HIRFL注入器高频腔体与高频机的匹配

 叙述了兰州重离子加速器注入器(SFC)高频系统的200 kW高频机与高频腔体的功率匹配，匹配测量系统的工作原理，以及对匹配系统的改进和完善，并对高频腔体的输入阻抗和耦合电容进行了计算。为提高高频系统的稳定性和可靠性，对影响高频功率传输和D电压提高的问题进行了深入的研究和改进。采用矢量阻抗仪冷态测量腔体匹配阻抗的方法和一些相应的技术和措施，用矢量电压表动态测量功率输出级的相位差，判断D电路是否工作在匹配状态，从而使SFC的D电压由原来的50~65 kV（不稳定）提高到稳定工作的105 kV，改善了SFC的工作状态和保证了SFC的高效运行。     

A prototype RF power source for CSNS/RCS

A prototype RF power source has been built to supply high RF power to a ferrite-loaded cavity, which is a part of R&D of the Rapid Cycling Synchrotron of China Spallation Neutron Source (CSNS/RCS). A direct fast RF feedback amplifier, a 4:1 impedance transformer and auto tuning grid were locally located to compensate the heavy beam loading of CSNS/RCS. Design and commissioning of the RF power source is discussed here, also with some advice on system improvement.     

合肥电子储存环上新旧高频腔的尾场及耦合阻抗的计算

 合肥800MeV电子储存环的二期升级工程正在进行，其中高频腔的改造和加工将要完成，由于原有高频腔存在较多不合理因数，将要被新腔所替换。为了充分估计在将来运行时，高频腔的耦合阻抗对储存高流强的影响，需要对新旧高频腔宽带耦合阻抗进行比较计算。用电磁场计算软件MAFIA对高频腔的耦合阻抗及电子束在此结构中产生的尾场进行了计算，结果说明旧高频腔的耦合阻抗比新高频腔小。     

Emittance measurement & optimization for the photocathode RF gun with laser profile shaping

The Laser Undulator Compact X-ray source(LUCX) is a test bench for a compact high brightness X-ray generator,based on inverse Compton Scattering at KEK,which requires high intensity multi-bunch trains with low transverse emittance.A photocathode RF gun with emittance compensation solenoid is used as an electron source.Much endeavor has been made to increase the beam intensity in the multi-bunch trains.The cavity of the RF gun is tuned into an unbalanced field in order to reduce space charge effects,so that the field gradient on the cathode surface is relatively higher when the forward RF power into gun cavity is not high enough.A laser profile shaper is employed to convert the driving laser profile from Gaussian into uniform.In this research we seek to find the optimized operational conditions for the decrease of the transverse emittance.With the uniform driving laser and the unbalanced RF gun,the RMS transverse emittance of a 1 nC bunch has been improved effectively from 5.46 πmm.mrad to 3.66 πmm.mrad.     

RF cavity for gas laser excitation

Summary A new technique for RF transverse excitation of gas laser has been tested: the plasma tube has been put inside a quarter wave strip line RF cavity. Excellent field uniformity and arcing problem avoidance have been observed. The efficiency is greater than 15%. The guidelines for cavity design are discussed. Work partially supported by ENEA-Contract No. C/451 (Dip. Fusione Associazione EURATOM-ENEA, CRE Frascati).     

Design and research of RF system for 10 MeV compact cyclotron

A 10 MeV compact cyclotron (CYCHU-10) has been developing in Huazhong University of Science and Technology (HUST). The RF system includes a 10 kW RF power generator and a resonance cavity. There is no automatic frequency tuning equipment in the cavity due to space limitations, so the generator must search and track the cavity resonant frequency. AD9850 synthesizer is used to generate RF signal in the experimental prototype, and a fine sinusoidal waveform around 99 MHz is obtained with the method of picking up a special aliased signal from the synthesizer’s output, and the output power level can be set by regulating the resistor connected to the Pin ‘R _set’. The final stage amplifier based on tetrode operates in the grounded cathode configuration, and the schematic of the tetrode circuit is illustrated. The method of searching the resonant frequency is discussed in detail. For the sake of a compact and robust structure, the resonance cavity will adopt non-uniform characteristic impedance coaxial structure, and the magnet surface electroplated with copper will be used as dummy Dees. The precise shapes and dimensions of the cavity are designed and simulation results are carried out in this paper. The distributions of electromagnetic field are illustrated by means of numerical calculation analysis, and the wooden model test is preformed as well.     

Digital prototype of LLRF system for SSRF

This paper describes a field programming gate array(FPGA)based low level radio frequency (LLRF)prototype for the SSRF storage ring RF system.This prototype includes the local oscillator(LO),analog front end,digital front end,RF out,clock distributing,digital signal processing and communication functions.All feedback algorithms are performed in FPGA.The long term of the test prototype with high power shows that the variations of the RF amplitude and the phase in the accelerating cavity are less than 1%and 1°respectively.and the variation of the cavity resonance frequency is controlled within ±10 Hz.     

