HL—1装置中LHCD和等离子体参数的关系

本文了在ＨＬ－１托卡马克的不同放电阶段的低混杂波驱动特性，给出了驱动电流及驱动效率和等离子体参数，如电子平均密度ｎｃ，等离子体电流Ｉｐ及纵向磁场的关系，也给出和分析了波驱动和入射波功率的关系，在放电平段，对正反向驱动效率进行了研究和比较。     

低杂波驱动中增强的电子回旋辐射

本文基于三波共振相互作用，研究了低杂波驱动的高频电磁辐射。Ｖｌａｓｏｖ方程的导向中心形式被用来推导包括动力效应的耦合系数。在小ｋｚ近似下，给出了耦合系数中的所有速度积分。对一般非线性色散关系进行了详细理论分析，结果表明：（１）低杂泵浦波可以激发电子Ｂｅｒｎｓｔｅｉｎ波，并伴随高频电磁辐射；（２）以这种方式激发的电磁辐射是一种热电子回旋辐射，辐射强度随着等离子体温度和密度的增加而增加。这样我们可以假定，本非线性不稳定性可以成为低杂波驱动中增强电子回旋辐射及等离子体电子回旋辐射的起因。     

低混杂波电流驱动下注入杂质的输运

在欧姆放电和低混杂波电流驱动条件下,应用激光吹气技术注入金属杂质,用真空紫外谱仪测量了杂质线的辐射,给出了ＨＬ－１Ｍ 装置欧姆等离子体和低混杂波电流驱动等离子体杂质输运的研究结果。用杂质输运程序ＬＢＯ进行数值模拟,得出了等离子体中杂质的扩散系数Ｄ（ｒ） 和对流速度ｖ（ｒ）。在低混杂波电流驱动条件下,等离子体杂质的输运系数相对欧姆放电等离子体杂质的输运系数减小了５０％ 左右。结果表明,在ＨＬ－１Ｍ 装置上低混杂波电流驱动等离子体相对通常欧姆等离子体杂质的约束性能明显得到了改善     

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     

托卡马克等离子体不同运行模式下的电子回旋波电流驱动

在给定等离子体密度分布下，从电子、离子的能量方程出发，根据不同运行模式下等离子体的热传导率不同，分别求出了中心负剪切模式，常规剪切H模式和L模式下的等离子体温度分布，然后通过求解波迹方程与相对论情况下的Fokker-Planck方程，分别计算了这些模式下的电子回旋波电流驱动和波功率沉积.得到在中心负剪切下，驱动电流最大，驱动效率最高，功率沉积和电流分布区间跨度大；在常规剪切H模式下，驱动电流较小，分布区间跨度比较窄，驱动效率相对较低；在常规剪切L模式，驱动电流效率最低，分布区间跨度也非常集中. 关键词： 托卡马克 电子回旋波电流驱动 中心负剪切 常规剪切     

托卡马克中电子回旋波与低杂波协同驱动的物理研究

揭示了电子回旋波与低杂波协同驱动等离子体并获得协同电流的机理. 从物理上阐述了双波协同驱动在相空间上和在电流剖面上所需满足的匹配关系. 通过计算机模拟研究展示了协同驱动的净增电流与波功率之间存在的非线性关系, 并对其给出了物理上的解释.本文工作将为相关实验的设计和分析提供物理上的支撑.     

HT-7低杂波电流驱动效率与有效电荷数及电子温度的关系

在HT-7超导托卡马克中进行了低杂波电流驱动的功率扫描实验,功率变化范围为100kW至700kW,频率为2.45GHz。研究了等离子体平均有效电荷数及电子温度与低杂波功率之间的关系。给出了不同功率下低杂波电流驱动效率与有效电荷数及电子温度之间的关系:HT-7装置低杂波驱动效率与电子温度成正比,与有效电荷数成反比。指出了动态杂质控制是改善低杂波电流驱动效率的关键问题。     

