HT-7装置上充气对低杂波耦合影响的实验及分析

在低杂波（LHW）天线端口充D₂和CD₄,发现LHW的耦合效果能得到明显改善,充气后LHW的反射系数基本降为6%左右。不同窗口充气对波的耦合和等离子体密度的影响不同,其原因是改善耦合的关键是提高刮削层（SOL）内等离子体的密度。D₂与CH₄对LHW耦合影响的实验结果表明：D₂对LHW的耦合效果影响略好于CH₄,但D₂对等离子体密度的影响明显高于CH₄,原因是D₂对电子密度的贡献更大。     

EAST 2MW/2450MHz低杂波电流驱动系统综述

为了研究全超导托卡马克稳态高参数等离子体性能,2008年在EIAST装置上研制并成功建成了-套最大能传输2兆瓦,工作频率是2450MHz的低混杂波电流驱动系统.该系统主要由20个速调管放大器、4套高压源、20路每路30～40米长的WR430标准矩形波导传输线和多结波导天线阵列组成.辐射波谱的控制是通过子波导内的固定移相器和微波前级的数字可调移相器两种移相手段来实现.在低杂波系统的辅助下成功实现了:驱动中心密度为1～2×1013cm-3下150～500kA的等离子体,全波驱动250kA电流达23s和低杂波辅助启动实验,所有的这些实验都证明了整个低杂波系统的稳定和可靠性.详细描述了整个系统的构成和初步的实验结果.     

多结波导阵天线及其在低杂波电流驱动实验中的应用

研制了一种新型的低杂波耦合结构——多结波导阵天线。在这种天线中,功率分配是通过矩形波导的E面结来实现的,相邻波导间的相位差则利用在子波导中插入不同长度的聚四氟乙烯介质块来获得。使用这种多结波导阵天线,我们在HT—6M托卡马克装置上成功地开展了低杂波电流驱动实验,取得了ηCD=0.55(1O~(13)cm~(-3)·m·kA/kW)的好结果,并在很低的微波功率水平下观察到了对MHD行为的影响。     

EAST4.6GHz/4MW低杂波电流驱动系统隔直器优化设计

为了研究全超导托卡马克稳态高参数等离子体性能,2008年在EAST托卡马克装置上研制并成功建成了一套能最大传输2兆瓦,工作频率是2450MHz的低混杂波电流驱动系统,要实现低杂波长时间地维持等离子体电流,还需要对低杂波系统的输出功率大小及运行时间长度提出更高要求,拟研制一套波源输出功率4 MW,中心频率4.6GHz,波谱范围为1.7< N_(//)< 2.5,运行脉冲宽度0～1000秒低杂波电流驱动系统.在EAST4.6GHz/4MW低杂波电流驱动系统中,因为速调管放大器和低杂波天线有共同的接地点,速调管放大器电源为负高压,有接地点,低杂波天线有接地点,并且和EAST托卡马克相连,在系统中要求不能有两个接地点,所以要通过隔直器来隔断托卡马克和速调管之间的的直流通路.论文详细介绍了隔直器的原理和设计过程,在以4.6GHz为中心频率,150MHz的频带范围内,隔直器各个端口微波性能良好.     

HL-2A装置LHCD的运行区域与驱动电流分布控制

本文利用低杂波电流驱动(LHCD)的理论和实验结果,讨论了电流驱动效率和电流分布控制与等离子体参量及入射波谱的关系,强调了波传播在确定功率沉积分布区域中的作用,并讨论了控制电流密度分布的方法,探索在HL-2A装置上实现中心负磁剪切位形的可能性。 早在80年代,实验和理论研究就奠定了低杂波电流驱动(LHCD)的物理基础。在理论上,利用射线追踪技术和Fokker-Planck方程的不     

HT-7中长时间低漂移模拟积分器的研制

电磁测量是托卡马克装置中最基本的诊断方法,通常利用磁感应原理来测量HT-7装置内部磁场和磁通,因此需要用积分器对磁测量的输出信号进行积分。讨论了单运放模拟积分器的特点,提出了利用实时积分漂移补偿的方法设计新型积分器,解决了积分过程中积分器本身的等效输入偏移量、温度漂移及地噪声等带来的积分误差。给出了系统原理和设计框图,并在HT-7超导托卡马克的实验中,验证了该积分器能够满足等离子体长时间放电对积分器在积分精度和噪声精度上的要求。     

