The Chinese Heliac One (CN-H1) is planned to employ two electron cyclotron resonance heating (ECRH) systems operating at 2.45 GHz and 28 GHz for plasma start-up and heating, with a maximum designed magnetic field of 1 T. The ray-tracing code TRAVIS is employed to evaluate the power absorption efficiency of the 28 GHz fundamental-frequency ordinary (O1) and extraordinary (X1) modes in CN-H1 plasma. During the low-density, low-temperature start-up phase, the single pass absorption of the O1 mode across the resonance layer is weak, with the absorption efficiency not exceeding 20

The magnetic field configuration of the CN-H1 stellarator exhibits non-axisymmetric characteristics, which significantly affect the propagation and absorption of electromagnetic waves. Therefore, the wave launch position plays a crucial role in determining the effect of ion cyclotron resonance heating (ICRH). This paper utilizes the three-dimensional full-wave code to simulate ICRH with different wave launch positions on CN-H1. Employing the He-4 (H) minority ion heating scheme, it explores the impacts of the wave launch position [poloidal position, toroidal position as well as low-field side (LFS) and high-field side (HFS)] on ICRH. Our study suggests that the wave launch position in the toroidal direction should aim to maximize the length of the ion cyclotron resonance layer (ICRL) at the magnetic axis directly opposite the ion cyclotron range of frequency antenna. In the poloidal direction, the wave launch position should be placed as close as possible to the ICRL at the target heating position. Ion absorption in the target region requires the fulfillment of multiple conditions, and electron absorption exhibited favorable absorption characteristics across several simulated wave launch positions, particularly at the toroidal 0 degrees position, where excellent core electron absorption was observed. Due to reduced collisional damping, better wave penetration, and more favorable wave accessibility on the LFS under current device conditions, the heating effect on the LFS is superior to that on the HFS.

The relocation of the Australian H-1 National Facility (H-1 NF) to China and its reconstruction into the CN-H1 device necessitated a rigorous reassessment of its magnetic configuration to address systematic deviations introduced during the engineering process.This paper presents a comprehensive comparative study of the magnetic equilibrium across three distinct definitions of the device: the idealized H-1 Design, the historically built as-built H-1 NF, and the newly reconstructed CN-H1. High-precision laser tracker metrology was employed to generate a high-fidelity coil model for CN-H1, incorporating the remanufactured poloidal and helical windings. Calculations of the vacuum magnetic field reveal that, compared to the H-1 NF, the CN-H1 exhibits a systematic inward radial shift of the magnetic axis, a slight increase in the rotational transform, while maintaining a comparable level of stellarator symmetry breaking. Three-dimensional MHD equilibria were reconstructed using the VMEC code and validated against field-line tracing. To streamline this process, a new open-source pipeline, coils2vmec , was developed to automatically generate robust VMEC input files directly from coil geometry inputs. Comparative analysis across representative configurations demonstrates that the defining characteristics of the flexible heliac—including high rotational transform, shear tunability, and magnetic well depth—are preserved in CN-H1. Magnetic spectra in Boozer coordinates of CN-H1 are nearly indistinguishable from the H-1 NF historically built baseline, despite coilpositioning errors in the millimeter range. These results validate the engineering fidelity of the CN-H1 reconstruction and establish a precise equilibrium basis for future finite-beta plasma experiments.

Plasma rotation and its shear are key parameters influencing the performance of fusion devices. The prediction and control of plasma rotation velocity are of great significance for improving the stable operation and confinement of future fusion reactors. External momentum injection methods are insufficient to suppress resistive wall mode instability while achieving Q greater than 5 in international thermonuclear experimental reactor (ITER). Therefore, it is necessary to conduct experimental research on intrinsic plasma rotation that does not rely on external momentum injection. To better predict the magnitude of intrinsic rotation velocity in future fusion devices, we conduct an experimental study on the scaling of residual stress and dimensionless parameters on EAST. Using the balanced neutral beam, multiple measurements of intrinsic torque are performed, providing experimental basis for predicting the intrinsic rotation in future tokamak devices. The scaling results indicate that the core residual stress is dependent on rho(-1.80 +/- 1.26)(& lowast;), while the scaling of edge residual stress shows an opposite trend with rho(1.26 +/- 0.63)(& lowast;). This suggests that as the device size increases, the core residual stress in future large devices can increase, while the edge residual stress can decrease. The difference in scaling results between the core and edge residual stress indicates that in the edge region, the symmetry-breaking mechanism other than ExB flow shear dominates the generation of residual stress in the scrape-off layer. A relationship is found between intrinsic torque and nu(& lowast;), revealing that the core intrinsic torque depends on nu(-0.21 +/- 0.18)(& lowast;). Combining the scaling results of core intrinsic torque with the gyroradius and normalized collisionality, the scaling law for core intrinsic torque is obtained to be rho(-1.39 +/- 0.71)& lowast;( )nu(0.11 +/- 0.10)(& lowast;). Using plasma parameters of ITER operation scenario 1, the core intrinsic torque in future ITER plasma is predicted to be (1.0 +/- 6.3) N & sdot;m, which is much smaller than the predicted magnitude at DIII-D.

