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HL-2A装置MHD不稳定性实时预测破裂系统采用了一种简单有效的方法来预测MHD不稳定性导致的等离子体大破裂。利用Mirnov线圈探测MHD信号,根据信号的振幅或频率特点设定计算方法,来预测等离子体破裂先兆,然后用激光吹气注入杂质来缓解等离子体破裂。研究结果表明,该系统能够实时预测破裂先兆,按量注入杂质后,可达到破裂缓解目的。     

Study of runaway electron behaviour during electron cyclotron resonance heating in the HL-2A Tokamak

During the current flat-top phase of electron cyclotron resonance heating discharges in the HL-2A Tokamak, the behaviour of runaway electrons has been studied by means of hard x-ray detectors and neutron diagnostics. During electron cyclotron resonance heating, it can be found that both hard x-ray radiation intensity and neutron emission flux fall rapidly to a very low level, which suggests that runaway electrons have been suppressed by electron cyclotron resonance heating. From the set of discharges studied in the present experiments, it has also been observed that the efficiency of runaway suppression by electron cyclotron resonance heating was apparently affected by two factors: electron cyclotron resonance heating power and duration. These results have been analysed by using a test particle model. The decrease of the toroidal electric field due to electron cyclotron resonance heating results in a rapid fall in the runaway electron energy that may lead to a suppression of runaway electrons. During electron cyclotron resonance heating with different powers and durations, the runaway electrons will experience different slowing down processes. These different decay processes are the major cause for influencing the efficiency of runaway suppression. This result is related to the safe operation of the Tokamak and may bring an effective control of runaway electrons.     

Density Fluctuation Measurements Using FIR Interferometer on HL-2A Tokamak

Density fluctuations were first measured in the core region of HL-2A tokamak plasma using a newly developed multi-channel FIR interferometer system. In divertor ohmic discharges, we measured the radial density fluctuation levels of 5%, which increase to 10-20% during the appearance of MHD activity. Most of the power density in the density fluctuation spectrum is directly associated with m = 2 tearing modes. The fluctuation levels reduce to 1/3 and plasma confinement is improved during off-axis electron-cyclotron-resonance heating （ECRH）.     

双棱镜干涉4种实验方法的研究与探讨

从理论和实验两方面对双棱镜干涉实验常用的4种实验方法进行了分析和比较,指出了各自的优缺点和不同之处,得出了双棱镜干涉测波长的最佳实验方案,并提出了2条提高测量精度的改进意见.     

RMF理论中Zr同位素链壳结构的形变依赖性

基于球形与轴对称形变的相对论平均场（Relativistic Mean Field, 简称RMF）理论模型, 分别计算了Zr同位素链的基态总能量, 并根据其差值提取了形变修正能后发现, Zr同位素链丰中子区的核具有大的长椭形变, 对应的形变修正能可达到10 MeV。 利用RMF理论计算的基态能量, 在扣除液滴模型计算的结合能后, 得到了Zr同位素链的壳修正能。 通过对壳修正能的分析后发现, 形变使N=50壳效应显著减弱。 特别是在丰中子区, 大形变导致了N=50壳结构的消失。 The total binding energy of nuclei for Zr isotopic chain is calculated by the spherical and axial deformed relativistic mean field(RMF) theory respectively, and the energy contribution due to the deformation(i.e., deformation correction energy) is extracted. It is found that the neutron rich nuclei in the isotopic chain have large prolate deformation, and corresponding deformation correction energy can be up to 10 MeV. The shell correction energy is obtained by the difference between the binding energies calculated by the liquid model and those by the RMF calculations. Detailed analysis indicates that the deformation weakens the shell effect of N=50 remarkably. Especially for the neutron rich nuclei, large deformation leads to disappearance of the N=50 shell structure.     

Simulation of radiation losses using non-coronal model on HL-2A

In this paper, the radiation losses of impurity on HL-2A have been simulated by assuming the profiles electron temperature and density and solving ionization rate equation under conditions of non-coronal radiation. The time required for an impurity species to establish equilibrium is proved to be sensitively dependent on the plasma electron temperature, and it is strongly correlated with the ionization state distribution during equilibrium establishment of impurity species. It is found from simulation results that the residence parameter plays an important role in the enhancement of radiation losses of plasma.     

線代数学的基本概念(續)

§2.欧几里得空間 8.欧几里得空間的定义,前面我們已經看到,在一个線性空間中可以定义平面、直線、平行和相交的概念等,不过决不能以線性空間的术語定义像向量的長、向量之間的角这样的基本几何概念,我們將根据用公理法定义的数量乘积的概念来引入这些概念*)。定义7.如果線性空間R的每一对向量x,y与某一实数(x,y)对应,而且这一对应具有下面的性質:     

在中學數學課程中的邏輯概要

在高年級的數學教學中,必然要面臨這樣的一個時刻,這時為了使學生能自覺地與深刻地掌握今後的課程,應當本質上依據某些邏輯概要的知識,不過在以前的各年級中,學生不可能獲得必要的知識,所以在一定的教學階段上就產生了迫切的需要:給予學生一些有系統的、嚴格地敘述的、最低限度的數學的邏輯概要。我的個人經驗以及曾與我討論過這一問題的教師們的經驗證明,在邏輯學的領域內走馬觀花地流覽,不可能給上面所提的問題以充分全面的解答,所以我用一個定名為“數學命題和證明方法”的專門的課題給予學生們這些最低限度的邏輯知識。根據進行這一課題的四年工作經驗,產生了它的具體計畫,這一計畫我將在下面提出以供大家討論。     

飞秒实时单次相敏自相关技术研究

本文介绍飞秒实时单次相敏自相关技术的测量原理。给出完全探测CPM Nd:YAG皮秒光脉冲复电场的实验结果及讨论。     

HgCdTe-IRFPA成像器件光谱响应率标定方法比较与误差分析

红外焦平面成像器件的光谱响应率是天基红外遥感的基本物理指标。为了准确应用该项参数去除器件在制造工艺中的不均匀性对产品质量的影响，必须在系统使用之前对其重新标定，获取真实值。总结了目前较为普遍的IRPFA产品光谱响应率标定方法，通过比较选择标准代替法对产品进行标定。根据所得到测量数据，分析了其可能存在的误差，总结了在对IRPFA产品进行标定时应注意的问题。同时提出了一种调整积分时间的方法，以弥补有些波段标定黑体辐射功率过低带来误差过大的缺陷。