HT-6M托卡马克二次谐波离子回旋共振加热实验

报道在HT-6M托卡马克用28MH_z射频源对纯氢等离子体进行二次谐波离子回旋共振(ICRF)加热的实验,实验结果表明,对1/4周短天线,当天线输入功率为300kw时,天线功率密度可达1kw/cm~2,脉冲宽度为30ms,天线负载电阻为2(?).与理论估算值较为接近.实验得到的加热效率为1.5×10~13eV·cm~(-3)/kw,并观察到在ICRF加热时引起的较强的辐射以及高能电子的产生. 关键词：     

离子回旋共振加热的离子加热

本文在直住几何位形下用线性化动力论得到了离子能量吸收及吸收特征长度的解析表示式，离子能量吸收的主要物理机制是回旋阻尼，波与离子的共振吸收条件是ω－ｌωｃｉ＝ｋⅡνⅡ，其中ω和ωｃｉ分别是波的频率和离子回旋频率，ｋⅡ和ｖⅡ是平行于主磁场方向的波矢和离子速度的分量，ｌ为整数。在等离子体参量慢变化的假定下，也得到了能量吸收半宽度的表示式。结合托卡马克的各种具体情况分别讨论了各种离子回旋共振加热模式的...     

极化力导致回旋频率变化

带电粒子在一个均匀磁场中的回旋频率为qB/m ,其中q和m是粒子的电荷与质量 ,B是磁感应强度 .这一关系式是使用离子回旋共振质谱仪进行分子质量对比的基础 ,其应用范围涵盖了鉴别生物分子、研究化学反应速率直到确定原子光谱的精细结构常数 .美国麻省理工学院 (MIT)的物理学家Da     

EAST装置离子回旋加热天线电流带热结构分析

介绍了EAST装置新型离子回旋加热(ICRH)天线电流带的设计结构。通过对电流带实际工况的计算得出电流带的工作温度分布,以此来模拟实际工作条件下电流带的热载荷承受能力以及对电流带结构的影响。论证了在实际工况热载荷条件(0.2MW)下,电流带辐射面温度及电流带整体结构强度满足设计要求。     

超灵敏小型回旋加速器质谱计的研制

超灵敏小型回旋加速器质谱计的研制陈茂柏（中国科学院上海原子核研究所，上海２０１８００）１９４７年，美国芝加哥大学教授利比（Ｌｉｂｂｙ）首先提出测定１４Ｃ放射性进行断代的方法，为此他于６０年代获得了诺贝尔奖金。现在，１４Ｃ放射法主要利用液体闪烁计数器探...     

HT-7 Tokamak离子回旋波和低杂波等离子体逃逸电子行为研究

HT-7 Tokamak拥有离子回旋波(ICRF)和低杂波(LHW)两套加热系统.ICRF主要对加热离子有比较好的加热效果,LHW则主要是通过电子Landau阻尼加热电子.除此之外,在ICRF和LHW协同加热的条件下,可以对等离子体产生更有效的加热效果,增加等离子体的聚变反应截面,增加聚变中子产额.本文报道了LHW对改善ICRF和等离子体耦合的重要作用,ICRF和LHW加热等离子体中电子温度随时间的演化过程,计算了放电过程中电子逃逸的阈值能量,分析了逃逸电子的产生过程,以及放电过程中的中子产额.研究结果发     

HL-1M装置离子回旋共振加热系统及初步实验

新建成的HL-1M装置离于回旋共振加热(ICRH)射频系统,经工程联调,已达到输出功率500kW、脉宽100ms、频率26～36MHz。在环向场B     

在HT-6B托卡马克上的电子回旋共振预电离实验

本文给出了1986年5月在HT-6B上进行的二倍频ECR预电离实验的结果。实验观察到只要回旋共振层落在托卡马克小截面内都可获得正常放电波形;等离子体电流基本上是和环电压同时出现的;等离子体环电压下降30％左右。同时还观察到ECR预电离对减少放电初期的硬X射线和轻杂质(CⅣ)的辐射有比较明显的作用。     

