EAST装置电子回旋共振加热系统中央控制器设计

介绍了基于可编程逻辑门阵列(FPGA)芯片的电子回旋共振加热(ECRH)系统中央控制器的设计,阐述了中央控制器对输入的总控触发信号、等离子体电流信号、ECRH系统状态信号、高压输出状态信号、波输出状态信号、各类停止信号以及各输出控制信号等的处理与控制逻辑.对FPGA程序做了时序仿真,仿真结果表明,该控制器能够实时响应总...     

电子回旋共振等离子体源的数值模拟

采用自洽微波功率吸收的二维混合模型,对电子回旋共振等离子体源中的各种物理参量(电离速率、等离子体密度、位势、电子温度)进行数值模拟.结果表明:等离子体参数随运行条件(中性气压和微波功率)变化呈现出区域特征、饱和现象和振荡行为等非线性现象 关键词：     

电子回旋共振加热情形锯齿振荡的数值分析

采用磁重联模型与湍流模型,通过求解耦合了锯齿触发条件的一维输运方程,模拟了电子回旋共振加热(ECRH)情形下T-10托卡马克中锯齿振荡.其中之一是近轴的ECRH,另一个是远轴的ECRH,数值结果与实验的比较表明用湍流模型得到了较好的预测结果,相反,由于重联模型的一些基本缺陷,不可能由重联模型得到满意的结果. 关键词： 锯齿振荡 磁重联模型 湍流模型 电子回旋共振加热     

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...     

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。     

EAST电子回旋共振加热效果的数值模拟和分析

为了给EAST电子回旋共振加热物理实验提供理论依据和模拟预测,从电子热输运方程出发,运用CRONOS输运程序对不同等离子体和波参数下,电子回旋加热效果进行了数值模拟计算。给出不同电子回旋波功率、入射角、电子密度和纵场等参数对电子回旋加热效果的影响,预测在不同参数下,电子温度、等离子体总内能和能量约束时间的变化,分析了其原因,并与实验结果进行了初步的比较。     

EAST离子回旋共振加热系统调制型 高压电源研究

介绍了EAST离子回旋共振加热系统调制型高压电源的总体设计方案,详细讨论了电源模块的构造、电路和工作原理,对电源控制保护系统的组成部分及其功能做了全面的论述,对电源的调制和短路保护能力进行了实际测试,给出了相应的实验数据和波形,证明了电源设计方案的正确性和可靠性。     

离子回旋共振加热的电子加热

理论分析和实验结果都证明在离子回旋共振加热情况下,电子能直接从波吸收能量,其能量吸收机制是郎道阻尼和飞行时间磁泵阻尼。本文从线性化波的一般理论,导出了电子吸收功率和吸收特征长度的解析表示式,与其他结果进行了比较并做了简短的讨论。     

EAST离子回旋波加热1.5MW射频放大器的研究

介绍了EAST上ICRF辅助加热系统1.5MW射频信号源中工作频率为25～70MHz的末级功率放大器的研制工作,从最优工作参数、输入回路和输出回路三个主要方面详细分析了该级大功率宽频带射频放大器。经比较,分析结果和测试数据显示了很好的一致性,这为实现ICRF加热系统的可靠运行奠定了基础。     

Numerical simulation of electron cyclotron current drive characteristics on EAST

Electron cyclotron current drive （ECCD） will be applied in the EAST tokamak during its the new campaign. In order to provide theoretical predictions for relevant physical experiments, some numerical simulations of ECCD with the parameters of EAST have been can＇ied out by using TORAY-GA code based on the understanding of ECCD mechanisms. ECCD efficiencies achieved in different plasma and electron cyclotron （EC） wave parameters are given. The dependences of ECCD characteristics on EC wave injection angle, toroidal magnetic field, plasma density, and temperature are presented and discussed.     

Fokker-planck study of tokamak electron cyclotron resonance heating

A Fokker－Planck study is carried out for tokamak electron cyclotron resonance heating by writing the quasi-linear diffusion operator into a form adaptive to the collision operator and considering the wave absorption characteristics of both the O-mode and the X-mode in different magnetic surfaces. Though the Fokker－Planck code is non-relativistic in nature, however, if the relativistic resonance condition for the nearly perpendicularly propagating waves is treated suitably, we can obtain correct results. The energy loss mechanism through anomalous transport is also modelled using a suitable loss term. In the heating phase, the electron distribution deviates from the Maxwellian distribution substantially, which leads to non-linear absorption characteristics. The wave damping rate is non-linear and changes with time. The electron pressure is usually anisotropic under different conditions: p_{e⊥}/p_{e‖}>2 for different D_0 and τ_e.     

