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1.
Experimental confirmation of the linear rela-tion between plasma current and external vertical magnetic field in EXL-50 spherical torus energetic electron plasmas 
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下载免费PDF全文 《等离子体科学和技术》2024,26(8)
A three-fluid equilibrium plasma with bulk plasma and energetic electrons has been observed on the Xuanlong-50(EXL-50)spherical torus,where the energetic electrons play a crucial role in sustaining the plasma current and pressure.In this study,the equilibrium of a multi-fluid plasma was investigated by analyzing the relationship between the external vertical magnetic field(Bv),plasma current(Ip),the poloidal ratio(βp)and the Shafranov formula.Remarkably,our research demonstrates some validity of the Shafranov formula in the presence of multi-fluid plasma in EXL-50 spherical torus.This finding holds significant importance for future reactors as it allows for differentiation between alpha particles and background plasma.The study of multi-fluid plasma provides a significant reference value for the equilibrium reconstruction of burning plasma involving alpha particles. 相似文献
2.
A three-fluid equilibrium plasma with bulk plasma and energetic electrons has been observed on the Xuanlong-50 (EXL-50) spherical torus, where the energetic electrons play a crucial role in sustaining the plasma current and pressure. In this study, the equilibrium of a multi-fluid plasma was investigated by analyzing the relationship between the external vertical magnetic field (B V), plasma current (I p), the poloidal ratio (β p) and the Shafranov formula. Remarkably, our research demonstrates some validity of the Shafranov formula in the presence of multi-fluid plasma in EXL-50 spherical torus. This finding holds significant importance for future reactors as it allows for differentiation between alpha particles and background plasma. The study of multi-fluid plasma provides a significant reference value for the equilibrium reconstruction of burning plasma involving alpha particles. 相似文献
3.
In the Engineering Test Facility (ETF), the plasma pulse duration is expected to be hundreds of seconds, which is comparable to the resistive time scale that governs the resistive diffusion of the equilibrium. The resistive evolution of the safety factorq profile may, for MHD stability reasons, limit the duration of the plasma burn in a tokamak reactor. It may be possible to control this evolution and extend the plasma burn time through proper profile tailoring. We study the evolution of theq profile on the resistive time scale numerically using a one- and-one-half-dimensional (1 1/2-D) single fluid transport code. Two high beta (T 7–16%) cases are considered: (a) a beam-driven hydrogen plasma with no nuclear alpha heating for which the beam energy is used as a device to control the temperature profile, and (b) an ignited D-T plasma in which the neutral injection has been turned off. For the beam-driven plasma, it is shown that low beam energy heating profiles lead to resistive steady states having broad temperature profiles and flatq profiles, while high beam energy heating profiles lead to resistive steady states having peaked temperature profiles and deepq profiles. The centralized nuclear heating in an ignited D-T plasma causes the evolution of theq profile for this case to behave much like that in the high energy, beam-driven case: namely, theq values near the plasma center decrease on the resistive time scale until a deep, resistive, steady-stateq profile is reached.Research sponsored by the Office of Fusion Energy, U.S. Department of Energy, under contract W-7405-eng-26 with the Union Carbide Corporation. 相似文献
4.
Magnetohydrodynamic equilibrium schemes with toroidal plasma flows and scrape-off layer are developed for the 'divertor-type' and 'limiter-type' free boundaries in the tokamak cylindrical coordinate. With a toroidal plasma flow, the flux functions are considerably different under the isentropic and isothermal assumptions. The effects of the toroidal flow on the magnetic axis shift are investigated. In a high beta plasma, the magnetic shifts due to the toroidal flow are almost the same for both the isentropic and isothermal cases and are about 0.04a 0 (a 0 is the minor radius) for M 0=0.2 (the toroidal Alfvén Mach number on the magnetic axis). In addition, the X-point is slightly shifted upward by 0.0125a 0. But the magnetic axis and the X-point shift due to the toroidal flow may be neglected because M 0 is usually less than 0.05 in a real tokamak. The effects of the toroidal flow on the plasma parameters are also investigated. The high toroidal flow shifts the plasma outward due to the centrifugal effect. Temperature profiles are noticeable different because the plasma temperature is a flux function in the isothermal case. 相似文献
5.
