ITER高能alpha粒子轨道损失模拟研究

基于蒙特卡罗方法和无碰撞模型,采用测试粒子模拟方法,研究ITER等离子体中高能alpha粒子在无磁扰动和有磁扰动情况下分布与损失规律。结果表明:在无磁扰动条件下,alpha粒子的损失比例约为0.83%,这些损失的alpha粒子的初始位置主要位于靠近等离子体边界(最外层闭合磁面)的地方;在低频有磁扰动条件下,随着磁扰动幅度的增加,磁岛宽度增加,高能alpha粒子的损失率相应增加,但是其损失率仍然比较小(2%);损失的高能alpha粒子的初始飞行方向大部分为逆等离子体电流方向,而它们在飞出等离子体边界时的飞行方向大部分为顺等离子体电流方向,所有损失的alpha粒子几乎都是从等离子体赤道面以下飞出。     

DⅢ—D托卡马克的初步振荡通量电流驱动实验

在ＤⅢ－Ｄ托卡马克上作了振荡通量螺旋性注入的初步实验。环向通量受编程等离子体拉长的调制。不直接编程表面电压，而是用在一定相移下的周期调制将等离子体电流编程。从螺旋性注入的角度讨论了，并且也通过调制等离子体横越场的运动引入了这种调制的理论原理。由于初级绕组与等离子体电流充分耦合，所以拉长的幅度和相位受等离子体电流变化的影响，其行为与编程的不一样。由于这个原因，螺旋性注入感应的电压较低，故本实验没有试     

HL-1M等离子体的复合锯齿振荡

用软X射线二极管阵列可以很容易地探测到在等离子体内部形成的软X射线辐射扰动的锯齿振荡波形,根据观测到的锯齿振荡的某些特征可以定性地确定等离子体芯部的磁场位形。在托卡马克等离子体加热过程中,电子加热和电流穿透使得电流分布不断峰化、中心磁轴附近的安全因子下降,当中心安全因子q(O)<1时在q=1磁面附近形成磁岛,磁岛的增长     

托卡马克等离子体的自感计算

在各类磁约束聚变实验装置中,采用多种形式的特殊设计的磁场线圈,总的磁场位形 是由外部线圈中的电流与等离子体内部的电流共同形成的。在托卡马克装置中,等离子体内部电流对形成最终的位形起重要作用,但在实际运行中,各种电流分布不可能一步到位,需要通过调节各个线圈中电流以达到形成所需位形的目的。同时,要设法跟踪等离子体中     

磁驱动旋转电弧运动图像及弧电压脉动的实验研究

磁驱动旋转电弧产生扩散电弧等离子体过程中有许多有趣的物理现象。本文利用高速摄影技术研究了大气压条件下、非均匀磁场中、大尺度磁驱动旋转氩电弧的电弧结构；在一定的弧电流和外磁场条件下，电弧的平面形状表现为不断发展和增长的螺旋结构，电弧螺旋结构的破裂往往产生于阴极附近的等离子体射流。采用图像分析的方法计算了外部磁场作用下阳极斑点沿弧室内壁的移动频率，分析了磁驱动旋转电弧运动过程中的弧电压脉动现象。结合电弧图像分析和电弧电压脉动及其FFT分析得出：电弧电压的大幅波动与多层电弧螺旋结构破裂和重建相关，而电弧电压的小幅波动则是弧根小幅跳动引起电弧拉长和收缩的结果。     

STE—2反场箍缩极向偏滤器实验的首批结果

已在有一个外偏滤器室的放电容器中产生了有单极向零的反场箍缩。在目前的实验中没有装上导电壳。极向偏滤器位形维持的时间为壁的时间常数，在磁起伏中ｍ＝１撕裂模的优势不受偏滤器位形的影响。采用偏滤器位形和在偏滤器电流达到主等离子体电流的３０％的情况下，极向偏滤器都没有引起对等离子体性能的有害效应。     

诊断聚变等离子体的技术进展

为了安全运行，探索和优化聚变实验的性能以及详细研究等离子体物理，聚变研究主要依靠等离子体诊断，近几年，等离子体诊断技术取得了许多进展，这不仅是新的革新技术发展的结果，也是公认方法的改进和精心运用的结果。磁约束等离子体具有许多自由度，并受许多边界条件的影响，因此，了为完全表征聚变等离子体的特征，需要测量大量相应的等离子体参数，一些参数，如磁场、电流、温度和密度，有十分明显的要求。但有一些参数却更难捉     

阴极真空弧源磁过滤弯管偏压模式研究

为了改进阴极真空弧等离子体通过磁过滤弯管的传输效率，测定了磁过滤弯管出口离子电流与阴极弧流的关系，结果表明：磁过滤弯管内表面中，靠近大径中心一侧的表面（内侧面）和远离大径中心一侧的表面（外侧面）与等离子体的相互作用是独立的，存在两种向磁过滤弯等内表面运动的离子流：离子碰撞导致的横向扩散离子流和从阴极弧出来的较高能量的惯性离子流。两种离子流通过磁过滤管的传输过程有不同的机制。整个磁过滤弯管偏压较仅仅Bilek板偏压有更高的离子传输效率，Bilek板偏压对磁过滤弯管离子传输起主要作用。     