微型电子回旋共振离子推力器离子源结构优化实验研究

微型电子回旋共振(ECR)离子推力器可满足微小航天器空间探测的推进需求. 为此, 本文开展直径20 mm的微型ECR离子源结构优化实验研究. 根据放电室内静磁场和ECR谐振区的分布特点, 研究不同微波耦合输入位置对离子源性能的影响, 结果表明环形天线处在高于ECR谐振强度的强磁场区域时, 微波与等离子体实现无损耦合, 电子共振加热效果显著, 引出离子束流较大. 根据放电室电磁截止特性, 结合微波电场计算, 研究放电容积对离子源性能的影响, 实验表明过长或过短的腔体长度会导致引出离子束流下降甚至等离子体熄灭. 经优化后离子源性能测试表明, 在入射微波功率2.1 W、氩气流量14.9 μg/s下, 可引出离子束流5.4 mA, 气体放电损耗和利用率分别为389 W/A和15%.     

HT-7装置电子回旋辐射系统接收天线改进

为了提高HT-7装置上等离子体电子回旋辐射(ECE)超外差诊断系统的极向分辨率,根据高斯光学原理,分析了诊断系统天线的改进方案。优化了天线的圆形角锥喇叭尺寸和凸透镜参数以及在装置上的相对位置,使天线接收到的等离子体ECE异常模二次谐波辐射的高斯光束束半径只有30mm左右,能量的高斯光学性质损失不大于13%。     

Penning阱离子谱中奇异峰分析

本文报道Penning离子阱中离子谱出现的奇异峰,提出鉴别它的方法,分析其产生的原因和消除它的可能性,还利用该机制设计出具有高分辨率的探测存储离子的新方法.     

Study of particle behaviour at the edge in HT-7 tokamak

The cross-field diffusion coefficient (D_⊥) at the edge in the HT-7 tokamak is close to the Bohm value when the line average electron density ranges from 1.5×10^{19} to 3.0×10^{19}m^{-3}. The energy profile of the particles is derived directly from the H_α(D_α) line shape; the dissociative excitation of molecules is dominating when the local electron temperature is above 10eV. By means of the Monte Carlo method the D_α line shape is also simulated. We find that the molecular dissociation contributes to 57% of neutral atoms and 53% of emission intensity in front of the limiter, and 85% of neutral atoms and 82% of emission intensity in front of the wall. The influence of atomic and molecular processes on the energy balance is discussed for the scrape-off layer (SOL), and the power loss from molecular dissociation is found to be 6×10^4kW at the SOL. The ion Bernstein wave (IBW) can effectively suppress the magnetohydrodynamic behaviour, the fluctuation levels and the turbulence; the D_⊥ in front of the limiter declines from 0.84 to 0.2m^2·s^{-1} and the particle confinement time rises from 9 to 12ms.     

AC operation and runaway electron behaviour in HT-7 tokamak

Operation of HT-7 tokamak in a multicycle alternating square wave plasma current regime is reported. A set of AC operation experiments, including LHW heating to enhance plasma ionization during the current transition and current sustainment, is described. The behaviour of runaway electrons is analysed by four HXR detectors tangentially viewing the plasma in the equatorial plane, within energy ranges 0.3--1.2~MeV and 0.3--7~MeV, separately. High energy runaway electrons (\sim MeV) are found to circulate predominantly in the opposite direction to the plasma current, while the number of low energy runaway electrons (\sim tens to hundreds of keV) circulating along the plasma current is comparable to that in the direction opposite to the plasma current. AC operation with lower hybrid current drive (LHCD) is observed to have an additional benefit of suppressing the runaway electrons if the drop of the loop voltage is large enough.     

Study of particle transport in ac plasmas on HT-7 tokamak

The particle transport coefficients were investigated in ac plasmas by density modulation method on HT-7 tokamak. It is observed that the particle diffusion coefficient (D) is almost the same in various cases and varies with the electron density. The convection velocity (V) is equal to the value of inward pinch velocity (VE×B) for low and high density discharges. The particle confinement time becomes much higher when the directions of plasma current and toroidal field are uniform.     