The effect of the toroidal flow on the equilibrium of tokamak plasmas is a sensitive point for high performance plasma and its precise control. In this paper the effect is studied numerically using the EFIT （Equilibrium Fitting） code on EAST （Experimental Advanced Superconducting Tokamak）. Firstly, the numerical calculation exhibits a clear outward shift of pressure contour from the magnetic surfaces in the plasma core and the shift grows with the increase of the toroidal velocity. The peak shift of 8% is observed when the ratio between the plasma velocity and the Alfvdn speed equals to 0.15. Secondly, it is shown that the magnetic surfaces shift outwards from those without flow. With a certain plasma current the safety factor on the magnetic axis decreases as the plasma flow velocity increases. The magnetic shear increases about 10% on the plasma boundary compared with the case without flow. 相似文献
6.
Plasma equilibrium has been calculated using an analytical method. The plasma profiles of the current density, safety factor, pressure and magnetic surface function are obtained. The analytical solution of the Grad–Shafranov(GS) equation is obtained by the variable separation method and compared with the computed results of the equilibrium fitting code EFIT. 相似文献
7.
The method of plasma current profile reconstruction using the polarimeter/interferometer(POINT) data from a simulated equilibrium is explored and validated.It is shown that the safety factor(q) profile can be generally reconstructed from the external magnetic and POINT data.The reconstructed q profile is found to reasonably agree with the initial equilibriums.Comparisons of reconstructed q and density profiles using the magnetic data and the POINT data with 3%,5%and 10%random errors are investigated.The result shows that the POINT data could be used to a reasonably accurate determination of the q profile. 相似文献
8.
Dielectric barrier discharge (DBD) plasma actuators are widely used in active flow control due to their simple design and rapid responsiveness. However, they need more effectiveness and discharge extension. To overcome these limitations, a sector-shaped dielectric barrier discharge (SS-DBD) plasma actuator with an adjustable jet angle was developed to enhance flow control effectiveness. The flow field dynamics induced by the SS-DBD plasma actuator were quantitatively analyzed using particle image velocimetry (PIV). Experimental investigations showed that precise adjustments to the actuation voltage can modulate the maximum velocity of the induced jet. Furthermore, a quasi-linear relationship between the sector-shaped angles of the SS-DBD and the deflected jet angles was established, indicating that changes in the sector-shaped angles directly influence the direction of the deflected jet. This correlation enables precise control over jet angles, significantly enhancing flow control by adjusting the SS-DBD-PA’s sector-shaped angle. 相似文献
9.
Wenjin CHEN 《等离子体科学和技术》2022,24(3):35101
Magnetohydrodynamic equilibrium schemes with toroidal plasma flows and scrape-off layer are developed for the 'divertor-type' and 'limiter-type' free boundaries in the tokamak cylindrical coordinate. With a toroidal plasma flow, the flux functions are considerably different under the isentropic and isothermal assumptions. The effects of the toroidal flow on the magnetic axis shift are investigated. In a high beta plasma, the magnetic shifts due to the toroidal flow are almost the same for both the isentropic and isothermal cases and are about 0.04a0 (a0 is the minor radius) for M0 = 0.2 (the toroidal Alfvén Mach number on the magnetic axis). In addition, the X-point is slightly shifted upward by 0.0125a0. But the magnetic axis and the X-point shift due to the toroidal flow may be neglected because M0 is usually less than 0.05 in a real tokamak. The effects of the toroidal flow on the plasma parameters are also investigated. The high toroidal flow shifts the plasma outward due to the centrifugal effect. Temperature profiles are noticeable different because the plasma temperature is a flux function in the isothermal case. 相似文献
10.
