质子加速器注入、引出磁铁电源的纹波抑制

在国产首台质子治疗示范装置研制项目中,质子加速器的注入、引出磁铁电源采用模块电源并联方式,但注入、引出磁铁的电感量较小不利于开关电源噪声抑制。为满足项目需要,提出了一种错相设计方案,并推导了三相错相的纹波归一化量值,理论上验证了方案的可行性。在此基础上,用MOSFET以H桥结构作为基本单元,采用3单元移相120°的方式构成模块电源。经测试,3台静磁切割磁铁电源开关纹波满足设计和使用要求,同时证实了电源拓扑结构的可行性。3台电源自投入使用以来,无故障可靠稳定运行20个月以上。     

重离子加速器磁铁电源控制系统研制

重离子加速器通过一定周期的磁场对带电粒子进行约束,磁铁电源是产生所需磁场的关键部件,因此,要求磁铁电源控制系统具备高效性、稳定性、精确性。磁铁电源需按加速器运行周期进行响应运行。重离子加速器磁铁电源的时序必须严格按重离子加速器控制系统的控制时序进行控制。本工作研制了重离子加速器磁铁电源控制系统,通过磁铁电源控制器与同步时钟系统的通信进行控制时序的运行;通过与中央数据库的数据通信获取磁铁电源控制器所需的全部数据(如同步事例数据、波形数据等)。同步时钟信号一旦触发,磁铁电源控制器进行相应的数据获取并进行插值运算输出至磁铁电源进行控制。重离子加速器磁铁电源控制系统同步精度为1μs,实验平台测试控制器平台纹波精度为100ppm,能满足重离子加速器实验运行的要求。     

质子治疗装置脉冲电源研制

上海质子治疗装置项目中质子注入系统凸轨磁铁需要脉冲电源励磁,要求两台电源脉冲峰值幅度可调和波形一致,且运行可靠。本文介绍了凸轨磁铁脉冲电源的设计和测试。脉冲电源电路采用LC串联谐振作为脉冲成形发生电路,电路设计可调电感用于调整波形脉宽。晶闸管为电流开关,快恢复二极管串联晶闸管弥补大功率晶闸管的关断延迟和下冲,并增加饱和电抗器抑制励磁电流反向电流尖峰。测试结果表明,当励磁电流峰值为3 732 A时,励磁电流触发抖动小于±25 ns,励磁电流峰值重复稳定度小于0.1%,反向电流尖峰下降为峰值电流的3.75%,快恢复二极管和饱和电感器对抑制励磁电流反冲的效果明显,满足了设计要求。     

Maintenance Method for Tokamak Fusion Reactors with Downward Access to Torus Inboard Structures

A concept of tokamak fusion reactor maintenance is presented. Reactor structures and maintenance machines are arranged so that the component inside a shielding structure can be replaced through the hatches located on the upper side of the torus shielding structure. The plasma vacuum boundary is constituted by the inside wall of the shielding structure. The magnet vacuum chamber contains two toroidal magnets in a single room, so that strong support structures can be placed between these toroidal magnets. A merit of this reactor is that the inboard reactor structures are accessible with keeping the magnet cryogenic condition and without disassembling any major reactor components. The practicability of this method will depend on the time required to move the blanket segments in the toroidal direction and to weld pipes by remote handling. A number of ideas for reducing this time are presented.     

Simulation and test results of low-order band harmonic filters to decrease resonance phenomenon in the KSTAR power system

The superconducting magnet power supply which supplies superconducting magnet coil (SC) with the power to generate plasma during a KSTAR experiment for nuclear fusion research is a nonlinear load. Characteristic harmonics are generally produced since it converts AC to DC using 6 or 12 pulsed operation. However, non-characteristic harmonics or inter-harmonics are generated according to output control characteristics. Also, 95% out of the power generated from superconducting magnet coil is reactive power. Therefore, harmonic and reactive power occurring during operation have some bad influences such as voltage drop, voltage distortion and decrease in power factor on the KSTAR power system, and reactive power compensator (RPC) & harmonic filter (HF) system which is able to compensate harmonic and reactive power at the same time was established and has been operated [1]. However, out of non-characteristic harmonics and inter-harmonics caused by output control characteristics of superconducting magnet power supply, the more compensation volume of the RPC & HF system increases, the more voltage distortion with harmonic expansion is caused by harmonics in a low-order band due to the parallel resonance in a low-order band between the KSTAR power system and the RPC & HF system. As a result, it has serious effect on the injection capacity restriction of the RPC & HF system, the unstable operation control of superconducting magnet coil, and the operation of main cooling facilities. This paper presents reasons of the resonance phenomenon of the KSTAR power system and suggests a design plan of additional facilities for stable operation of the KSTAR power system, and proves their effects through the simulation and test results.     

