AST-ICRH天线相位的控制研究

EAST超导托卡马克是我国开展受控核聚变研究的新一代实验装置,离子回旋波加热(ICRH)是在该装置中加热等离子体的重要手段之一.要高效地实现波加热就要很好地控制相位,设计了一套相位控制系统,可以有效地调节加热系统天线的相位关系,从而很好地实现波加热.     

EAST-ICRF传输线驻波电流测量

为了测量托卡马克放电期间离子回旋加热系统的传输线电流值,利用电流探针搭建了传输线电流测量系统。对传输线电流测量原理进行简单介绍,并对电流探针的特性进行分析研究,确保电流探针的性能。将实验中用电流探针测得的传输线电流值与电压探针拟合计算得到的传输线电流值进行了对比,验证了传输线电流测量系统的可靠性。     

基于FPGA的EAST-ICRH天线相位测量研究

离子回旋波加热(ICRH)是EAST超导托卡马克核聚变实验装置加热等离子体的重要手段之一,而离子回旋加热天线电流带之间的相位关系影响到天线的加热效果。论文提出了一种基于FPGA的ICRH天线相位测量方案,采用双AD8302模块以及新的算法解决了相位测量的二值性和非线性误差问题,测量精度高。同时利用FPGA可编程的特点,使得系统的设计变得简洁灵活,便于后期功能的扩展。     

The Influence of Neutral Beam Injection on the Heating and Current Drive with Electron Cyclotron Wave on EAST

Both neutral beam injection(NBI) and electron cyclotron resonance heating(ECRH) have been applied on the Experimental Advanced Superconducting Tokamak(EAST)in the 2015 campaign. In order to achieve more effective heating and current drive, the effects of NBI on the heating and current drive with electron cyclotron wave(ECW) are analyzed utilizing the code TORAY and experimental data in the shot #54411 and #54417. According to the experimental and simulated results, for the heating with ECW, NBI can improve the heating efficiency and move the power deposition place towards the inside of the plasma. On the other hand, for the electron cyclotron current drive(ECCD), NBI can also improve the efficiency of ECCD and move the place of ECCD inward. These results will be valuable for the center heating, the achievement of fully non-inductive current drive operation and the suppression of magnetohydrodynamic(MHD) instabilities with ECW on EAST or ITER with many auxiliary heating methods.     

EAST离子回旋加热系统高功率射频放大器阳极电源的研制

离子回旋共振加热是EAST超导托卡马克核聚变实验中重要的辅助加热手段。高性能的高功率射频放大器阳极电源对整个加热系统的稳定运行起重要作用。本工作设计了基于脉冲阶梯调制（PSM）技术的阳极电源及其控制保护系统,通过采集电源的实验数据对电源的设计进行了验证。实验结果证明,本阳极电源的设计和参数选择均是合理正确的,电源的开通和关断以及控制保护的数据指标完全达到设计要求。     

Electron Cyclotron Harmonic Wave Heating in Tokamak Plasmas with Different Polarization Modes

Electron cyclotron heating on HL-2A has been simulated by TORAY-GA with a second harmonic extraordinary wave and a fundamental ordinary wave. The results show that the wave absorption of the second harmonic extraordinary wave is better than that of the fundamental ordinary wave. In order to understand the interaction mechanism between electrons and the two different polarization modes, the energy exchange between electrons and the two modes are theoretically analyzed, and it is found that the coupling intensity described by the Bessel function and different polarizations of the two modes are the main reasons leading to the above phenomenon. The theoretical results of this study fit well with the simulated and numerical results.     

电子回旋波Ohkawa机制电流驱动计算

从电子回旋波电流驱动的机制出发,理论推导出了Boozer-Fisch电流与Ohkawa电流的计算表达式,并给出了具体的计算方法。数值模拟结果表明:电子回旋波的波功率沉积在托卡马克高场侧的离轴位置时,Ohkawa电流较小,Boozer-Fisch电流能达到较大值;波功率沉积在低场侧的离轴位置时,通过调整波参数,有效抑制Boozer-Fisch电流,能充分利用Ohkawa电流的优势使离轴驱动电流同样能达到较大值。     

Ion Bernstein Wave Heating Experiments in HT-7 Superconducting Tokamak

Ion bernstein wave （IBW） experiments have been carried out in HT-7 superconducting tokamak in recent years. The electron heating experiments concentrated on deuterium plasma with an injected RF power up to 350 kW. The global heating and the localized heating can be seen clearly by adjusting the ICRF resonance layer positions. The on-axis and the off-axis electron heating were realized by arranging the target plasma parameters properly. Experimental results show that the maximum increment of electron temperature was more than 1 keV, the electron temperature profile was modified by IBW under different plasma conditions and the improvements of both energy and particle confinements have been obtained.     

