硼中子俘获治疗实验装置射频功率源系统

中国科学院高能物理研究所建造了一台基于加速器的硼中子俘获治疗（BNCT）实验装置。射频功率源系统为352.2 MHz射频四极加速器（RFQ）提供高频功率,使束流离开RFQ时,其能量达到3.5 MeV。BNCT射频功率源系统主要包括速调管功率源、数字低电平控制系统、射频传输系统。本文介绍了BNCT射频功率源系统,主要包括物理需求、系统组成、关键设备、安装和调试。目前该装置已进行动物实验,加速器打靶束流功率4.3 kW,加速器射频功率源系统运行稳定。     

Experimental results of helicon sources

Helicon plasma sources are known as efficient generators of uniform and high density plasma.A helicon plasma source was developed for the investigation of plasma stripping and plasma lenses at the Institute of Modern Physics, CAS.In this paper, the characteristics of helicon plasma have been studied by using a Langmuir four-probe and a high plasma density up to 3.9×10~(13)/cm~3 has been achieved with the Nagoya type Ⅲ antenna.In the experiment, several important phenomena were found: (1) for a given magnetic induction intensity, the plasma density became greater with the increase of RF power; (2) helicon mode appeared at RF power between 300 W and 400 W; (3) the plasma density gradually tended to saturation as the RF power increased to the higher power; (4) a higher plasma density can be obtained by a good match between the RF power and the magnetic field distribution.The key issue is how to optimize the matching between the RF power and the magnetic field.Moreover, some tests on the extraction of ion beams were performed, and preliminary results are given.The problems which existed in the helicon ion source will be discussed and the increase in beam density will be expected by extraction system optimum.     

Collective effects for long bunches in dual harmonic RF systems

The storage of long bunches for large time intervals needs flattened stationary buckets with a large bucket height. Collective effects from the space charge and resistive impedance are studied by looking at the incoherent particle motion for the matched and mismatched bunches. Increasing the RF amplitude with particle number provides r.m.s wise matching for modest intensities. The incoherent motion of large amplitude particles depends on the details of the RF system. The resulting debunching process is a combination of the too small full RF acceptance together with the mismatch, enhanced by the collective effects. Irregular single particle motion is not associated with the coherent dipole instability. For the stationary phase space distribution of the Hofmann-Pedersen approach and for the dual harmonic RF system, stability limits are presented, which are too low if using realistic input distributions. For single and dual harmonic RF system with $d$=0.31, the tracking results are shown for intensities, by a factor of 3 above the threshold values. Small resistive impedances lead to coherent oscillations around the equilibrium phase value, as energy loss by resistive impedance is compensated by the energy gain of the RF system.     

Collective effects for long bunches in dual harmonic RF systems

The storage of long bunches for large time intervals needs flattened stationary buckets with a large bucket height.Collective effects from the space charge and resistive impedance are studied by looking at the incoherent particle motion for the matched and mismatched bunches.Increasing the RF amplitude with particle number provides r.m.s wise matching for modest intensities.The incoherent motion of large amplitude particles depends on the details of the RF system.The resulting debunching process is a combination of the too small full RF acceptance together with the mismatch,enhanced by the collective effects.Irregular single particle motion is not associated with the coherent dipole instability.For the stationary phase space distribution of the Hofmann-Pedersen approach and for the dual harmonic RF system,stability limits are presented,which are too low if using realistic input distributions.For single and dual harmonic RF system with d＝0.31,the tracking results are shown for intensities,by a factor of 3 above the threshold values.Small resistive impedances lead to coherent oscillations around the equilibrium phase value,as energy loss by resistive impedance is compensated by the energy gain of the RF system.     