光阴极RF腔注入器

 光阴极RF腔注入器是一种强流、窄脉冲(ps量级)、低发射度的电子束源。文章给出了CAEP光阴极RF腔注入器的结构和实验结果,结构主要包括驱动激光器、Cs₂Te阴极制备室、2.5个RF腔、高功率微波源和测量仪器等,其中驱动激光器的参数是影响注入器电子束质量的重要因素;实验上,该光阴极RF腔注入器可稳定输出能量2MeV、流强70A、发射度～4mm.mrad的高亮度电子束流。     

Single-lobed Near Diffraction-limited Beam from 1W Laser Diode Array with an External Cavity

1　Ｉｎｔｒｏｄｕｃｔｉｏｎ　　ＳｅｍｉｃｏｎｄｕｃｔｏｒｌａｓｅｒａｒｒａｙｓｈａｖｅｒｅａｃｈｅｄｈｉｇｈｏｕｔｐｕｔｐｏｗｅｒｏｆｓｅｖｅｒａｌＷｉｎｃｏｎｔｉｎｕｏｕｓ ｗａｖｅｏｐｅｒａｔｉｏｎ[1] ,ｂｕｔｄｕｅｔｏｔｈｅｐｏｏｒｓｐａｔｉａｌｃｏｈｅｒｅｎｃｅａｎｄｂｅａｍ ｐｒｏｆｉｌｅ ,ａｐｐｌｉｃａｔｉｏｎｓａｒｅｌｉｍｉｔｅｄ .Ｉｎｏｒｄｅｒｔｏｅｎｈａｎｃｅｔｈｅｓｐａｔｉａｌｃｏｈｅｒｅｎｃｅ,ｔｈｅｎｕｍｂｅｒｏｆｔｒａｎｓｖｅｒｓｅｍｏｄｅｓｍｕｓｔｂｅｒｅｄｕｃｅｄ ,ｗ…     

Single-lobed Near Diffraction-limited Beam from 1W Laser Diode Array with an External Cavity

Abstract　An external cavity for the laser diode array with a conventional mirror in what we call two-time self-injection operation is presented. The external cavity consists of two lenses, a flat external mirror(EM) in the image plane of the array and a prism that is used as an output coupler. The single-lobed near diffraction-limited far field beam of a 1 W 10-stripe gain-guided LD array lies at 6.4°～9° with the external cavity operation in two-time self-injection mode, whereas at 2.5°～3.0° for its normal feedback operation. The width of the far field beam (FWHM) is 0.43° and 0.63° at driving current of 2 and 3.2 ×Ithr, respectively, much narrower than that in normal feedback operation, but at the expense of lower output power. The output of the system is very stable and insensitive to the tilt and position of the EM.     

Power scaling of diffusion-cooled lasers

An excitation and optical extraction geometry suitable for compact high power gas lasers is described. Multiple slab discharges are established in a diffusion-cooled radial electrode array. Each gain channel is independently driven from a common RF source via a resonant-cavity power distribution system. Radial excitation augmented with multi-channel self-injection phase locking provides stable optical power extraction at good efficiency. The concept is easily scalable to very high powers while dramatically reducing unit size and cost.     

Travelling Modes in Wave-Heated Plasma Sources

This paper describes a theoretical and experimental study of surface- and helicon-wave-heated plasma sources in which standing waves are set up in the cavity between the closed end plate to a plasma vessel and a wave launcher while travelling waves propagate from the opposite side of the launcher into a region which is long compared with the attenuation distance of the waves. We model the situation as a lossy transmission line of finite length coupled at the launcher to a lossy transmission line of infinite extent. RF power applied to the launcher divides in the ratio of the input impedances of the two transmission lines. For a conducting end plate, the power delivered to the travelling waves is a maximum when the cavity length is an odd number of 1/4 wavelengths long for which its input impedance is a maximum. Similarly, for an insulated end plate, the power delivered to the travelling waves is a maximum for a cavity with a length equal to an integer number of half wavelengths for which its input impedance is again a maximum.      