HL-2A装置的LHCD运行区域与驱动电流分布控制

讨论了低杂波电流驱动（LHCD）实验中电流驱动效率、电流分布控制与等离子体参数和入射波谱的关系,以及波的可近性对确定功率沉积分布的作用。讨论了控制电流密度分布的方法及在HL－2A装置上实现中心负剪切位形的可能性。     

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采用高斯光束的研究方法,结合Fokker-Planck方程,在堆级等离子体条件下模拟了发射波功率密度的改变对电子回旋波功率沉积以及电流驱动的影响。结果表明,高功率密度的波束会拓宽功率沉积剖面,使功率沉积的位置略有外移,电流驱动效率略有降低。     

低混杂波驱动电流对等离子体电导率的影响

本文考虑了波驱动通量对磁场位形以及电子密度和温度的空间分布的依赖,应用伴随关系,计算了低混杂波驱动的等离子体电导率的空间分布。结果表明,注入功率谱对电导率空间分布的影响相当敏感,等离子体环外侧的电导率略高于内侧的电导率。但是不论在外侧或内侧,随着离子电荷数增大,波驱动的等离子体电导率降低,而它与斯必泽-亥姆电导率之比却增大。     

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在EAST上通过分析剩余环电压与低杂波功率之间的关系,计算得到了低杂波电流驱动效率。采用归一化功率,即功率对等离子体电流、电子密度、等离子体大半径以及有效电荷数归一化,将所有数据绘制在同一曲线中,这样可以得到不同等离子体参数下的低杂波电流驱动效率。实验得到低杂波电流驱动效率η0=(0.5~1.3)×1019 A.m-2.W-1,在等离子体电流Ip=277kA、低杂波功率PLH=681kW条件下,实验得到长达3s的低杂波全波驱动。     

EAST装置低杂波电流驱动效率分析

在EAST上通过分析剩余环电压与低杂波功率之间的关系,计算得到了低杂波电流驱动效率。采用归一化功率,即功率对等离子体电流、电子密度、等离子体大半径以及有效电荷数归一化,将所有数据绘制在同一曲线中,这样可以得到不同等离子体参数下的低杂波电流驱动效率。实验得到低杂波电流驱动效率η₀=(0.5~1.3)×10¹⁹ A.m^-2.W^-1,在等离子体电流I_p=277kA、低杂波功率P_LH=681kW条件下,实验得到长达3s的低杂波全波驱动。     

CFETR低杂波电流驱动数值模拟研究

利用射线追踪和福克-普朗克方程,研究了CFETR上驱动电流和功率沉积对低杂波注入位置和耦合波谱的依赖关系,讨论了边界非线性效应对电流驱动与功率沉积的影响,给出了低杂波平行折射率和低杂波注入位置的一个优化值。初步数值计算表明：边界非线性效应会导致驱动电流降低;不考虑低杂波非线性效应时,驱动电流的差异约为6%左右,小于考虑该效应时的差异(~25%)。     

Simulation on effect of poloidal power spectrum on lower hybrid wave propagation

The coupling of lower hybrid wave to the plasma is a crucial issue for efficient current drive in tokamaks. This paper establishes a new coupling model which assumes the antenna to be a curved face and the plasma to be a cylinder. Power spectrum considering the coupling between wave-guides in both poloidal and toroidal direction is simply estimated and discussed. The effect of the poloidal wave vector on wave propagation, power deposition and driven current is also investigated with the help of lower hybrid current drive code. Results show that the poloidal wave vector affects the ray tracing, and also has effect on power deposition and driven current. The effect of the poloidal wave vector on power deposition and driven current profile depends on plasma parameters. Preliminary studies suggest that it seems possible to control the current profile by adjusting the poloidal phase difference between the waveguide in poloidal direction.     