EAST离子回旋系统液态相移器的理论设计

对EAST离子回旋系统液态相移器的原理进行了理论分析和计算,结果表明:利用液态相移器可产生相位差,从而可用离子回旋波进行电流驱动。另外,液态相移器也可与单支节液态调配器结合使用,构成传输线阻抗匹配系统。     

积分分离的电子回旋共振加热高压脉冲电源模糊控制研究

基于四极管的电子回旋共振加热负高压脉冲电源是支持回旋管工作的关键组件,对稳态误差精度和响应速度等性能有较高的要求。分析了电源系统的工作原理,给出了数学模型。针对四极管的非线性特点和电源的控制要求,将智能控制方法与电源技术相结合,提出积分分离模糊控制器的控制策略。通过仿真实验,与传统PID控制策略进行比较,结果表明,该控制器具有抑制超调、自适应自调节的功能,为实现高性能的负高压脉冲电源提供了一种新的控制策略,同时也为智能化数字控制的实现打下基础。     

The Influence of Iron on Ammonium Ion Generation from Nitrate Ion in Liquid Phase

Flue gas cleaning in discharge plasma process has been Studied intensively and we have tried to remove the NOx and S02 using the wet-type plasma reactor. In this system, NO is oxidized to NO2 and absorbed as NO3^-, and SO2 is absorbed as SO3^2- and oxidized in the liquid to SO4^2-. But the concentration of NO3^- was saturated and the absorption of NOx and SO2 was inhibited. Then, the reduction of NO3^- in the liquid is required. We examined the reductive reaction of NO3^- to NH4^ using discharge above the liquid surface then the pH value of the liquid was changed to alkaline slightly. When the Fe plate was used as a ground electrode in the liquid, NH4^ was generated. Then, the relation between the generation of NH4^ and Fe ions (Fe^2 and Fe^3 ) was studied. When Fe^2 was presented in the liquid, NH4^ was generated and Fe^2 was oxidized to Fe^3 . Fe^2 is required to generate NH4^ from NO3^-. When NH4^ was generated from NO3^-, both the calculated pH value from NH4^ concentration and the measured pH value indicated a similar value. From these results, the discharge above the liquid surface was effective to convert NO3^- to NH4^ and the reductive reaction leads to more absorption of NO3^-. These results showed that the wet-type plasma reactor is effective for NOx and SO2 removal system.     

Varying Electron Cyclotron Resonance Heating on the Levitated Dipole Experiment

Plasmas in the Levitated Dipole Experiment (LDX) are formed and sustained currently via two electron cyclotron resonance heating (ECRH) sources: 2.5 kW at 2.45 GHz and 2.5 kW at 6.4 GHz. An important topic being investigated is how varying the ECRH affects the confinement and stability of the plasma. We report the results of using different operational combinations of our RF sources, such as varying the power composition, changing the power levels, and sequencing of the onset time.     

Influence of Superathermal Electrons on Central Plasma Relaxation oscillations during Localized Electron Cyclotron Heating on the HL—1M Tokamak

During initial studies of ECRH in the HL-1M tokamak,non-standard central MHD activities,such as saturated wawtooth,partially saturated sawtooth,double sawtooth,and the strong m=1 bursts have been observed while changing the heating location,the ECRH power.the plasma density,Complete suppression of sawtooth is achieved for the duration of the ECRH.when the heating power is applied on the high-fiedl side of low-density plasma,and exceeds a threshold value of power .The m=1 bursts riding on the ramp phase of sawtooth can only be excited when the ECRH locaxation activities are produced or suppressed are described.Experimental results imply that the energetic electrons generated during ECRH are responsible for the modification/or stabilization/or excitation of the instability.Near the q=1 surface,the passing electrons play the role of reducing the shear and tending to stabilize the sawtooth activity,while the barely-trapped electrons play the role of enhancing or driving an internal kink instability.     