HT-7U NbTi 管内电缆导体瞬态稳定性的实验研究与分析

在SULTAN 测试设备上进行了含分离铜股线CICC瞬态稳定性的实验研究,应用脉冲场对样品的脉冲场区域(390 mm)进行感应加热,发现设计的含分离铜股线CICC能够经受住很大的瞬态磁扰动,分析了这个现象的原因,并就股线上的电阻层对稳定性的影响进行了分析,对4个CICC导体的稳定性差异进行分析和稳定性裕度的理论计算,由理论计算值和实验测量值进行比较分析,为HT-7U纵场和极向场NbTi CICC的选择提供实验依据.     

低压低功率条件下两相自然循环特性试验研究

相比于陆基核电厂,船用核动力装置的非能动安全系统运行压力较低,运行功率变化频繁,在两相自然循环条件下,非能动安全系统内的流动更加复杂多变。为了研究两相自然循环在低压、低功率条件下的循环特性,基于比例分析方法搭建了两相自然循环的原理试验台架,研究了低压条件下功率和初始液位高度对自然循环特性的影响。结果表明,在低压条件下,系统稳定运行后的压力、流量等均受初始液位高度和功率的影响。当功率为50 kW时,初始液位越高,系统稳定后的压力越大,但是流量相差较小;初始液位一定时,功率在40%满功率～100%满功率内,随着功率的增大,系统稳定后的压力也逐渐增大。这为试验台架后续两相自然循环的研究提供了方向,也为船用核动力装置非能动安全系统研究提供了参考。     

用于托卡马克低混杂波电流驱动的多结波导阵天线

多结波导阵天线是为在中国科学院等离子体物理研究所的ＨＴ－６Ｂ、核工业西南物理研究院的ＨＬ－１和ＨＬ－１Ｍ托卡马克（Ｔｏｋａｍａｋ）装置上进行低混杂波电流驱动（ＬＨＣＤ）实验用的，已取得了一系列有价值的物理数据。文章着重介绍这类天线的物理和结构特性以及制造中的技术难点，并简要介绍用１×８和２×１２路多结阵天线分别在ＨＴ－６Ｂ、ＨＬ－１Ｍ托卡马克上进行的ＬＨＣＤ的实验结果。     

Enhanced Lower Hybrid Current Drive Experiments on HT-7 Tokamak

Effective Lower Hybrid Current Driving (LHCD) and improved confinement experiments in higher plasma parameters (Ip > 200 kA, ne > 2 ×1013 cm-3, Te≥ 1 keV) have been curried out in optimized LH wave spectrum and plasma parameters in HT - 7 superconducting tokamak. The dependence of current driving efficiency on LH power spectrum, plasma density ne and toroidal magnetic field BT has been obtained under optimal conditions. A good CD efficiency was obtained at higher plasma current and higher electron density. The improvement of the energy confinement time is accompanied with the increase in line averaged electron density, and in ion and electron temperatures. The highest current driving efficiency reached ηCD = IpneR/PRF≈1.05×1019 Am-2/W. Wave-plasma coupling was sustained in a good state and the reflective coefficient was less than 5%. The experiments have also demonstrated the ability of LH wave in the start-up and ramp-up of the plasma current. The measurement of the temporal distribution of plasma     

Impact of Toroidal Effect on Lower Hybrid Current Drive in Tokamak

The main topics concerning lower hybrid wave heating （LHH） and lower hybrid current drive （LHCD） in tokamak systems are presented. The inherent properties of tokamak systems give the ‘gap＇ filling on Brambilla＇s spectrum, which are conducive to LHCD, but, on the other hand, induce a consumption of wave energy by the trapped electrons, which reduce the current drive efficiency. The methods for the enhancement of the current drive efficiency may be derived from detailed analyses by drawing upon the ray tracing technology on toroidal geometry and the Fokker-Planck theory on velocity space.     

