For large-scale free-electron laser facilities based on linear accelerators, the laser saturation point is not frequently fixed in the undulator, which will cause a longitudinal source point drift of the beamline. The longitudinal source point drift will cause an instability in the performance of the beamline, especially affecting the energy-resolving power of variable-line-spacing grating monochromators for soft X-ray beamlines. A method of adjusting the fixed-focus constant to compensate for this longitudinal source point drift is introduced in this work. Simulation results indicate that this method can effectively recover the energy-resolving power of the grating monochromator.

The limited pattern area of periodic nanostructures limits the development of practical devices. This study introduces an X-ray interference lithography (XIL) stitching technique to fabricate a large-area (1.5 cm × 1.5 cm) two-dimensional photonic crystal (PhC) on the YAG: Ce scintillator, which functions as an encoder in a high numerical aperture optical encoding imaging system to effectively capture high-frequency information. An X-ray imaging experiment revealed a substantial 7.64 dB improvement in the signal-to-noise ratio (SNR) across a large field of view (2.6 mm × 2.6 mm) and achieved comparable or superior image quality with half the exposure dose. These findings have significant implications for advancing practical applications of X-ray imaging.

Due to the complex application scenarios of wire rope and the limited detection equipment, the detection results are not reliable and efficient, and the detection algorithm is difficult to deploy and transplant. Therefore, a lightweight model based on YOLOv7-tiny is proposed, and the Ghost convolutional module is introduced to achieve the lightweight network. ECA self-attention algorithm is added to the backbone network to enhance the ability of network representation. CARAFE upsampling operator is used to enhance feature extraction. WIOU loss function is used to further improve the detection accuracy. Experiments on wire rope defect data set show that its performance is better than the original YOLOv7-tiny model, with an average accuracy of 93.2%, an increase of 4.7%, a decrease of 47% in parameters and a decrease of 45% in model size. In addition, compared with other advanced network models, it also has better overall performance.

A low voltage (5 kV) W band klystron has been designed. The klystron is driven by a 5 kV and 0.4 A sheet beam. Compared with the resonant cavity used in low voltage pencil beam klystron, the resonant cavity in the sheet beam klystron has a higher coupling coefficient, which means a higher efficiency limit and shorter circuit length. The klystron can generate a peak output power of 141 W. The corresponding efficiency is 7.1%. The whole interaction circuit is composed of three multi-gap cavities.

An equivalent circuit analysis method for the Folded Waveguide (FW) slow-wave structure based on Multi-Sheet-Beam (MSB) is investigated. Folded waveguide is a periodic slow–wave structure made entirely of metal. It is commonly used in travelling wave tubes (TWT) due to its simple coupling structure, robust mechanical design, and excellent heat dissipation capabilities. The MSB-FW slow-wave structure utilizes multiple sheet beams to increase amplification power, reduce single beam current density, shorten the length of the electron beam channel, and improve efficiency. Thus, the MSB-FW slow-wave structure contributes to the performance of the TWT especially in THz band.The basic principle and working mechanism of the MSB-FW slow-wave structure are introduced firstly. Previous studies have been more detailed in the analysis of dual-pencil-beam or multi-pencil-beam. However, the analysis of Multi-Sheet-Beam has not yet been fully developed. Therefore, a method based on equivalent circuits to analyze the MSB-FW slow-wave structure is proposed. Based on microwave transmission line theory, the method has converted the MSB-FW slow-wave structure into equivalent microwave networks. Transmission line theory and microwave network analysis techniques are used for modelling and analysis. The equivalent circuit approach is used to analyze dispersion characteristics of MSB-FW slow-wave structure through rational selections of equivalent component parameters and topologies.The results indicate that the dispersion curves obtained from the theoretical results and the simulation results are consistent. This verifies the accuracy and reliability of the equivalent circuit analysis method and lays a foundation for the design of MSB-FW TWT.

