用电子迴旋共振加热抑制托卡马克中的撕裂模

利用电子迴旋共振加热的定域性,改善等离子体电流分布,从而改善撕裂模的稳定条件,只要电子迴旋共振加热的吸收区能覆盖住撕裂模的共振层,就有很好的稳定效应;而不一定要求电子迴旋共振面与撕裂模的共振面重合,在迴旋加热期间,撕裂模被有效地抑制住。 关键词：     

能带理论的进展

引言一、能带的形成 1.周期性势场中电子的波函数 2.电子的加速度与速度二、能带计算的主要方法 1.紧束缚法 2.原胞法 3.正交化平面波法三、和能带结构有关的物理性质 1.回旋共振 a.半导体的迴旋共振 b.金属的迴旋共振 2.电流磁效应 a.n型锗和硅 b.p型锗和硅 3.磁化率 a.晶体中电子的磁化率 b.半导体的磁化率 c.底哈斯,凡阿尔芬效应 4.反常的趋肤效应参考文献     

CT-6B托卡马克微波预电离实验

用迴旋管产生的大功率微波在电子迴旋频率的基频及二次谐波频率进行了托卡马克放电的预电离实验。实验证明,这种预电离方法比一般的预电离方法的击穿气压低,击穿电压及放电初期所耗费的变压器磁通也低得多。基频共振较二次谐波共振的效果好。 关键词：     

托卡马克中等离子体频率附近的增强辐射现象

实验提出托卡马克中的等离子体频率附近的增强辐射现象与高能逃逸电子有关,但是辐射的机制尚未完全弄清。本文讨论了两种可能的机制。一种是诱发辐射,这是来自逃逸电子与波的反常迴旋共振。另一种是自发辐射,主要来自契仑柯夫共振。前者要求逃逸电子的能量比后者为大,因此,自发辐射理论更引人注意。在很宽的参数变化范围内对辐射率作了数值计算。对于等离子体频率大于迴旋频率的情况也作了讨论。 关键词：     

电子迴旋激射不稳定性

本文分析了下述情况下的电子迴旋波的激射不稳定性:当相对性的单能高能电子斜向注入具有背景等离子体的磁场区域内,并且在电子等离子体频率与电子迴旋频率可以比拟时,考虑了背景等离子体密度远大于单能的高能电子的密度,以及与前者相反的两种情况。当单能的高能电子具有弱相对论性效应时,在电子迴旋频率的基频和二次谐波附近,分别有ο模和χ模的不稳定性存在。文中计算了这两种模的增长率,并作了讨论。 关键词：     

高电荷态离子N6+与He原子碰撞激发过程的实验研究

利用电子迴旋共振(ECR)多电荷离子源产生的高电荷态离子束和LHT-30VUV真空紫外单色仪,对N⁶⁺与He碰撞激发过程进行研究,观察到三种碰撞激发过程:(1)单电子俘获;(2)双电子俘获;(3)入射离子直接激发过程。 关键词：     

铁磁金属的表面阻抗与自旋波共振

本文计算了铁磁金属在平行磁场中的表面阻抗。计算中考虑了交换作用所引起的磁化率空间色散及趋肤效应的反常性。分别讨论了磁矩的两种边界条件m=0和(?m)/(?n)=0。同时研究了导电电子在表面散射性质的影响。利用Азбель-Канер在迴旋共振理论中的方法,计算了考虑电导率旋磁性条件下的表面阻抗。     

电子迥旋加热等离子体及热电子环特性的实验研究

在简单磁镜MM-2中,采用15GHZ大功率迴旋管进行了电子迴旋共振加热(ECRH)实验。结果表明,随充气压强的提高,预电离时间迅速变短。在高气压“C-模式”运行区,等离子体径向密度分布呈马鞍形。在迴旋管输出30kW功率的条件下,适于建立热电子环的气体压力窗为(0.4—1.2)×10^-5Torr。利用一个可移动Laugmuir探针配合反磁测量的简便方法,在中心场为2.95kG时,确定了电子环半径为7cm,环厚约4cm,环的轴向边界由z=±10cm一直延伸到z=±20cm。热电子温度为140—170keV,热电环平均β值为(4—5)％。观测到了由热电子环不稳定性引起的迸发式径向电子逃逸,并同时发生反磁信号跌落。     

电子束注入简单磁镜中被电子迴旋共振加热捕获的实验研究

在简单磁镜MM-2中,在采用15GHz大功率迴旋管进行电子迴旋共振加热(ECRH)的同时,以不同的方式向磁镜中注入电子束,进行了ECRH捕获电子束的实验研究。结果表明:由于电子束的提前注入,等离子体的预电离时间被大大地缩短。由上ECRH对电子束的捕获,使得热电子环参数得到很大的改善,热电子环的反磁β值约增加62%,对应反磁增加的捕获效率约为(30—40)%。在迴旋管输出约30kW的条件下,适应建立热电环的气体压力窗为(4.67—21.3)×10^-4Pa。 关键词：     