中国散裂中子源快周期同步加速器磁铁电源系统的研究

目前正在进行可行性研究的中国散裂中子源的主体结构是1台强流质子同步加速器。该加速器的一期目标为注入能量70MeV、引出能量1.6GeV、束流功率100kW、循环工作频率25Hz。文章阐述系统总体结构的设计原则以及二极磁铁（B）和四极磁铁（Q）磁场的跟踪误差要求。     

Design study of a rotating gantry for the HIMAC new treatment facility

A project to construct a new treatment facility as an extension of the existing HIMAC facility has been initiated for the further development of carbon-ion therapy. In the new facility, one of the treatment rooms will be equipped with an iso-centric gantry system employing a 3D pencil beam scanning irradiation method. In order to realize a compact design, the final 90° bending magnet is divided into two bending magnets of 60° and 30°. The scanning magnets are set between these two bending magnets, although the aperture of the 30° magnet increases. Finally, we achieved 350 tons of total weight for 400 MeV/u carbon beams with a 150 mm square field.     

陶瓷真空室研制及其阻抗的研究

介绍了电子储存环注入凸轨击磁铁及春真空室常采用的几种技术方案。合肥电子储存环新凸轨注入系统选择了铁氧体磁铁内置陶瓷真空室的方式。为了同时满足脉冲磁场穿透性能及束流耦合阻抗的要求,陶瓷真空室的内壁须镀１层金属薄膜。     

Control strategy optimization for energy efficiency and harmonic mitigation in multi-series converters

To provide electrical power for the Research System of Superconducting Magnets (RSSMs) including the background field superconducting magnet and the tested superconducting objects, the high power phase-controlled converter will be used to develop the power supply system. However, because of its inner nonlinear feature, the current harmonics and the reactive power are injected into the AC power supply system. To improve the quality of the power supply system for RSSMs, an improved synchronous control strategy is suggested for the superconducting magnet power supply system, which comprises four series-connected six-pulse converters fed by a phase-shifting transformer, respectively. According to the proposed control strategy, the basic unit is two 12-pulse converters and the control method will be changed in terms of load fluctuations which are represented by the per unit value of converter output voltage. As a result, harmonic is greatly reduced but the power factor is also high.     

Cost-Effective Superconducting Magnet Design for Next-Step Fusion Experiments

It is widely believed that the use of superconducting magnets in next-step fusion experiments is driven only by the reactor relevance of low circulating power in a fusion plant. However, there is a broad range of fusion magnet applications in which the use of superconducting magnets in near-term experiments will reduce the capital cost of an experiment, along with further reductions in the operating cost. This claim extends to Proof-of-Principle and Proof-of-Performance experiments for Steady-State and Spherical Tori, Compact Stellarators, Spheromaks, and Heavy Ion Fusion Drivers.     

旋转线圈测量法测量BEPCⅡ对撞区超导磁铁磁场

北京正负电子对撞机二期工程(BEPCⅡ)中的超导磁铁用来提高BEPCⅡ的对撞亮度,并对闭轨和耦合进行校正。超导磁铁要尽可能靠近对撞点(IP),并浸泡在1.0T的探测器BESⅢ螺线管磁场中。对撞点两侧各有1块超导磁铁,每块都包含有聚焦磁铁SCQ、水平偏转磁铁SCB/HDC、垂直校正子VDC、斜四极子SKQ及反螺线管AS等功能磁铁。利用旋转线圈的测量方法对SCQ、SCB/HDC、VDC、SKQ等进行测量,了解其积分场、高次谐波及沿束流运行方向的局部磁场。通过与BNL在垂直杜瓦中的测量结果进行的比较可知,高次谐波测量结果差别不大;与张力线的比较可知,SCQ及SCB的主极矩偏差小于3×10-3。表明提出的计算方法可进行磁场的绝对测量。     

Structural design features for commercial fusion power reactor magnet systems

The evolution of structural design features for commercial fusion power reactor magnet systems is discussed. Changing concepts in plasma physics and impurity control, new data on radiation damage in materials and developments in the maintainability and repairability of the magnet systems are the driving influences in this evolution.Generic problems in the magnet designs are discussed for several proposed magnetic confinement system configurations, including tokamaks, tandem mirrors, the Elmo Bumpy Torus, and the reversed field theta pinch. These systems are compared on the basis of how efficiently the magnets make use of structural materials.A measure of the effectiveness of a magnet system is found by determining the ratio of net electric power output from the reactor to the stored energy in the magnetic fields produced by the magnet coils in a given system. The stored energy in the magnetic field can then be used to establish a minimum structural volume and mass by use of the virial theorem. Experience with coil types such as solenoids, toroids, Yin-Yang, etc. has established factors by which the minima must be multiplied to yield anticipated volumes and masses of realistic magnet systems. These initial, admittedly approximate, calculations allow designers to estimate early in the process the contribution of the magnet systems to the overall cost of a fusion reactor. As work progresses these estimates can be used to indicate the degree to which the designer is making effective use of the structural material.Basic rules for effective placement of structure, common to all magnet systems, are also discussed in detail. Factors are presented which make it possible to compare structural savings to the cost of researching the parameters involved in the stability of superconductors.     