LHCD Properties with a New Lower Hybrid Wave Antenna on HT-7 Tokamak

1 IntroductionLower hybrid current drive (LHCD) has become aneffective method to maintain plasma current in a toka-mak. Plenty of experimental results on the HT-7 toka-mak also show that LHCD is an important auxiliarymeans to achieve steady state operation of the toka-mak and to obtain plasmas with improved confine-ments [1~4]. In the experiments, lower hybrid wave(LHW) with a frequency of 2.45 GHz is launched intothe plasma by an LHW antenna. Since the power spec-trum of the launched …     

Experimental Investigation of Lower Hybrid Wave Coupling in HT-7

Experiments on lower hybrid wave(LHW)coupling were investigated in the HT-7 tokamak.Good coupling of LHW plasma has been demonstrated at different conditions in the HT-7 tokamak.Relevant results have proved that LHW-plasma coupling is affected by the phase difference between adjacent waveguides.Furthermore,the edge density around the grill and relevant coupling can be adjusted by changing the plasma line average density or the gap value between the LH grill and the last closed flux surfaces(LCFS).It is found that the coupling of LHWs becomes poor when the edge density around the LH grill is large enough in the HT-7tokamak,and that coupling remains good with a proper edge density.With increasing LHW power,it is also found that the reflection coefficients(RCs)increase due to non-linear effects under conditions of low edge recycling,but can decrease under high edge recycling.The edge density depends mainly on the competition between the ponderomotive force(PMF)and the edge recycling intensity in the HT-7 tokamak.     

Analysis of Charge-Exchange Spectrum during Lower Hybrid Current Drive on HT-7 Tokamak

1. IntroductionUsually the ion temperature is determined in magnetically confined plasmas by measurements of theenergy distribution of the fast neutral particles.The tokamak experiments have been devoted to thestudy of high-power additional heating. Accordingto the theory and many tokamak experimental results, plasmas that are additionally heated usuallyhave non-Maxwellian high-energy component (highenergy tail) with a concomitant bulk ion heating bycollision energy exchange between the ion ta…     

Experiment and Operation of a LHCD—35kV／2.8MW／1000s High—Voltage Power Supply on HT—7 Tokamak

A-35kV/2.8MW/1000s high-voltage power supply(HVPS) for HT-7 superconducting tokamak has been built successfully.The HVPS is scheduled to run on a 2.45 GHz/1MW lower hybrid current drive(LHCD)^[1] system of HT-7 superoonducting tokamak before the set-up of HT-7 superconducting tokamak in 2003.The HVPS has a series of advantages such as good steady and dynamic response,logical computer program controlling the HVPS without and fault,operationa panel and experimental board for data acquisition.which both are grounded distinctively in a normative way to protec the main body of HVPS along with its attached equipments from dangers.Electric power cables and other control cables are disposed reasonably,to prevent singals from magnetic interference and ensure the precision of signal transfer.This paper involves the experiment and operation of a 35kV/2.8 MW/1000s HVPS^[2] for 2.45 GHz/1 MW LHCD system.The reliability and feasibility of the HVPS has been demonstrated in comparison with experimental results of original design and simulation data.     

Investigation of the Energy Confinement in Ohmic and LHCD Plasmas in HT-7

Investigation of the energy confinement in ohmic and lower hybrid current drive （LHCD） plasmas in HT-7 has been performed. In ohmic discharges at low densities the global energy confinement time rE increases almost linearly with the density, saturates at a critical density （2.5×10^13/cm^3 for HT-7） and is nearly constant at higher densities. The energy confinement time is in good agreement with the Neo-Alcator scaling law at different densities and currents. In the LHCD plasmas the global energy confinement time similar to that of the L-mode discharges has been observed to be in good agreement with the low confinement mode （L mode） scaling law of ITER89-P in higher electron density and plasma current.     

Analysis of Charge Exchange Spectrum During Lower Hybrid Current Drive on HT-7 Tokamak

This paper presents the experimental results by charge-exchange fast neutral particle measurements with neutral particle energy analyzer (NPA) in lower hybrid current drive (LHCD) experiments, which firstly show ion heating of LHCD on HT-7 superconducting tokamak. The LHCD experiments on HT-7 tokamak were carried out with the following paramenters: B_t=1.8 T, I_p=110～150 kA, n_e=(0.8～2)×10~(13)cm~(-3). The lower hybrid wave (LHW) had a pulse duration of 360ms and power of about 300 kW with an peak of parallel refractive index of N_〃=2.9.