As a unique coherent diffraction imaging method, X-ray ptychography has an ultrahigh resolution of several nanometers for extended samples. However, ptychography is often degraded by various noises that are mixed with diffracted signals on the detector. Some of the noises can transform into periodic artifacts (PAs) in reconstructed images, which is a basic problem in raster-scan ptychography. Herein, we propose a novel periodic-artifact suppressing algorithm (PASA) and present a new understanding of PAs or raster-grid pathology generation mechanisms, which include static intensity (SI) as an important cause of PAs. The PASA employs a gradient descent scheme to iteratively separate the SI pattern from original datasets and a probe support constraint applied in the object update. Both simulative and experimental data reconstructions demonstrated the effectiveness of the new algorithm in suppressing PAs and improving ptychography resolution and indicated a better performance of the PASA method in PA removal compared to other mainstream algorithms. In the meantime, we provided a complete description of SI conception and its key role in PA generation. The present work enhances the feasibility of raster-scan ptychography and could inspire new thoughts for dealing with various noises in ptychography.

An online automatic feedback system has been successfully installed and commissioned at the BL08U1A Soft X-ray Spectromicroscopy Beamline of Shanghai Synchrotron Radiation Facility, which can monitor the incident X-ray beam in real time by measuring the blade-edge signals of the exit slit and automatically adjust the elliptical cylindrical mirror parameters to achieve beam calibration and maintain the optimal X-ray flux of the sample. This work provides a comprehensive description of the hardware composition, system implementation, feedback logic, function and software design, system optimization and commission, as well as the online experimental results supported by the system. The experimental results demonstrated that the online automatic feedback system is capable of effectively maintaining the optimal X-ray beam flux for X-ray absorption spectroscopy experiments. Its success can provide valuable technique assistance for the design, construction and optimization of similar systems at various beamlines in synchrotron sources in the future.

随着计算机算力的提高与数学算法的不断突破,机器学习作为一种科学研究方法逐渐在化学工程中的过程优化、故障诊断等领域得到了应用,了解机器学习在化工中的研究进展对拓展化工领域的科研方法,改变传统的科研范式有较大意义.文章通过综述机器学习在萃取、精馏等单元操作中的应用场景及其使用的算法,归纳出化工数据用于机器学习的优势和劣势,提出采用机器学习模型对复杂多维非线性关系进行预测和对生产过程进行整体优化,是提高生产连续化和自动化水平的重要手段和方向.最后对机器学习应用于化工中其他领域(如计算流体力学、系统工程等)进行了展望.

介绍了一种应用于S波段同轴腔高功率多注速调管的电子枪设计方案.该电子枪总电子注数目为40个(内层19个,外层21个),工作电压为60 kV,总电流为300 A(平均分配在40个电子注上),单注导流系数为0.51 μP,总导流系数为20.4 μP,设计的阴极电流发射密度小于12 A/cm2,电子枪内最大场强为16.6 kV/mm.为使系统小型化,采用周期反转永磁聚焦系统约束电子注,聚焦系统由四组磁钢形成三个磁场均匀区,三个均匀区的磁场逐级增大,最小磁场强度为0.11 T,最大磁场强度为0.12 T.采用三维计算软件对电子注静电轨迹、磁场分布及聚焦轨迹进行了计算和优化,设计的多注电子枪电子注通过率达到了 100％.

质子加速器广泛应用于高能物理和肿瘤治疗领域,对作为其核心部件的低频段速调管的效率和尺寸有着较高的要求.为满足国内高性能质子加速器的需求,本文设计了一款小型化的P波段多注速调管.与传统单注速调管相比,多注速调管电压低、效率高、体积小.通过在群聚段引入高次谐波腔,可以进一步减小多注速调管的互作用长度,在实现小型化的同时达到高效率.本文介绍了 714 MHz、2 MW的脉冲波速调管的初步仿真与计算.利用一维仿真软件和三维仿真软件优化设计,得到了 74％的效率,增益为50 dB,互作用长度控制在1250 mm以内.