In this work,a zero-dimensional plasma model for self-field magnetoplasmadynamic thrusters(SF-MPDTs) is proposed,which is based on the ion-number balance equation and energy balance equation,and can calculate the average electron temperature and the average ion temperature inside the discharge chamber conveniently.At the same time,the model can also predict the thruster performance,and the thruster performance predicted by the model is compared with experimental results,which proved the reliability of the model. 相似文献
11.
建立了由多种金属离子和小分子配体组成的多相人体血浆热力学平衡模型,并用该模型模拟研究了Pu4+在血浆中的形态分布及二乙三胺五乙酸(DTPA)和CO2-3、Citrate3-浓度对细胞液中Pu4+形态分布的影响。结果显示,血浆中的低浓度Pu4+易以Pu(OH)4(l)的形态蓄积在肝脏中,钚浓度升高则形成沉淀Pu(OH)4(s),难以排出体外。在DTPA浓度为2.5×10-5 mol/L时,血浆中水溶性小分子[Pu(OH)DTPA]2-含量达到最高并保持稳定。酸性条件下随着Citrate3-浓度的升高,血浆中Pu4+与Citrate3-结合形成可溶性的[PuCitrate2]2-和[PuCitrate]+的离子化合物。DTPA浓度大于4.6×10-5 mol/L时,血浆中的DTPA以与Ca2+、Mg2+结合形成的[CaHDTPA]2-、[Ca2DTPA]-、[CaDTPA]3-、[MgHDTPA]2-、[MgDTPA]3-小分子结合态为主。 相似文献
12.
LUO Bing 《等离子体科学和技术》2016,18(1):90-96
Radial equilibrium of the KTX plasma column is maintained by the vertical field which is produced by the equilibrium field coils.The equilibrium is also affected by the eddy current,which is generated by the coupling of copper shell,plasma and poloidal field coils.An equivalent circuit model is developed to analyze the dynamic performance of equilibrium field coils,without auxiliary power input to equilibrium field coils and passive conductors.Considering the coupling of poloidal field coils,copper shell and plasma,the evolution of spatial distribution of the eddy current density on the copper shell is estimated by finite element to analyze the effect of shell to balance.The simulation results show that the copper shell and equilibrium field coils can provide enough vertical field to balance 1 MA plasma current in phase 1 of a KTX discharge.Auxiliary power supply on the EQ coils is necessary to control the horizontal displacement of KTX due to the finite resistance effect of the shell. 相似文献
13.
Taifei ZHAO 《等离子体科学和技术》2022,24(11):114004
Plasma flow control technology has broad prospects for application. Compared with conventional dielectric barrier discharge plasma actuators (DBD-PA), the sliding discharge plasma actuator (SD-PA) has the advantages of a large discharge area and a deflectable induced jet. To achieve the basic performance requirements of light weight, low cost, and high reliability required for UAV (Unmanned Aerial Vehicle) plasma flight experiments, this work designed a microsecond pulse plasma supply that can be used for sliding discharge plasma actuators. In this study, the topology of the primary circuit of the microsecond pulse supply is determined, the waveform of the output terminal of the microsecond pulse plasma supply is detected using the Simulink simulation platform, and the design of the actuation voltage, the pulse frequency modulation function and the construction of the hardware circuit are achieved. Using electrical diagnosis and flow field analysis, the actuation characteristics and flow characteristics of sliding discharge plasma under microsecond pulse actuation are studied, the optimal electrical actuation parameters and flow field characteristics are described. 相似文献
14.
Controlling the poloidal field(PF) in the HT-7U superconducting tokamak is critical to the realization of the mission of advanced tokamak research.Plasma start-up,plasma position,shape,current control and plasma shape reconstruction have been performed as a part of its design process.The PF coils have been designed to produce a wide range of plasmas,Plasma start-up can be achieved for multiple conditions.Fast controlling coils for plasma position inside the vacuum vessel are sued for controloling the plasma vertical position on a short timescale.The PF coils control the plasma current and shape on a slower timescale,VXI(VME bus extensions for Instrumentation)Bus system and DSP(Digital Signal Processor is a basic unit of the feedback control system),the response time of which is about(2-4)ms.The basic unit of this system ,the shape-controlling algorithms of a few critical points on plasma boundary and real-time equilibrium fitting(RTEFIT)will be described in this paper. 相似文献
15.