Status of the ITER Ion Cyclotron H&CD system

The ongoing design of the ITER Ion Cyclotron Heating and Current Drive system (20 MW, 40–55 MHz) is rendered challenging by the wide spectrum of requirements and interface constraints to which it is subject, several of which are conflicting and/or still in a high state of flux. These requirements include operation over a broad range of plasma scenarios and magnetic fields (which prompts usage of wide-band phased antenna arrays), high radio-frequency (RF) power density at the first wall (and associated operation close to voltage and current limits), resilience to ELM-induced load variations, intense thermal and mechanical loads, long pulse operation, high system availability, efficient nuclear shielding, high density of antenna services, remote-handling ability, tight installation tolerances, and nuclear safety function as tritium confinement barrier. R&D activities are ongoing or in preparation to validate critical antenna components (plasma-facing Faraday screen, RF sliding contacts, RF vacuum windows), as well as to qualify the RF power sources and the transmission and matching components. Intensive numerical modeling and experimental studies on antenna mock-ups have been conducted to validate and optimize the RF design. The paper highlights progress and outstanding issues for the various system components.     

The Efficiency of Ion Stochastic Heating by a Monochromatic Obliquely Propagating Low-Frequency Alfven Wave

Abstract The process of ion heating by a monochromatic obliquely propagating low-frequency Alfven wave is investigated. This process can be roughly divided into three stages： at first, the ions are picked up by the Alfven wave in several gyro-periods and a bulk velocity in the transverse direction is achieved; then, the ions are scattered in the transverse direction by the wave, which produces phase differences between the ions and leads to ion heating, especially in the perpendicular direction; and finally, the ions are stochastically heated due to the sub- cyclotron resonance. In this paper, with a test particle method, the efficiency and time scale of the ion stochastic heating by a monochromatic obliquely propagating low-frequency Alfven wave are studied. The results show that with the increase of the amplitude, frequency, and propagation angle of the AlDen wave, the efficiency of the ion stochastic heating increases, while the time scale of the ion stochastic heating decreases. With the increase of the plasma beta β, the ions are stochastically heated with less efficiency, and the time scale increases. We also investigate the heating of heavy ion species （He2＋ and O5＋）, which can be heated with a higher efficiency by the oblique Alfven wave.     

Performance of a Penning Ion Source in the Oak Ridge Isochronous Cyclotron

One year of operation of a heavy-ion Penning source in the Oak Ridge Isochronous Cyclotron has resulted in the acceleration of a number of isotopes of 17 elements, ranging from boron to tantalum. The method of positive identification of these beams and the operational techniques used to develop certain beams are described. Comparison of the extracted particle current for a given charge state with the calculated ionization potential has resulted in a systematic understanding of particle currents to be expected for undeveloped beams. In particular, shell effects and total ionization potential must both be considered in predicting beam intensities. The particle currents of ArR8+ Ar9+ and Ar10+ provide a sensitive test for the comparison of multiple and single impact calculations. The data are in agreement with multiple impact calculations. Also, low energy x-rays emitted from the Penning source have been detected and the observed spectra characterize the two modes of source operation.     

ITER中的电子回旋波电流驱动模拟

通过将相对论Fokker-Planck方程与波迹方程联合求解,对ITER(国际热核实验反应堆)参数下的电子回旋波电流驱动进行了数值模拟。结果表明,当波的环向发射角度不太大时,波功率沉积将发生在ITER的强场侧。当环向发射角度为21°时,电子回旋波的能量在等离子体中心区域被吸收并驱动起等离子体中心区域的电流。当发射角度变大时,电子回旋波将在弱场侧沉积功率。当发射角度为20°～30°时,能够驱动归一化的径向位置(r/a)小于0.35区域内的等离子体电流,并有较高的电流驱动效率。     

EAST电子回旋波与低杂波双波协同的数值模拟

为在EAST装置中优化电子回旋波与低杂波双波协同的电流驱动效率,从而获得更大的协同驱动电流以维持长脉冲运行,本文以双波协同驱动电流的物理机制为基础,运用模拟程序C3PO/LUKE对EAST参数下电子回旋电流驱动与低杂波电流驱动的协同效果进行了数值模拟计算,给出了协同电流和协同因子。计算结果表明：当两波驱动电流密度峰值的位置一致时协同效果最佳;而电子密度和电子温度的增加可能导致两波重叠区域的变化进而影响协同效果。