Plasma rotation and its shear are key parameters influencing fusion devices. The prediction and control of plasma rotation velocity are of great significance for the stable operation and confinement improvement of future fusion reactors. External momentum injection methods are insuffcient to suppress resistive wall mode instability while achieving Q greater than 5 in International Thermonuclear Experimental Reactor (ITER). Therefore, it is necessary to conduct experimental research on intrinsic plasma rotation that does not rely on external momentum injection.To better predict the magnitude of intrinsic rotation velocity in future fusion devices, this experiment conducted a study on the scaling of residual stress and dimensionless parameters on EAST. Using the balanced neutral beam, multiple measurements of intrinsic torque were performed, providing experimental basis for the prediction of intrinsic rotation in future tokamak devices. The scaling results indicate that the core residual stress has a dependency on $\rho_*^{-1.80 \pm 1.26}$, while the scaling of edge residual stress shown a opposite trend with $\rho_*^{1.26} \pm 0.63$.This suggests that as the device size increases, the core residual stress in future large devices may increase, while the edge residual stress may decrease. The difference in scaling results between the core and edge residual stress indicates that in the edge region, there are symmetry-breaking mechanisms other than E × B flow shear dominating the generation of residual stress in the scrape-off layer (SOL).A relationship was found between intrinsic torque and $\nu_*$, revealing that core intrinsic torque depends on $\nu_*^{-0.21 \pm 0.18}$.Combining the scaling results of core intrinsic torque with gyroradius and normalized collisionality, the scaling law for core intrinsic torque is obtained as $\rho_*^{-1.39 \pm 0.71} \nu_*^{0.11 \pm 0.10}$.Using plasma parameters of ITER operation scenario 1, the core intrinsic torque in future ITER plasma is predicted to be 1.0 ±6.3 N · m, which is much smaller than predicted magnitude at DIII-D.

Neutral Beam Injection(NBI)is an important auxiliary heating and driving method for Tokamak devices.The ionization of neutral atoms determines the neutral beam heating(energy and particle deposition profile)andcurrent drive efficiency.In general,the attenuation characteristics of the neutral beam are simulated by using the background plasma parameters and neutral beam parameters,and then the heating and current driving effects of the Tokamak neutral beam are analyzed.Beam emission spectroscopy is a series of characteristic spectral lines radiated by the excitation and deexcitation process of electron and ion collision of neutral beam-injected plasma.The strength of Beam emission spectroscopy is affected by plasma density,temperature,energy beam,beam density and other factors,so neutral beam attenuation can be acquired using the beam emission spectrum.This paper analyses neutral beam attenuation under different plasma densities and different neutral beam energies on EAST.Comparing the experimental and Simulation of Spectra(SOS)results,the experimental and simulation results are in good agreement.The feasibility of obtaining neutral beam attenuation characteristics by measuring the Beam emission spectroscopy is verified.

Abstract In this paper, we employ gauge/gravity duality to investigate the string breaking and melting of doubly-heavy tetraquark that includes two heavy quarks and two light antiquarks in a holographic model at finite temperature. Firstly, four different configurations of $${{\textrm{QQ}}}\bar{{\textrm{q}}}\bar{{\textrm{q}}}$$ QQ q ¯ q ¯ are studied at different separation distances of the heavy quarks at finite temperatures. At high temperature, $${{\textrm{QQ}}}\bar{{\textrm{q}}}\bar{{\textrm{q}}}$$ QQ q ¯ q ¯ will melt at certain distances and the screening distance has been given for different temperatures. As the temperature continues to increase, some configurations of doubly-heavy tetraquark can not exist. Furthermore, we investigate three decay modes of $${{\textrm{QQ}}}\bar{{\textrm{q}}}\bar{{\textrm{q}}}$$ QQ q ¯ q ¯ and compare the potential energy of $${{\textrm{QQ}}}\bar{{\textrm{q}}}\bar{{\textrm{q}}}$$ QQ q ¯ q ¯ with that of $${\textrm{QQq}}$$ QQq at finite temperature.

