control system of its power source. In this paper, the method of designing a control system based on Single Chip Microcomputer (SCM) and Field Programmable Gate Array (FPGA) is introduced according to its main requirements. The experimental results show that the control system in this paper achieves the conversion of different working modes, gets exact timing, and realizes the failure protection in 10us thus can be used in the ECRH system.

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.

Design of the ECRH Transmission System for HL-2A Tokamak

HL-2A tokamak will be equipped with a 75 GHz/1 MW/1 s ECRH system. The paper describes the design of the transmission system (Fig. 1), which is made up with a transmission line, an equatorial launcher. The paper describes the design of main components of the system such as, waveguides, ellipsoidal surface mirrors, a chemical vapor (CVD) diamond window, a steering mirror.

CFETR ECRH系统发射天线的初步结构设计与分析

电子回旋共振加热(ECRH)是中国聚变工程实验堆(CFETR)实现科学目标必不可少的辅助加热和电流驱动方式。发射天线是电子回旋共振加热系统的核心部件之一。为获得等离子体最佳的电流驱动效率,从发射天线的总体方案、波束的传输、波束的汇聚与发射、中子屏蔽、维护方案等方面对ECRH系统顶部发射天线的初步结构进行了设计。ECCD发射天线通过多波束汇聚方式,在CFETR装置紧凑的顶部颈管内,实现了2组9波束微波功率注入至等离子体共振层。发射天线采用颈管插塞式结构设计,有利于中子屏蔽设计和遥操作维护。通过流-热-固耦合仿真分析,为天线发射镜设计了有效的主动冷却方案。本文的分析和设计,为ECRH发射天线进一步的详细工程设计奠定了基础。

The Control System of ECRH HV Power Supply

In order to satisfy the requirement of ECRH for power supply, pulse high voltage （ HV ） power supply has been developed. The main parameters of the power are： output voltage -55 kV, output current 25 -2 A, stability ±0.5%, pulse duration 1 s, the leading edge and lagging edge of the pulse is about 40 μs and so on. On the other hand, the system should have preferable protective capability. In this paper, the hardware and principle of the power supply, hardware, software and arithmetic method of the control system are presented.

ECRH负高压脉冲电源控制系统的研究与设计

负高压脉冲电源是ECRH系统最重要的组成部分之一,文中分析了ECRH负高压脉冲电源的组成及工作原理。根据控制要求设计出系统各环节的工作电路,设计出带有前馈的PI调节器,利用MATLAB仿真确定出调节器参数,并根据MATLAB仿真结果进行实验,实验表明,系统具有良好的控制特性。

ECRH负高压脉冲电源系统的电磁兼容性研究

负高压脉冲电源是ECRH系统最重要的组成部分之一 ,其工作的安全与可靠性直接影响整个系统运行。分析了空间电磁干扰的基本理论 ,针对空间电磁干扰与其他干扰源 ,从系统的安全防护、信号传输、制作工艺等方面 ,提出了几种抗干扰措施。仿真与实验表明 ,提出的几种抗干扰措施具有较明显的抑制干扰的作用。

HL-2A装置ECRH高压电源分析计算与仿真

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,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。

ECRH负高压电源的反馈控制

介绍一种利用大功率四极调整管的调整特性进行串联反馈调节 ,在反馈环节中采用新型带预置值的积分器的高精度的负高压电源。解决了ECRH系统所要求的电压 - 80kV、脉宽10～ 10 0ms、电压稳定度为 99 7%的负高压电源的关键技术问题 ,并通过PSPICE软件仿真 。

HL-1M装置ECRH系统的研制与实验

在HL 1M装置上研制了一套75GHz、500kW/50ms的大型电子回旋共振加热系统,设计了准光学传输系统和顶部、水平两套天线,对系统进行了调试,获得了最佳的系统参数和运行条件,并开展了各种O模和X模实验。在单管250kW的基波O模的实验中,获得电子温度提高40%,电流位形负剪切分布以及鱼骨模不稳定性研究等重要的物理实验结果。