不同磁路下微型ECR中和器电子引出的模拟研究

电子回旋共振(ECR)中和器是微型ECR离子推力器的重要组成部分,其引出的电子用于中和ECR离子源的离子束流,避免了航天器表面电荷堆积,并且电子引出性能对推力器的整体性能起着重要作用.为了分析影响微型ECR中和器电子引出的因素,本文建立了二维轴对称PIC/MCC计算模型,通过数值模拟研究不同磁路结构对中和器的电子引出,及不同腔体长度对壁面电流损失的影响.计算结果表明, ECR区位置和引出孔附近磁场构型对中和器的电子引出性能至关重要.当ECR区位于天线上游,电子在迁移扩散中易损失,并且电子跨过引出孔前电势阱所需的能量更高.如果更多磁力线平行通过引出孔,中和器引出相同电子电流所需电压较小.当ECR区被天线切割或位于下游时,电子更易沿磁力线迁移到引出孔附近,从而降低了收集板电压.研究了同一磁路结构下不同腔体长度对电子引出的影响,发现增加腔体长度,使得更多平行轴线的磁力线通过引出孔从而避免电子损失在引出板表面,增加了引出电子电流.研究结果有助于设计合理的中和器磁路和腔体尺寸.     

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.     

微波电子回旋共振等离子体阴极电子束的实验研究

介绍了实验室研制的微波电子回旋共振(ECR)等离子体阴极电子束系统及初步研究结果，该系统包括微波ECR 等离子体源、电子束引出极、聚焦线圈等。通过测量水冷靶电流和靶上的束斑尺寸，实验研究了微波ECR 等离子体阴极电子束的流强、聚束性能等随电子束系统工作条件的变化。结果表明：微波输入功率越高、引出电压越高，引出电子束流强越大；工作气压对电子束流强的影响较复杂，随气压增加呈现出先降低后升高的特点；在7×10⁻⁴Pa 的极低气压下电子束流强可达75mA，引出电压9kV；能量利用率可达0.6；调整聚焦线圈的驱动电流，电子束的束斑直径从20mm 减小到13mm，电子束流强未有明显变化。     

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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。     

Unstable plasma characteristics in mirror field electron cyclotron resonance microwave ion source

Electron cyclotron plasma reactor are prone to instabilities in specific input power [3–7] region (150–450 watts). In this region power absorption by gas molecules in the cavity is very poor and enhanced input power gets reflected substantially without increasing ion density. There are abrupt changes in plasma characteristics when input power was decreased from maximum to minimum, it was observed that reflected power changed from <2% to ∼50%. Minimum two jumps in reflected power were noticed in this specific power region and these appear to be highly sensitive to three stub tuner position in the waveguide for this particular input power zone. Unstable plasma region of this source is found to be dependent upon the magnetic field strength. Some changes in reflected power are also noticed with pressure, flow and bias and they are random in nature.     

Electron cyclotron resonance heating in a short cylindrical plasma system

Electron cyclotron resonance (ECR) plasma is produced and studied in a small cylindrical system. Microwave power is delivered by a CW magnetron at 2.45 GHz in TE¹⁰ mode and launched radially to have extraordinary (X) wave in plasma. The axial magnetic field required for ECR in the system is such that the first two ECR surfaces (B = 875.0 G andB = 437.5 G) reside in the system. ECR plasma is produced with hydrogen with typical plasma density n^e as 3.2 × 10¹⁰ cm^-3 and plasma temperature T^e between 9 and 15 eV. Various cut-off and resonance positions are identified in the plasma system. ECR heating (ECRH) of the plasma is observed experimentally. This heating is because of the mode conversion of X-wave to electron Bernstein wave (EBW) at the upper hybrid resonance (UHR) layer. The power mode conversion efficiency is estimated to be 0.85 for this system. The experimental results are presented in this paper.     

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利用11/2-D平衡演化程序对EAST的首轮纯欧姆放电进行了数值模拟，获得的模拟结果与实验结果吻合得很好。同时，对放电全过程中的伏秒消耗进行了分析。