Theoretical investigations are conducted to examine the impact of toroidal rotation and ion collisional viscosity on low-frequency zonal flow (LFZF) in a tokamak plasma with the fluid model. The results indicate that while the frequency of LFZF remains unchanged during an isothermal process with γ = 1 , its damping rate is influenced by both toroidal rotation and ion collisional viscosity. Specifically, as the ion collisional viscosity increases, so does the damping rate of LFZF; conversely, as the toroidal rotation As its Mach number rises, its damping rate decreases. For a non-isothermal process with γ > 1 (such as γ = 5/3 ), the damping rate and frequency of LFZF are influenced by both toroidal rotation and ion collisional viscosity. It has been demonstrated that when the toroidal rotation Mach number surpasses a certain threshold, the frequency transitions from zero to a finite value, while the damping rate decreases as the toroidal rotation Mach number increases for LFZF. Furthermore, it has been observed that the damping rate of LFZF increases while the frequency decreases with an increase in ion collisional viscosity. Moreover, when the ion collisional viscosity surpasses a certain threshold, the frequency of LFZF drops to zero.

利用程序ORBIT和TRANSP/NUBEAM模拟研究全超导托卡马克实验装置(EAST)等离子体位形和杂质的特征参数Zeff(有效电荷数)对束离子约束和加热的影响.结果表明:在等离子体位形中,随着最后一个封闭通量表面与中面外容器壁之间的距离(gapout)和环向磁场强度的增加,快离子的损失(包含瞬时损失和波纹损失)也随之减少,因此中性束的加热效率随着gapout的增加而提高.此外,随着背景等离子体杂质的增加(即Zeff 的增加),增加了束损失,导致最后束加热效率降低.选择合适的磁位形,同时降低背景的杂质含量可以增强快离子约束,提高束的加热效率.

The eigen equation of pitch-angle distribution derived from the slowing-down distribution equation with an energetic particle source term is solved by using the Legendre series expansion method. An iteration matrix is established when pitch-angle scattering terms become important. The whole pitch-angle region is separated into three parts, two passing regions, and one trapped area. The slowing-down distribution for each region is finally obtained. The method is applied to solve the slowing-down equations with source terms that the pitch-angle distribution is Maxwellian-like, neutral beam injection, and radial drifts. The distribution functions are convergent for each source with different pitch-angle distribution. The method is suitable for solving a kinetic equation that pitch-angle scattering collision is important.

In this work, the effect of a magnetic island on Alfvén waves is studied. A physical model is established wherein Alfvén waves propagate in the presence of a magnetic island in a cylindrical geometry. The structure of the Alfvén wave continuum is calculated by considering only the coupling caused by the periodicity in the helical angle of the magnetic island. The results show that the magnetic island can induce an upshift in the Alfvén continuum. Moreover, the coupling between different branches of the continuous spectrum becomes more significant with increasing continuum mode numbers near the boundary of the magnetic island.

The cultivation of fusion graduate student innovation ability is of great significance to the development of magnetic confinement fusion energy in our country. This paper briefly analyzes the factors that affect the cultivation of innovation ability of nuclear fusion graduate students from the aspects of individual factors, tutor factors,school factors and so on, and puts forward some measures to cultivate the innovation ability of graduate students,such as "pay attention to basic theories, carry out fusion characteristic teaching", "share resources and conditions,strengthen academic exchange activities", "inherit characteristic culture, and strengthen the sense of responsibility and innovation". Some results have been achieved in practice.

The influence of two driven currents simultaneously and respectively imposed on the m/n = 2/1 and 3/2 resistive tearing modes in tokamak plasmas is researched by using a three-dimensional toroidal magnetohydrodynamic code CLT. The simulation results show that using two suitable driven currents can better suppress multiple tearing modes than using only one of the two driven currents. When the two suitable driven currents are simultaneously imposed on both the m/n = 2/1 and 3/2 modes, respectively, the two modes may be well suppressed. If only one of the driven currents is imposed on the m/n = 2/1 mode, then the m/n = 2/1 mode may be well suppressed but the m/n = 3/2 mode may be not. Conversely, if only the other of the two driven currents is imposed on the m/n = 3/2 mode, both the two modes may be not suppressed. Moreover, it should be noted that the parameters of using two driven currents to suppress multiple tearing modes must be appropriate; otherwise, some new modes (such as m/n = 5/3 mode) may be excited and grown due to the interaction among the driven currents and multiple modes.

该文从本科生视角出发以学生学习时间管理和教师对教学的时间投入为重点剖析当前本科教育存在的问题,主要体现为时间管理不当、沉迷于游戏等娱乐、与学业无关的院校级活动太多、学生熬夜现象盛行,针对这些问题从教育理念、学校管理制度改革、学生和教师减负等方面提出可行的解决方案.该科教学需要落实以学生为中心的教育方针,提倡以兴趣为驱动的个性化教学,调整教师教学和科研的评价体系,以"新工科"和新产业导向来改革现有的本科教学,提高本科生学习能力和教学质量.