Real-time equilibrium reconstruction is crucially important for plasma shape control in the process of tokamak plasma discharge.However,as the reconstruction algorithm is computationally intensive,it is very difficult to improve its accuracy and reduce the computation time,and some optimizations need to be done.This article describes the three most important aspects of this optimization:(1) compiler optimization;(2) some optimization for middle-scale matrix multiplication on the graphic processing unit and an algorithm which can solve the block tri-diagonal linear system efficiently in parallel;(3) a new algorithm to locate the XO point on the central processing unit.A static test proves the correctness and a dynamic test proves the feasibility of using the new code for real-time reconstruction with 129?×?129 grids;it can complete one iteration around 575 μs for each equilibrium reconstruction.The plasma displacements from real-time equilibrium reconstruction are compared with the experimental measurements,and the calculated results are consistent with the measured ones,which can be used as a reference for the real-time control of HL-2 A discharge. 相似文献
16.
The dispersion relation of standard geodesic acoustic modes in tokamak plasmas with anisotropic distribution and a radial equilibrium electric field is derived and analyzed. Both frequencies and damping rates increase with respect to the poloidal Mach number which indicates the strength of the radial electric field. The strength of anisotropy is denoted by the ratio of the parallel temperature(T_‖) to the perpendicular temperature(T_⊥). It is shown that, when the parallel temperature is lower than the perpendicular temperature, the enhanced anisotropy tends to enlarge the real frequency but reduces the damping rate, and when the parallel temperature is higher than the perpendicular temperature, the effect is opposite. The radial equilibrium electric field has stronger effect on the frequency and damping rate for the case with higher parallel temperature than the case with higher perpendicular temperature. 相似文献
17.
The EAST (HT-7U) superconducting tokamak is a national project of China on fusion research, with a capability of long-pulse (∽1000 s) operation. In order to realize a longduration steady-state operation of EAST,some significant capability of real-time control is required. It would be very crucial to obtain the current profile parameters and the plasma shapes in real time by a flexible control system. As those discharge parameters cannot be directly measured,so a current profile consistent with the magnetohydrodynamic equilibrium should be evaluatedfrom external magnetic measurements, based on a linearized iterative least square method, which can meet the requirements of the measurements. The arithmetic that the EFIT (equilibrium fitting code) is used for reference will be given in this paper and the computational efforts are reduced by parametrizing the current profile linearly in terms of a number of physical parameters.In order to introduce this reconstruction algorithm clearly,the main hardware design will be listed also. 相似文献
18.
The primary issue regarding the plasma synthetic jet actuator (PSJA) is its performance attenuation at high frequencies. To solve this issue, a self-supplementing, dual-cavity, plasma synthetic jet actuator (SD-PSJA) is designed, and the static properties of the SD-PSJA are investigated through experiments and numerical simulations. The pressure measurement shows that the SD-PSJA has two saturation frequencies (1200 Hz and 2100 Hz), and the experimental results show that both the saturation frequencies decrease as the volume of the bottom cavity of the SD-PSJA increases. As the size of the supplement hole increases, the first saturation frequency increases continuously, while the second saturation frequency shows a trend of first decreasing and then increasing. Numerical simulations show that the working process of the SD-PSJA is similar to that of the PSJA, but the volume of the cavity in the SD-PSJA is smaller than that of the PSJA; the SD-PSJA can supplement air to the top cavity through two holes, thus reducing the refresh time and effectively improving the jet intensity of the actuator at high frequencies. 相似文献
19.
研究了29例病人注射~(131)I—OIH后10—90min内获取6份血浆标本作清除曲线,用双室模型分析计算出ERPF作为参考标准。单份49min样本代替完整清除曲线所得结果的标准估计误差(Sy-x)为65.6ml/min,而两样本法(10和90min)的Sy·x可减小到20.7ml/min。 相似文献