射频场照射下同核体系的弛豫

根据WBR理论和同核体系的特点,构造出了一个相应的三维转动,利用Wigner旋转矩阵的特性并借助于计算机代数语言,计算出了射频场照射下同核体系完整的弛豫方程组.在此基础上,给出了射频场照射下纵向与横向弛豫时间的计算公式,并从理论上研究了射频场的照射对同核体系弛豫的影响.研究结果表明:1)射频场的照射对同核体系的弛豫有一定程度的影响.2)在射频场的照射下,同核体系的纵向弛豫时间T1小于无射频场时的T1,而横向弛豫时间T2大于无射频场时的T2.3)纵向弛豫时间T1随射频场的增强而逐渐减小,横向弛豫时间T2随射频场的增强而逐渐增大. 关键词： 核磁共振 弛豫 射频场 三维转动     

RF system design and measurement of HIRF-CSRe

An RF system for the CSRe （cooling storage experimental ring） is designed and manufactured domestically. The present paper mainly describes the RF system design in five main sections： ferrite ring, RF cavity, RF generator, low level system and cavity cooling. The cavity is based on a type of coaxial resonator which is shorted at the end with one gap and loaded with domestic ferrite rings. The RF generator is designed in the push-pull mode and the low level control system is based on a DSP＋FGPA＋DDS＋USB interface and has three feedback loops. Finally we give the results of the measurement on our system.     

HIRFL-CSR主环加速腔系统设计

正在建设中的兰州重离子加速器冷却储存环 ( HIRFL- CSR)的主环加速腔系统用于将累积的重离子束流进行加速 .其频率范围为 0 .2 5 - 1 .7MHz,峰值电压为 8.0 k V.重点介绍了主环加速腔系统的设计及主要高频参数 ,包括高频腔体的设计及低电平控制部分的设计. An ion cooler storage ring HIRFL CSR is constructing at Institute of Modern Physics(IMP). It consists of two rings--main ring (CSRm) and experimental ring (CSRe). For the CSRm, two RF systems will be employed. One is for RF stacking, and another is for beam accelerating. The designed parameters of CSRm accelerating system and the control block diagram of RF system are described. The RF accelerating system has a specification of lower and wider frequency range from 0.25 to 1.7 MHz...     

2 MHz/80 kW离子源射频功率耦合系统的设计

介绍了一种用于大科学工程装置中国散裂中子源(CSNS) 功率升级的RF负氢离子源大功率射频功率耦合系统的研制。主要内容包括射频功率耦合系统的构造, 指标计算分配以及具体实现, 重点阐述了射频功率放大器、隔离变压器、阻抗变压调谐器以及配套的电源、控制和冷却系统的设计, 并对整个系统的结构和热设计提出了工程解决方法。针对离子源功率耦合系统的特点作了细致的分析, 并以此为基础, 研制出了一款输出功率达80kW的射频功率耦合系统产品。     

RF system design and measurement of HIRF-CSRe

An RF system for the CSRe (cooling storage experimental ring) is designed and manufactured domestically. The present paper mainly describes the RF system design in five main sections:ferrite ring, RF cavity, RF generator, low level system and cavity cooling. The cavity is based on a type of coaxial resonator which is shorted at the end with one gap and loaded with domestic ferrite rings. The RF generator is designed in the push-pull mode and the low level control system is based on a DSP+FGPA+DDS+USB interface and has three feedback loops. Finally we give the results of the measurement on our system.     

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基于感应耦合等离子体(ICP)技术设计了一套用于在硅基片上制作形成超浅结的等离子体浸没注入(PIII)系统。该ICP PIII系统工作腔室为圆柱形,采用射频功率源,注入偏压源为一脉冲直流电压源,系统与Langmiur探针相连。探针诊断结果表明,该系统的等离子体离子密度达到1017m-3,离子密度径向均匀性达到3.53%。硼和磷的超低能注入试验的二次离子质谱测试结果表明：掺杂离子注入深度在10nm左右,最浅的注入深度为8.6nm(在注入离子密度为1018cm-3时);注入离子剂量达到了1015cm-2以上;掺杂离子浓度峰值在表面以下;注入陡峭度达到了2.5nm/decade。     

基于MTCA的HLS-Ⅱ直线加速器低电平系统改造

合肥光源(HLS-Ⅱ)在重大维修改造之后,其光源性能有了很大的提升。为了进一步实现连续、平稳地供光,需要对其进行恒流改造。恒流运行要求直线加速器的微波功率源有长期的稳定性与可靠性,旧的模拟低电平控制系统满足不了要求。本文基于微型电信计算平台(MTCA)设计实现了数字低电平控制系统,控制微波功率源的幅度和相位,它由以FPGA为核心的数字板卡、射频板卡、 MTCA机箱以及频率合成系统组成。该数字低电平系统工作在2 856 MHz的S波段,在线运行幅度稳定度达到0.04%,相位稳定度达到0.2°,满足恒流改造对直线加速器数字低电平系统0.25°相位抖动RMS值的相位精度要求。     