SSC新高频腔设计与分析

简要分析了HIRFL SFC与SSC之间的束流匹配关系, 给出了新高频腔的频率范围。 利用经典三维电磁场数值模拟软件MAFIA对SSC新高频腔体进行了模拟计算, 得出了SSC新高频腔体的相关物理参数, 并对频率范围、Q值、 并联阻抗和电压分布等参数进行了分析。 高频腔体的模拟计算结果完全符合SSC回旋加速器改造的物理设计及空间结构要求。     

用于HIRFL-CSRm纵向压缩高频腔的磁合金环测试

在HIRFL-CSRm上进行高能量密度物理和等离子体物理的研究需要一个能提供高电压的高频腔来对束团进行纵向压缩, 而磁合金加载腔获得较高的加速场梯度可以满足这一要求, 且腔体不需要调谐, 从而简化了高频控制系统。为了选择磁导率和阻抗较大、Q值(品质因数)小于1的磁合金材料来加载压缩高频腔, 对型号为V和A的两种磁合金材料进行了测试。测试结果表明: 型号为V的材料具有较大的磁导率、 阻抗和小于1的Q值, 将被用来加载腔体以获得足够高的加速电场梯度。A high voltage RF cavity is required to compress the beam bunch in the longitudinal for high energy density physics and plasma physics research at HIRFL CSRm. A magnetic alloy (MA) loaded cavity which has high acceleration gradient and without tuning loop (can simplify the RF control system), can meet the requirement. In order to select a proper MA material with higher permeability and shunt impe dance, Q< 1 value to load the RF compression cavity, two different MA materials V and A have been tes ted. The results indicate that the material V will be better for the construction of the RF cavity than material A because of its higher permeability and shunt impedance, Q< 1 value.     

HIRFL高频腔体功率耦合匹配实验研究

 介绍了HIRFL主加速器SSC高频腔体功率馈入耦合匹配系统的研究，实验结果表明，通过改变耦合环角度可更好地实现高频腔体和高频发射机之间的匹配，提高了高频腔体电压和高频发射机的工作效率。     

RF generator for compact CO2 waveguide lasers

This letter reports the fabrication and testing of a compact Radio Frequency Generator (Oscillator-Amplifier) for its integration in a CO₂ waveguide laser. The circuit uses a common source MOSFET transistor that has been modified for self-sustained oscillations impedance-matched to 50 Ω. RF power is supplied to the laser resonant cavity made of a ceramic-metal slab which is placed between a negative branch unstable optical resonator.     

Study of RF Excited CO2 Waveguide Laser Array

RF excited CO2 waveguide laser arrays with three different structures (one-dimension and two-dimension) are reported in this paper. The output character of far-field and near-field of those lasers have studies and the phase locking between the waveguide elements has discussed. The cavity length of waveguide laser array is 380 mm and the resonator is formed by placing a plane germanium coated gold mirror and a plane ZnSe output coupler. The laser is operated with filling static gas of He∶N2∶CO2∶Xe=3∶1∶1∶0.1 mixture at 1.06×104 Pa total pressure. High output power density is achieved and the output power is 30-w with an efficiency η=10%. The output power is limited by the maximum power of RF transmitter.     

Study of RF Excited CO 2 Waveguide Laser Array

Ｉｎｔｒｏｄｕｃｔｉｏｎ　　ＴｈｅＲＦｅｘｃｉｔｅｄｔｅｃｈｎｉｑｕｅｔｏＣＯ２ｗａｖｅｇｕｉｄｅｌａｓｅｒｈａｓｂｅｅｎｒａｐｉｄｌｙｉｍｐｒｏｖｅｄ．ＭａｎｙｎｅｗｓｔｒｕｃｔｕｒｅｓｈａｓａｐｐｅａｒｅｄｓｉｎｃｅＫ．Ｄ．Ｌａａｋｍａｎ［１］ｍａｄｅｆｉｒｓｔｌｙｏｕｔｔｒａｎｓｖｅｒｓｅｅｘｃｉｔｅｄｗａｖｅｇｕｉｄｅＣＯ２ｌａｓｅｒｆｉｒｓｔｉｎ１９７７,ｓｕｃｈａｓｃｏｈｅｒｅｎｔｐｈａｓｅｌｏｃｋｅｄ１×２ａｒｒａｙＣＯ２ｗａｖｅｇｕｉｄｅｌａｓｅｒｇｉｖｅｎｂｙＤ．Ｇ．Ｙｏｕｍ…     

ǿ��RF ����Դ���Ƽ�����ʵ��

介绍了RF离子源驱动源的结构设计及RF线圈的热流固耦合分析。RF离子源采用外置天线的感应耦合方式,采用双射频驱动源设计,每个射频驱动源功率约60kW,总体功率为120kW,可产生均匀高密度的等离子体,以满足稳定的长脉冲运行的要求。在完成上述工作的基础上完成了RF离子源样机组装和初步实验测试。     

强流RF 离子源研制及初步实验

介绍了RF离子源驱动源的结构设计及RF线圈的热流固耦合分析。RF离子源采用外置天线的感应耦合方式,采用双射频驱动源设计,每个射频驱动源功率约60kW,总体功率为120kW,可产生均匀高密度的等离子体,以满足稳定的长脉冲运行的要求。在完成上述工作的基础上完成了RF离子源样机组装和初步实验测试。