In this paper, we present numerical simulation results that indicate that under certain conditions, a double-saddle antenna can excite helicon modes that resonate with the driving frequency in a nonuniform toroidal plasma, and m=1 and m=2 resonant standing helicon waves can separate or coexist in the toroidal plasma. The power absorption associated with the resonant standing wave is much larger than the power absorption associated with the nonresonant eigenmodes and accounts for most of the RF power deposited into the plasma. By adjusting the antenna frequency and wavenumber kz, the wave field structure, such as the standing wave pattern, the partially travelling-partially standing wave structure and the standing wave structure with amplitude modulation, can be controlled, which means that one can possibly control the resonant power absorption through careful antenna geometry and frequency design.

The enhanced transport of trapped energetic ions (TEIs) in the presence of resonant interactions between trapped fast ions and a rotating magnetic island is investigated within a drift-kinetic framework. Gyro-orbit banana center model equations of resonances between the island rotation, the bounce motion of trapped fast ions, and their precession frequency (poloidal precession and precession in the helical direction) are constructed. There are two solutions for resonances in phase space for different mode numbers, with only one solution having low-energy resonant lines (<100 keV); the other has not only low-energy resonant lines but also high-energy lines (≥100 keV). Island rotation plays an important role in the low-energy region, especially near the trapped-passing boundary. The precession frequency is more important when resonances occur in the high-energy area. Thus, the effect of islands on TEI transport in a low-energy region is the focus of this paper. Transport fluxes caused by collisions, resonances, and symmetry breaking induced by an island are obtained. We divide transport fluxes into two types: Γc arising from magnetic drift and Γb arising from the island rotation. There is a discontinuity in Γc with different island widths near the island separatrix. On the right-hand side of the (m = 2, n = 1) rational surface, Γc is more important than Γb, and at the plasma boundary, the flux due to drift can suppress Γb, which makes fast ions move toward inner plasma. On the left-hand side of the rational surface, Γb is dominant. When the island width is larger than a certain threshold, the fluxes oscillate, and Γb is far larger than Γc.

In this work, based on the liquid-drop model and considering the shell correction, we propose a simple formula to calculate the released energy of proton radioactivity（Q p ）. The parameters of this formula are obtained by fitting the experimental data of 29 nuclei with proton radioactivity from ground state. The standard deviation between the theoretical values and experimental ones is only 0.157 Me V. In addition, we extend this formula to calculate 51 proton radioactivity candidates in region 51≤Z≤83 taken from the latest evaluated atomic mass table AME2016 and compared with the Q p calculated by WS4 and HFB-29. The calculated results indicate that the evaluation ability of this formula for Q p is inferior to WS4 while better than HFB-29.

采用有限元法数值求解Maxwell方程组,分析H-1仿星器实验参数下螺旋天线的轴向长度对螺旋波传播、吸收的影响.计算结果表明:随着螺旋天线轴向长度的增加,天线总辐射能量和辐射电阻逐渐增大;在H-1等离子体中螺旋天线主要激发m=±1模式波,其中m=-1模式波一般在等离子体边界传播;全波螺旋激发的波能量主要沉积在等离子体边界,导致等离子体径向能量较强的非均匀吸收,加热效果不理想;半波螺旋天线激发的波可深入主等离子体区域传播,等离子体径向能量吸收相对均匀,加热效果好.

为了解决二维磁场位形的局限性,对三维磁场位形的研究势在必行.基于J-TEXT平衡参数,利用VMEC程序求解得到J-TEXT装置的三维磁场位形.此外,分析了等离子体电流、压强对磁场位形的影响,论证了VMEC程序应用在J-TEXT上的可行性.结果表明,VMEC程序能够初步满足J-TEXT装置的三维磁场位形研究要求,为后续装置三维磁场位形优化提供理论和工程借鉴意义.通过比较不同的等离子体电流,压强剖面对三维磁场的计算结果,表明了等离子体电流能够改变极向磁场强度,增大压强剖面使等离子体环状膨胀,磁轴外移.

本文分析了H-1NF仿星器的磁场线圈组成与分布特征,研究了其在标准运行模式下的磁场位形特点,并模拟计算出高能量离子在该标准磁场位形中的典型运动轨道.基于H-1NF仿星器标准磁场位形的磁轴位置和磁面沿环向角的变化规律,以磁轴为旋转轴,按照旋转规律将不同环向角的极向截面旋转后得到一种旋转坐标系下的等效标定极向截面,并将高能量离子的三维运动轨道投影到这种等效标定极向截面上,从而可更加清晰地显示出高能量离子在该磁场位形中的运动轨道特征.结果 表明,H-1NF仿星器中的通行粒子和捕获粒子轨道特征均与一般托卡马克中的相应粒子轨道特征相似,但H-1NF仿星器中的通行粒子轨道在等效标定极向截面上绕几圈后才闭合,H-1NF仿星器中捕获粒子的香蕉轨道没有闭合,且轨道逐渐向磁面外侧漂移,最终可能导致粒子损失.