利用负磁剪切改善托卡马克中的等离子体性能

本文报道一种托卡马克等离子体位形，它在最大的稳定等离子体压强、自举电流贡献以及环形几何结构中温度和密度梯度驱动的模的动力学稳定性方面同时得到改善。其特点在于等离子体内部的负磁剪切和峰化压力分布。对理想低ｎ外部扭曲模的稳定性要求等离子体小半径的１．３倍处有一个导体壳。这种新颖的等离子体位形有希望改善先进托卡马克实验中的等离子体性能。     

SWIP-RFP装置等离子体环电压和电流测量

介绍SWIP-RFP装置等离子体环电压和环电流的测量方法和测量结果。对RFP环电压模型也作了初步分析,实验中采用单匝线圈测量的环电压很大程度地取决于外电路的电流,这一电压中存在一感应分量,即使考虑了测量环电压的感应分量,RFP等离子体的环电压也要大于环形磁约束系统等离子体的经典电阻环电压,这是反场箍缩等离子体螺旋量     

AC loss measurements on Cable in Conduit Conductor with random-changing magnetic fields

Beside the generation of the poloidal component of the field, the main function of the poloidal field coils in a tokamak is the control of the shape and the position of the plasma, according to the chosen plasma scenario. A plasma scenario, namely a sequence of plasma shapes, is obtained and controlled by varying the current in the PF coils. The control currents create magnetic fields having complex trends, being almost random waveforms with frequencies in the range between 0.1 and 10 Hz. As a consequence, AC loss is generated in the superconducting coils exposed to those signals, and the feasibility of a plasma scenario is strictly related to the ability to withstand and remove the heat coming from the AC loss.In order to study what the behavior of the loss is in random magnetic fields, namely similar to the control fields, a SULTAN sample is tested under two kinds of random field signals. The first signal is obtained by summing several harmonic frequency components, in the range between 0.2 and 6 Hz, having random amplitude. The second waveform is generated by a random function generator and it has a much broader spectrum of frequencies. The tests are carried out by varying also the maximum amplitude of the signals. The results are here discussed and compared to the results of the single frequency AC loss tests, and a correlation between them is studied.     

Study of the EAST Fast Control Power Supply Based on Carrier Phase-Shift PWM

EAST(experimental advanced superconducting tokamak) fast control power supply is a high-capacity single-phase AC/DC/AC inverter power supply,which traces the displacement signal of plasma,and excites coils in a vacuum vessel to produce a magnetic field that realizes plasma stabilization.To meet the requirements of a large current and fast response,the multiple structure of the carrier phase-shift three-level inverter is presented,which realizes parallelled multi-inverters,raises the equivalent switching frequency of the inverters and improves the performance of output waves.In this work the design scheme is analyzed,and the output harmonic characteristic of parallel inverters is studied.The simulation and experimental results confirm that the scheme and control strategy is valid.The power supply system can supply a large current,and has a perfect performance on harmonic features as well as the ability of a fast response.     

等离子体电流反向平衡位形中带电粒子运动的数值模拟研究

本文采用数值方法求解Grad-Shafranov方程获得CT-6B交流放电实验总电流过零时的平衡位形和磁场分布,进而结合粒子在磁场中的运动方程,模拟氘离子在该平衡位形中的运动轨迹,统计氘离子的损失率与损失位置。结果表明：总电流过零时刻的平衡位形为内外两侧电流反向平衡位形,在强、弱场侧各存在1个磁岛,电流在磁岛附近取极值;位于强场侧的粒子几乎不损失,弱场侧的粒子在径向位置很大时存在损失,越靠近边界损失率越高;损失位置基本上位于赤道面以下并在最底部达到极值;随初始角变大,氘离子轨迹由通行轨迹变成损失轨迹再向香蕉轨迹演变。     

AC Loss of ITER Feeder Busbar in 15MA Plasma Current Reference Scenario

Superconducting feeder busbar is a crucial component of the International Thermonuclear Experimental Reactor feeder system. AC losses including hysteresis loss and coupling-current losses (10 cycles and 1000 cycles) of the toroidal field feeder main busbar are described and calculated in detail in 15MA plasma current reference scenario in this paper. The critical current density is taken independent of magnetic field, and then the hystersis loss is evaluated; the calculated values of time constant of strands and sub-cables and the test values are approximate, and then the coupling losses are evaluted, too.     