四极电子管可以作为射频四级场(radio frequency quadrupole,RFQ)加速器的射频功率源,而阴极和栅极作为四极电子管的关键电极,其结构参数直接影响四极电子管的输出功率和增益等主要性能参数.利用有限元分析软件ANSYS,对RF频率为195 MHz～600 MHz、输出功率为500 kW的四极电子管的栅极等关键部件进行了热分析计算.为模拟工作状态,首先施加阴极组件给定的功率,观测阴极和栅极组件的温度分布情况,然后进行抑制栅极散热翼片的结构优化与设计,仿真结果显示:栅极最高温度从289.29℃下降至268.21℃,达到优化抑制栅极的散热效果,并使用ANSYS的热-结构联合模块对其进行耦合计算分析,验证了优化后栅极结构的可行性,改善了四极管的散热需求,从而保证四极管能在合适的工作温度下稳定运行.

The efficiency of the RF power sources is one of the major concerns in the large-scale high-energy accelerator projects such as the future circular collider (FCC) and the compact linear collider (CLIC). The new bunching method, the core stabilization method (CSM), can achieve high efficiency in the case of shorter interactive length. The multibeam klystron (MBK) could accommodate high RF power with a low operating voltage, compared with a single-beam klystron. This article presents the design and simulation of a 650-MHz, 0.9-MW continuous wave (CW) CSM MBK. The detailed design of a six-beam optics system is also elaborated in this article. The performance of such a device was validated by the 3-D particle-in-cell (PIC)-code computer simulation. With an operating voltage of 50 kV, PIC simulation predicts an efficiency of 81.8%.

以工业级脉冲折流板萃取柱为研究对象,建立了液液两相流体C FD数学模型,利用C FD模型研究了分散相持液量、轴向扩散、湍流耗散率以及板间距对萃取柱的影响.结果表明:C FD模型预测的持液量与实验所测结果吻合良好,所建立的C FD模型有效,且C FD模型的持液量较经验公式预测结果更为准确.萃取柱轴向扩散系数随脉冲强度的增大而增大,在工程应用中脉冲强度不易过高.同时相比于分散相速度,连续相速度对轴向扩散系数的影响更大.利用CFD模型对Kummar提出的湍流耗散率经验公式常数进行了修正,常数修正为0.81,从而提高了计算结果的准确性.最后对比了不同板间距萃取柱水力学计算结果,发现萃取柱在工程设计时选取50 mm板间距更为合理.

A spurious-mode-suppression method is presented in this paper, which can increase the frequency interval between the operating mode (TM310 mode) and spurious mode (TM210 mode). With the numerical simulation, we find that the frequency interval can be increased from 0.321 GHz to 0.614 GHz in X-band. The simulation results were obtained by CST.

Gyroklystron operated in dual-band has profound research significance as a high-power microwave source, which can reduce the size, weight, and cost and contribute to the research of dual-band radar systems. In this paper, the theoretical analysis and simulation are used to design the output cavity operated in dual-band, the resonant frequency and quality factor of which are 9.34 GHz and 122 in X-band TE 011 mode, 16.8 GHz and 475 in Ku-band TE 021 mode respectively. It lays a foundation for the beam-wave interaction of the dual-band gyroklystron. Keywords: dual-band, output cavity, Gyroklystron

In this paper, a W-band multi-beam extended interaction klystron operating in the coaxial high order mode (HOM) is proposed. The HOM coaxial cavity with large transverse dimensions is suitable for accommodating multiple electron beams, promising to achieve high output power in the millimeter-wave frequency band. However, the operating method also brings lower characteristic impedance and a higher risk of mode competition. Based on the angular boundary condition of the coaxial HOM electric field, we propose a coaxial multi-gap cavity with a ridge structure to solve these problems. The TM51-2π mode is selected as the operating mode, of which the characteristic impedance can overwhelm that of the competing mode. The corresponding five-beam gun with a total current of 7 A (5 × 1.4 A) at a voltage of 25 kV is focused by a 0.65 T permanent magnet system. To demonstrate the capability of the device, the 3D particle-in-cell simulation predicts an output power of up to 30 kW at 94.4 GHz. The gain and electric efficiency are 54.8 dB and 17.2%, respectively.