中国散裂中子源直线射频低电平远程控制软件研制

中国散裂中子源一期工程的直线加速器,共有8套数字化射频低电平控制单元,射频低电平的本地控制属于EPICS的异构系统,无法直接与EPICS客户端进行通信。通过在射频低电平本地控制上位机程序中嵌入一个C#类型的EPICS服务器程序,实现了使用EPICS客户端对射频低电平系统的远程控制, 从而把射频低电平控制系统接入基于EPICS框架的控制系统中。直线射频低电平远程控制投入在线运行以来,运行稳定可靠。     

Characteristics of a high-power RF oscillator based on a pulsedhollow-cathode discharge

The characteristics of a very simple high-power pulsed RF oscillator are presented. This oscillator is based on the use of a low-pressure pulsed hollow-cathode discharge during the periods when its cathode sheath becomes unstable. A set of four different oscillators has been studied in different operating regimes for various values of load resistance. These oscillators were tested and found to produce pulsed power of over 100 kW with efficiency exceeding 20% at frequencies up to 50 MHz. The tests were performed with pulse duration of 14 μs and repetition rate up to 100 Hz. Equivalent circuits of the oscillator for RF loading and for DC current are described. The requirements for a power supply to drive the device as well as recommendations for the oscillator usage are presented     

Conditioning optics for astigmatic gaussian beams at 140 GHz, 0.5 MW

A quasi optical system was designed to couple the RF power coming from a gyrotron with astigmatic gaussian beam output into a transmission line consisting of an oversized corrugated waveguide. The gyrotron is capable of delivering500 KW at140 GHz for0.5 s. The whole system is described together with low power tests on parts of it.     

BEPC Ⅱ注入器相控系统的设计

以2.856GHz频率上相位控制达到±2°为目标,阐述北京正负电子对撞机重大改造工程注入器相控系统设计思路,提出相应的系统实现结构。在分析相控过程的基础上,分解系统指标,把它作为相控系统详细设计和关键部件测试的依据。最后,针对相位测量这一关键问题,给出了具体的实现方法。     

BEPC Ⅱ注入器相控系统的设计

 以2.856GHz频率上相位控制达到±2°为目标，阐述北京正负电子对撞机重大改造工程注入器相控系统设计思路，提出相应的系统实现结构。在分析相控过程的基础上，分解系统指标，把它作为相控系统详细设计和关键部件测试的依据。最后，针对相位测量这一关键问题，给出了具体的实现方法。     

热阴极微波电子枪模拟计算

用模拟计算方法,研究了热阴极微波电子枪的束流动力学行为,采用笛卡尔坐标,编制了准三维模拟计算程序──HOTGUN.计算中除考虑了射频场外,还充分考虑了空间电荷效应(空间电荷场为轴对称场)、肖特基效应及稳态负载效应等.文中给出了HOTGUN程序与PARMELA部分模拟结果及中科院高能所自由电子激光室微波电子枪热测实验台部分实验结果的比较,最后以用于北京自由电子激光器的多腔热阴极微波电子枪为例,给出了详细的HOTGUN程序模拟计算结果.     

Analysis and Numerical Calculations of the Beam-Wave Interaction for Gyroklystron Amplifiers

A four-cavity gyroklystron was designed and optimized after analysis and calculation of RF system and magnetron injection gun, numerical simulations showed that the TE₀₁₁ mode gyroklystron achieved 280kW peak output power, 38% efficiency, 35dB saturated gain with 250Mhz bandwidth centered at 34GHz for a 68 kV, 11A electron beam. The numerical simulation results were used to build a Ka band high power gyroklystron amplifier. In this paper, analysis and numerical calculation results of the beam-wave interaction are presented. The influences of electron beam, RF system parameters, magnetic field, and input RF signal on output power, efficiency, bandwidth and gain are discussed.     

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。     

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。