Lower hybrid current drive experiments with graphite limiters in the HT-7 superconducting tokamak

Recent progress of lower hybrid (LH) experiments with new graphite limiters configuration in the HT-7 tokamak is presented. The lower hybrid current drive (LHCD) efficiency can be determined by fitting based on experimental data. Improved particle confinement was observed via LHCD (P_LHW>300 kW) characterized by the particle confinement time τ_p increased about 1.56 times. It is found that runaways are suppressed during loop voltage is decreasing at the flat-top phase of LH discharges. The main limitations of pulse length are presented in long-pulse experiments with new limiter configuration.     

HT-7托卡马克等离子体slide-away放电研究

在HT-7托卡马克上,只在等离子体放电击穿阶段充气,击穿后关闭充气阀门,让装置内真空室器壁的出气维持放电的进行,通过密度衰减实现了slide-away放电.实验分析了不同等离子体电流平台下的slide-away放电模式的密度阈值,以及相同充气量的条件下放电等离子体电流对实现slide-away放电的影响.研究了slide-away放电模式下密度提升对等离子体放电状态的影响.结果发现,slide-away放电模式下的密度提升使得H_a线辐射强度增强,等离子体中超热电子的约束性能变差,等离子体芯部的超热电子减少,高能逃逸电子厚靶轫致辐射增加. 关键词： slide-away放电 托卡马克 等离子体 逃逸电子     

On the theory of classical cyclotron resonance line broadening in two- and three-dimensional semiconductors

A broadening of the absorption line of the classical cyclotron resonance (CR) in two- and three-dimensional semiconductors with neutral impurities of arbitrary depth is investigated. A dependence of the half-width of the classical CR line on the impurity characteristics (depth and range of the potential) is obtained in the wide range of the parameters. The broadening is studied within the Born approximation, and also at resonant and non-resonant scattering. Fundamental differences between the line broadening by neutral impurities in two- and three-dimensional semiconductors are revealed. An alternative explanation of classical experiments on electron scattering by neutral impurities (donors) is proposed.     

HT-7托卡马克大功率低混杂波电流驱动的实验研究

在HT-7超导托卡马克成功进行了大功率（P_LHW=100—800 kW,f=2.45 GHz）低混杂波电流驱动实验.研究了不同入射功率和等离子体密度下的低混杂波电流驱动效率.获得了以平均电子密度增加、氘阿尔法（D_α）线辐射减少为特征的粒子约束改善;粒子约束时间τ_p增加了约1.5倍.仔细研究了能量约束时间与等离子体密度和低混杂波功率的关系. 关键词： 托卡马克 低混杂波 约束改善 电流驱动效率     

Energy limit of runaway electrons in the HT-7 tokamak

The energy limit of runaway electrons in the HT-7 tokamak is investigated by measuring the synchrotron radiation originated from the runaway electrons and the hard X-ray radiation (HXR) when they hit the first wall. An upper boundary on the runaway energy can appear due to the resonance between the electron gyromotion and the magnetic field ripple in the low field side. The experimental derived maximum energy in the core is about 26 MeV, and maximum energy in the edge region is blocked to no more than 5 MeV. This resonance interaction of runaways with the nth harmonic of the magnetic field ripple can account for the observed energy gap of the runaways.     

相干结构Blob在HT-7托卡马克边界的传播

相干结构Blob的间歇爆发清晰地反映在HT-7托卡马克边界探针的离子饱和流信号中,Blob 的径向传播在近刮削层堆积出一个温度和密度的平台区,使密度和温度分布偏离了指数分布.条件平均方法提示了间歇脉冲结构空间分布的均匀性,Blob内部等离子体参数远高于背景等离子体参数,并且呈现出涡旋的形态.最后闭合磁面附近的数据显示,...