螺旋线迴旋加速器中粒子流通过非线性共振线(Q_ρ=(6/5))的研究

本文用电子计算机对N=6的螺旋线迴旋加速器中粒子流通过非线性共振线(Q_p=6/5)的动态过程进行了定量计算及分析。求得了在一定的加速电压下,粒子流在通过此共振线时的损失率。     

Stability of the Electron Cyclotron Resonance

We consider the magnetic AC Stark effect for the quantum dynamics of a single particle in the plane under the influence of an oscillating homogeneous electric and a constant perpendicular magnetic field. We prove that the electron cyclotron resonance is insensitive to impurity potentials.     

HL-1M装置边缘参数测量

在HL－1M装置上利用马赫／郎缪尔探针分别在欧姆放电,低杂波注入,中性束注入,离子回旋加热和电子回旋加热等情况下测量下刮离层和等离子体边缘的极向流速度和电场,得到了它们的径向分布,研究了LHW,NBI,ICRH和ECRH对改善等离子体约束性能,边缘粒子的径向传输的影响。     

From H. Kroemer and B. Lax to modern solid-state (semiconductor)cyclotron resonance masers

Presents an overview of mechanisms responsible for cyclotron resonance amplification in semiconductors as compared to that in the gyrotrons and a discussion of the ways to create beam-like and/or inverted distribution in the bulk of semiconductors by application of electric field is presented. Observation results on negative mass and light hole cyclotron resonance stimulated emission in Ge are discussed with the main emphasis on demonstration of the mechanisms responsible for the emissions. Some modern trends are also briefly considered     

Influence of an electric field on the magnetoabsorption in a field of resonant laser radiation

The frequency dependence of the coefficient of interband magnetoabsorption of a weak electromagnetic wave propagating in a constant electric field and in a field of resonant laser radiation at a frequency equal to the cyclotron frequency (infrared magnetic resonance) is calculated. The specific features observed in interband absorption of the electromagnetic wave in a uniform electric field are considered for the case in which the frequency of laser radiation is equal to the confinement frequency in a parabolic quantum well (infrared quantum-well resonance).     

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.     

Shift in cyclotron resonance of electrons on liquid helium surfaces

We calculate the increase in cyclotron resonance frequency for electrons trapped within dimples on a liquid helium surface, when a vertical electric field is applied in addition to the strong vertical magnetic field.     

Quantum transport in GaInAs-AlInAs heterojunctions,and the influence of intersubband scattering

Shubnikov-de Haas and cyclotron resonance results are presented for GaInAs-AlInAs heterojunctions in both perpendicular and tilted magnetic fields. Two electric subbands are occupied in zero magnetic field. Magnetic depopulation of the higher (E₁) subband is observed in both perpendicular and tilted orientations. This enables a demonstration of the importance of intersubband scattering in both resistivity and cyclotron resonance. A shift of the relative positions of the E_o and E₁ subbands by parallel magnetic fields is measured to be 0.26 meV/T².     

Energy band model and properties of electrons in bismuth

A new energy band model for bismuth electrons is presented which gives very good fits to several experiments (de Haas-van Alphen effect, cyclotron resonance, magnetic surface resonance, radio-frequency size effect) and reasonably good fits to other properties (limiting-point cyclotron resonance, tilt effect) as function of the orientation of the magnetic field.     

Propagation of terahertz waves in nonuniform plasma slab under "electromagnetic window"

The application of magnetic fields, electric fields, and the increase of the electromagnetic wave frequency are up-and-coming solutions for the blackout problem. Therefore, this study considers the influence of the external magnetic field on the electron flow and the effect of the external electric field on the electron density distribution, and uses the scattering matrix method (SMM) to perform theoretical calculations and analyze the transmission behavior of terahertz waves under different electron densities, magnetic field distributions, and collision frequencies. The results show that the external magnetic field can improve the transmission of terahertz waves at the low-frequency end. Magnetizing the plasma from the direction perpendicular to the incident path can optimize the right-hand polarized wave transmission. The external electric field can increase the transmittance to some extent, and the increase of the collision frequency can suppress the right-hand polarized wave cyclotron resonance caused by the external magnetic field. By adjusting these parameters, it is expected to alleviate the blackout phenomenon to a certain extent.     

Temperature dependence of the cyclotron resonance in graphene

The dynamic conductivity of graphene in a magnetic field under the conditions of cyclotron resonance has been calculated. The effect of the temperature on cyclotron resonance has been analyzed. So-called multiple resonances have been considered. A dimensionless quantity determining the width and amplitude of the cyclotron peak in the conductivity has been found. Coulomb corrections to the electronic spectrum have been discussed.