Parametric decay instabilities of the fast wave in the lower hybridfrequency regime

Three possible delay instabilities of the fast wave in the lower hybrid frequency regime are presented. It has been considered that a fast wave may decay into a high-frequency, lower hybrid wave and a low-frequency wave, either the ion-Bernstein wave, ion-acoustic wave, or kinetic Alfven wave. Explicit expressions for growth rates, homogeneous thresholds, and convective thresholds have been given. Applications have been pointed out in tokamak plasma during current drive experiments and magnetospheric plasmas. For example, for PLT tokamak parameters, the convective threshold for the decay instability of the fast wave into lower hybrid and ion acoustic wave is ~180 W/cm²     

低杂波控制电流分布与改善约束研究

在HT-7超导托卡马克装置上利用低杂波电流驱动有效地控制了等离子体电流分布,并使等离子体约束性能改善。数值模拟与硬X射线测量结果均表明,低杂波的发射功率谱、纵场和等离子体密度对改变等离子体电流分布有明显的影响。在优化低杂波电流驱动实验参数的条件下,等离子体密度、温度分布发生了理想的变化。在电子和离子温度分布上出现了内部输运垒,同时等离子体的能量约束时间和粒子约束时间均有提高。     

EAST低混杂波功率沉积和电流驱动剖面控制的数值模拟

对原有的低混杂波电流驱动模拟程序进行改进,使之能够研究EAST上如何控制低混杂波功率沉积和电流驱动分布.在EAST非圆截面的平衡位形下,应用改进后的程序详细计算不同低混杂波功率谱、等离子体密度和温度分布对低混杂波功率沉积位置和电流驱动剖面分布的影响.通过计算发现,选取合适的低混杂波功率谱,等离子体温度分布和密度分布可以对功率沉积位置和电流驱动分布的剖面进行控制;调节等离子体温度分布可以很好的控制低混杂波近轴电流驱动分布和离轴电流驱动分布.     

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The synergy current drive by combining electron cyclotron wave (ECW) with lower hybrid wave (LHW) can be used to either increase the noninductive current drive efficiency or shape the plasma current profile. In this paper, the synergy current drive by ECW and LHW is studied with numerical simulation. The nonlinear relationship between the wave powers and the synergy current of ECW and LHW is revealed. When the LHW power is small, the synergy current reduces as the ECW power increases, and the synergy current is even reduced to lower than zero, which is referred as negative synergy in the this context. Research shows that the mechanism of the negative synergy is the peaking effect of LHW power profile and the trapped electrons effect. The present research is helpful for understanding the physics of synergy between electron cyclotron current drive and lower hybrid current drive, it can also instruct the design of experiments.     

Modulation instability of lower hybrid waves leading to cusp solitons in electron–positron(hole)–ion Thomas Fermi plasma

Following the idea of three‐wave resonant interactions of lower hybrid waves, it is shown that quantum‐modified lower hybrid (QLH) wave in electron–positron–ion plasma with spatial dispersion can decay into another QLH wave (where electron and positrons are activated, whereas ions remain in the background) and another ultra‐low frequency quantum‐modified ultra‐low frequency Lower Hybrid (QULH) (where ions are mobile). Quantum effects like Bohm potential and Fermi pressure on the lower hybrid wave significantly reshaped the dispersion properties of these waves. Later, a set of non‐linear Zakharov equations were derived to consider the formation of QLH wave solitons, with the non‐linear contribution from the QLH waves. Furthermore, modulational instability of the lower hybrid wave solitons is investigated, and consequently, its growth rates are examined for different limiting cases. As the growth rate associated with the three‐wave resonant interaction is generally smaller than the growth associated with the modulational instability, only the latter have been investigated. Soliton solutions from the set of coupled Zakharov and NLS equations in the quasi‐stationary regime have been studied. Ordinary solitons are an attribute of non‐linearity, whereas a cusp soliton solution featured by nonlocal nonlinearity has also been studied. Such an approach to lower hybrid waves and cusp solitons study in Fermi gas comprising electron positron and ions is new and important. The general results obtained in this quantum plasma theory will have widespread applicability, particularly for processes in high‐energy plasma–laser interactions set for laboratory astrophysics and solid‐state plasmas.