High-power waveguide window is a critical component of high-power klystron and accelerator. The RF breakdown of the waveguide window always cause the failure of the high-power klystron. In this paper, the research progress of high-power waveguide window in the international vacuum electronics field is introduced. The research status, manufacturing requirement, and RF breakdown mechanism of the classical pill-box window are presented at first. Then the characters of some new type waveguide windows such as the tapered window, travelling wave in ceramic window, mixed-mode window, and over-mode window are summarized. Some breakdown suppression technologies like changing the material character of the window disk, changing the surface configuration of the window disk, using the positive dielectric angle, applying DC electric field or DC magnetic field, changing the waveform of transverse electric field are emphasized at the end.

近些年来,工业废酸的处理和回收逐渐成为困扰研究者的难题,膜分离技术以诸多优势成为研究重点.扩散渗析作为一种低能环保的膜分离技术,在废酸回收领域运用广泛,酸回收率一直是扩散渗析过程的重要指标.本工作以0.5～5mol/L盐酸为原料进行动态扩散渗析实验,考察进料酸浓度、进料流量(6～20mL/min)、水酸流量比(0.6～1.4)等操作参数对酸回收率的影响.通过无因次方法,针对特定的DF-120膜建立盐酸浓度和膜内渗透系数的经验公式,简化传质模拟,最终得到可以预测扩散渗析过程盐酸回收率的参数模型.对实验数据点进行分析,验证了数学模型的准确性.该模型也被用于更详细的实验操作条件下的预测,为实际工业生产提供了参考方法和理论依据.

In combination with ferromagnetic resonance and magnetic circular dichroism, the time-resolved X-ray ferromagnetic resonance method based on synchrotron radiation devices, which adopts the "pump-probe" technique of phase shift mode, is a unique technique to study a wide class of spintronics issues such as spin transfer torque and spin current. In this paper, an experimental apparatus that allows for the combination of the picosecond time-resolved technique and X-ray ferromagnetic resonance is introduced for the first time at the third-generation synchrotron radiation light source in China, Shanghai Synchrotron Radiation Facility. With this apparatus, the single-layer Permalloy (Ni81Fe19, Py) undergoes ferromagnetic resonance under the 2. 5 GHz microwave excitation and we measure the time-dependent projection of electronic spin precession cone angle of Ni in the Ni81Fe19 film in the beam direction. The results show that the apparatus can excite the electronic spin precession of magnetic elements on the magnitude of 2. 5 GHz and detect the amplitude and phase of electronic spin precession on the picosecond scale. This apparatus can provide unique technical support for the investigation into the spintronic materials and devices.

The MOI (mutual optical intensity) model is further developed and extended to analyze the mutual optical intensity propagation through a zone plate. This is the first study to quantitatively analyze the influence of the partial coherence property on the spatial resolution of zone plates. Increasing the source coherence length is beneficial for improving the spatial resolution of the zone plate; however, apparent diffraction peaks are observed at the focal plane. Reducing the sizes of the central stop and the order selecting aperture (OSA) can improve the signal-to-noise (SNR) ratio at the cost of the photon flux. Furthermore, we analyze the coherence property propagation through the STXM beamline at Shanghai Synchrotron Radiation Facility (SSRF), where a zone plate is used to focus the light into ∼30 nm. The coherence property increases and the photon flux decreases with decreasing exit slit size, which is beneficial for improving the spatial resolution of the zone plate. Therefore, the spatial resolution and flux can be balanced by optimizing the exit slit size.