Design of the power system for dynamic resonant magnetic perturbation coils on the J-TEXT tokamak

A set of in-vessel saddle coils has been installed on J-TEXT tokamak. They are proposed for further researches on controlling tearing modes and driving plasma rotation by static and dynamic resonant magnetic perturbations (RMPs). The saddle coils will be energized by DC with the amplitude up to 10 kA, or AC with maximum amplitude up to 5 kA within the frequency range of 1–5 kHz. At DC mode two antiparallel 6-pulse phase thyristor rectifiers are chosen to obtain bidirectional current, while at AC mode an AC–DC–AC converter including a series resonant inverter can generate current of various amplitudes and frequencies. The paper presents the design of the power supply system, based on the definition of the power supply requirements and the feasibility of implementation of the topology and control strategy. Some simulation and experimental results are given in the end.     

平行极板间等离子体RF共振特性研究

为探索用于ＡＶＬＩＳ的更为有效的离子引出方法,对等离子的ＲＦ共振离子出引方法进行了理论研究,用ＰＩＣ方法对其了模拟。结果表明：在弱磁场下可产生鞘层－等离子体振荡,其振荡频率与理论一致;外加与振荡频率王牟的交流电压后将发生共振,其振荡幅度大幅增加,电流加大,共振在等离子体中产生的最大电位幅可高于外加电压幅度几倍;与离子引出方法中传统的平行板电场相比,ＲＦ共振法使得出出的离子流加大,离子引出时间显著     

Measurements of plasma parameters in a hollow electrode AC glow discharge in helium

Measurements of the plasma parameters of coaxial gridded hollow electrode alternating current(AC)discharge helium plasma were carried out using an improved probe diagnostic technology.The measurements were performed under well-defined discharge conditions(chamber geometry,input power,AC power frequency,and external electrical characteristics).The problems encountered in describing the characteristics of AC discharge in many probe diagnostic methods were addressed by using an improved probe diagnostics design.This design can also be applied to the measurement of plasma parameters in many kinds of plasma sources in which the probe potential fluctuates with the discharge current.Several parameters of the hollow electrode AC helium discharge plasma were measured,including the plasma density,electron temperature,plasma density profiles,and changes in plasma density at different input power values and helium pressures.The characteristics of the coaxial gridded hollow electrode plasma determined by the experiments are suitable for comparison with plasma simulations,and for use in many applications of hollow cathode plasma.     

Characteristic Analysis of AC Plasma Arc in Water

An experimental system of AC arc discharge in water was designed with pole-pole electrodes and a peak voltage of 1500 V and a test circuit was set up using virtual instrument technology. The mechanism of an AC plasma arc generated in water was analyzed. The voltage- current characteristic of the AC plasma arc was obtained from the waveform. The temperature characteristic was tested with a spectrum diagnosis system, and the effect of different electrode materials on the striking voltage and peak current was analyzed. The results show that when a power supply of 6 KW is applied on electrodes with a gap of 2 mm in water, the striking voltage is from 900 to 1300 V, the arc voltage is from 40 to 100 V, the arc current is from 2 to 7 A, and the zero rest period is from 1 to 2 ms. In addition, the arc voltage and current are different for electrodes in aluminum, copper and stainless steel. The arc voltage is lower and the current is higher for an aluminum electrode than those for copper and stainless steel ones. The highest temperature of the arc is 7643 K.     

The Feasibility of Applying AC Driven Low-Temperature Plasma for Multi-Cycle Detonation Initiation

Ignition is a key system in pulse detonation engines(PDE). As advanced ignition methods, nanosecond pulse discharge low-temperature plasma ignition is used in some combustion systems, and continuous alternating current(AC) driven low-temperature plasma using dielectric barrier discharge(DBD) is used for the combustion assistant. However, continuous AC driven plasmas cannot be used for ignition in pulse detonation engines. In this paper, experimental and numerical studies of pneumatic valve PDE using an AC driven low-temperature plasma igniter were described. The pneumatic valve was jointly designed with the low-temperature plasma igniter,and the numerical simulation of the cold-state flow field in the pneumatic valve showed that a complex flow in the discharge area, along with low speed, was beneficial for successful ignition. In the experiments ethylene was used as the fuel and air as oxidizing agent, ignition by an AC driven low-temperature plasma achieved multi-cycle intermittent detonation combustion on a PDE, the working frequency of the PDE reached 15 Hz and the peak pressure of the detonation wave was approximately 2.0 MPa. The experimental verifications of the feasibility in PDE ignition expanded the application field of AC driven low-temperature plasma.     

Identification of Plasma Boundary and Position for HL-2A Tokamak

Using the virtual-case principle, the plasma boundary, the plasma current center, and the x-point are identified for the HL-2A tokamak. The plasma current is represented by the current center and the virtual multipole moments which produce a magnetic flux in a form of polynomial. Adaptive parameters in the polynomial are determined by the least-square fit of the poloidal magnetic fields. The measurement of the magnetic field is performed using pick-up coils. The virtual-case principle is applied outside the plasma boundary. The virtual-case currents decide the position of the current center and produce a negative confinement magnetic field inside the plasma and the magnetic field generated by the plasma current outside the plasma boundary. The convergence is fast enough to get a picture between the sequent shots. The configuration reconstructed is in good agreement with the TV image taken by camera with a tangential view.