A Synchronization Pulse for the Princeton-Pennsylvania Accelerator

The basic synchronizing pulse in the P.P.A., tying the injection pulse and the R. F. to the magnetic field, is derived from the total current flowing through one of the Accelerator magnets. This pulse is generated in a biased toroidal coil wound on a supermalloy core, by the magnetic field H(t) created by the magnet current in a coaxial conductor. This method has provided us with a synchronization signal pulse with excellent long term stability and very little time-jitter. Part of the time-jitter may be attributed to the variations of dH/dt at the time of the reversal of the magnetization of the core due to variations of Imin in the magnets. A method has been developed to effectively cancel out the dH/dt effect in the supermalloy core.     

Potential influence of reliability analysis on component design in fusion reactors

Questions of reliability and availability play an increasing role in fusion technology. Considering the large amount of technical efforts and capital spent, the risk of undesirable developments arising from inappropriate design must be kept as low as possible. The existing data base is extremely small to yield fully conclusive results already now. But in many cases acceptable solutions of technical problems with regard to reliability are achievable, if design precautions compensate for the uncertainty in data. This principle will be demonstrated in two examples: a neutral beam injection power supply control system and a power supply control system for superconducting magnets. The method used for reliability analysis is based on the Boolean algebra with restricted variables [1], which allows to identify weak and critical points in the design especially by representing results in block diagrams. The method has the additional advantage that not only the influence of the reliability of single components but also of complete subsystems on the overall result can be evaluated easily. By varying the input data or altering the design supplementing parametric studies can be performed. This is very important for investigating design alternatives, and, therefore, already now the method is a support in systems reliability analyses of fusion plants components and subsystems.     

BEPCⅡ磁铁电源快速检测系统的实现

为使北京正负电子对撞机（BEPCⅡ）在运行时能快速找到磁铁电源引起的加速器束流不稳定或丢束的原因,研制了磁铁电源快速检测系统。该检测系统主要采用PXI系统,其8 h稳定度达0.005%,最快可在0.33 ms内采集一遍近500套磁铁电源电流值,所有历史数据均通过TCP/IP传输并实时写入远程MySQL数据库,从而可通过数据库的数据分析比对迅速排查电源电流稳定度问题。     

HIRFL-CSR二极磁铁电源的研制

研制了兰州重离子加速器冷却储存环(HIRFL-CSR)二极磁铁电源,提出了一种基于晶闸管相控整流技术和IGBT脉宽调制(PWM)变换技术的同步加速器二极磁铁电源的设计方案,分析、仿真了其工作原理,并设计、生产了1套完整的电源样机。经现场试验、长期运行及测试,电流稳定度±5×10-5/8h,跟踪精度±2×10-4,电流纹波1×10-5。该方案满足HIRFL-CSR二极磁铁对电源技术指标的要求。     

60A／200V重离子扫描磁铁供电三角波电源

给出了５０Ｈｚ６０Ａ／２００Ｖ重离子扫描磁铁供电三角波电源的设计原理、技术指标、方案选择和研制结果。     

高能大功率电子辐照加速器270°偏转光路设计

为实现高能大功率电子辐照加速器的一机多用目的,需研制270°偏转光路支线。本文采用Trace3D程序对270°偏转光路进行了设计与模拟计算,设计了双135°偏转磁铁和整体270°偏转磁铁。对双135°和整体270°两种偏转磁铁元件进行二维和三维电磁场设计与模拟计算,计算结果表明,整体270°偏转磁铁的场分布与光路设计中所要求的物理参数差距较大。由于整体270°偏转磁铁的场分布调整较困难,使工程实施中的束流调试难度较大,因此采用双135°偏转磁铁的光路方案。     

The operational results of the KSTAR PF cryo-circuit

The Koreas Superconducting Tokamak Advanced Research (KSTAR) PF cryo-circuit is designed for cooling the fourteen superconducting magnets (Nb3Sn, NbTi) and structures. Those are cooled down by the supercritical helium (4.5 K and 5.5 bar) of a forced flow (pressure gradient: 2 bar) in order to maintain the supercritical state of the helium. To supply a large amount of supercritical helium (>370 g/s), a circulator was inserted into the PF cryo-circuit. The compressed supercritical helium is distributed to five helium manifolds with cryogenic valves and supplied to each PF magnet. While the PF magnets had been operating, the mass flow rate reduced and the pressure head of the circulator was fluctuated depending on the PF magnet operation scenario. These phenomena could damage the circulator and could stop it during operation. Therefore, by-pass valve, which is parallel with in-line valve and is connected with inlet and outlet of the magnet, was opened in order to reduce of the circulator's pressure head. In this paper, we focused on the helium behavior of the superconducting magnet when the by-pass valve was opened in order to release the pressure head of the circulator and the results will be presented.     

北京正负电子对撞机重大改造工程中超导磁体电流引线设计

北京正负电子对撞机重大改造工程（BEPCⅡ）中超导聚焦四极磁体(SCQ)共有6对电流引线，输送4种不同大小的电流。超导探测器磁体(SSM)由1对4000A的电流引线输送电流。本文为SCQ和SSM两个超导磁体设计多层套管结构的电流引线。引线通过在低温端增加大质量铜座的方法来延长当冷却氦气消失时低温端温度上升到超导导线失超温度的时间。给出了多层套管结构电流引线稳态与非稳态大型CFD软件Fluent6.0数值模拟结果。