中国原子能科学研究院回旋加速器创新与发展60年

中国原子能科学研究院（CIAE）自1958年首台回旋加速器成功出束以来,已经历了60余年的回旋加速器创新与发展,并由此带动了我国核科学技术基础研究和应用技术的发展。本文在简要回顾回旋加速器前30年发展历程的基础上,重点阐述后30年围绕紧凑型回旋加速器的科技创新和应用,主要包括100 MeV强流质子回旋加速器、医用小型回旋加速器、质子治疗超导回旋加速器及高功率等时性圆型加速器等多种先进的质子加速器研发。     

Recent development and progress of IBA cyclotrons

Several cyclotron development projects were recently realized by Ion Beam Applications S.A. (IBA). This contribution presents three of them: (i) the intensity enhancement of the Cyclone 30 cyclotron, a machine mainly used for the production of SPECT isotopes. This project is related with the increased demand for ²⁰¹Tl because of the shortage of Mo/Tc generators from nuclear reactors, (ii) development of a new versatile multiple-particle K = 30 isotope-production cyclotron (the Cyclone 30XP) being able to accelerate H⁻, D⁻ and also α-particles. The α-beam of this cyclotron will allow the production of new therapeutic isotopes (e.g. ²¹¹At) and (iii) commissioning of the Cyclone 70 cyclotron installed for Arronax in France. This machine is similar to the C30XP but provides higher energy (K = 70) and allows research on new types of medical isotopes.     

CYCIAE-30医用回旋加速器束流输运系统升级改造

在中国原子能科学研究院CYCIAE－30医用回旋加速器现有的束流输运系统的基础上，根据气体靶生产新品种医用同位素的技术要求，用TRACE－3D对束流输运系统的升级改造方案进行设计，包括束流线的总体布局和光学设计。根据束流光学设计的结果，〖JP3〗设计了新增束流线的磁四极透镜和偏转磁铁。     

A Small "Cold-Cathode" High-Intensity Cyclotron Ion Source

High beam currents have been achieved with a radial source which fits into the 2-inch gap of a 30-inch cyclotron. The geometry is that of a cold-cathode or P. I. G. source. However, the cathodes are heated to thermionic temperatures by ion bombardment rather than a conventional high-current heated filament. The source is now in use and produces intense beams of H+, D+, He3, and alpha particles. Internal beams of H+ or D+ of more than one mA are obtained routinely at extraction radius. In addition, 30 ?A of H- or D- are obtained at a stripping foil by merely reversing the magnetic field of the cyclotron.     

中国原子能科学研究院紧凑型强流质子回旋加速器剥离引出技术研究

中国原子能科学研究院(CIAE)在20世纪90年代建造了一台30 MeV紧凑型强流质子回旋加速器后,经过近30年的发展,先后自主研发成功了基于剥离引出技术的能量为10 MeV、14 MeV、100 MeV、硼中子俘获治疗用14 MeV/1 mA等系列能量的紧凑型强流质子回旋加速器。建成的100 MeV紧凑型强流质子回旋加速器(CYCIAE-100),是目前国际上能量较高的一台紧凑型强流质子回旋加速器,最高流强达到520 μA,束流功率达到52 kW。建成的硼中子俘获治疗用的质子回旋加速器,也是我国首次自主研发成功的引出质子束流强达到mA量级的强流质子回旋加速器。在系列能量的紧凑型强流质子回旋加速器研发过程中,CIAE对剥离引出后的束流色散效应、剥离膜与束流夹角对引出后的束流品质的影响、单圈剥离引出技术等紧凑型强流质子回旋加速器剥离引出技术等方面展开了研究,且自主开发出了剥离引出计算程序,为紧凑型强流质子回旋加速器的应用作出了贡献。     

Results of ICRF Heating Experiments from the EAST 2010 Campaign

Radio frequency(RF) plasma heating in ion cyclotron range of frequencies(ICRF)was successfully performed on the Experimental Advanced Superconducting Tokamak(EAST).This is mainly because lithium wall conditioning was routinely used to reduce both impurity and hydrogen(H) recycling and to improve the ICRF power absorption.Mainly ICRF heating of the H minority regime at 27 MHz has been applied in deuterium plasmas.The ion cyclotron resonance heating(ICRH) is found to depend strongly on plasma preheating.The ICRH efficiency can be much improved in conjunction with the lower hybrid wave(LHW).Effective ion and electron heating was observed with the H minority heating mode.The increase of the stored energy reached30 kJ in L-mode plasma by using the ICRF power of 1.0 MW alone when the H cyclotron resonance layer was at plasma center.     

SUNIST Microwave Power System

Experiments on the start-up and formation of spherical tokamak plasmas by electroncy clotron heating alone without ohmic heating and electrode discharge assisted electron cyclotron wave current start-up will be carried out on the SUNIST (Sino United Spherical Tokamak) device.The 2.45 GHz/100 kW/30 ms microwave power system and 1000 V/50 A power supply for electrode discharge are ready for experiments with non-inductive current drive.     

An automatic phase-matching technique of CYCIAE-100 cyclotron

The RF system of CYCIAE-100 cyclotron has two cavities,which are driven separately by two identical 100-kW RF amplifiers.Due to the power on sequence issue of the three DDSs in the LLRF systems,each time when the system is individually switched on,the phase relationship may not satisfy the requirements of beam acceleration.Instead of adding an extra reset logic to the system,a search and validation algorithm based on the decision tree has been carried out to make sure the phase of the two cavities is correct right after applying power to the cavities,taking advantage of existing hardware resources.In the first year of operation,there are more than 20 times of scheduled shutdown of the cyclotron system.For each time when the cyclotron RF system is completely shutdown and powered on again,the operator confirmed that the phase matching of the two cavities can be done automatically within 30 s.The related work,including the optimization of the phase detector and the development and validation of the algorithm,is reported in this paper.     

ITER中的电子回旋波电流驱动模拟

通过将相对论Fokker-Planck方程与波迹方程联合求解,对ITER(国际热核实验反应堆)参数下的电子回旋波电流驱动进行了数值模拟。结果表明,当波的环向发射角度不太大时,波功率沉积将发生在ITER的强场侧。当环向发射角度为21°时,电子回旋波的能量在等离子体中心区域被吸收并驱动起等离子体中心区域的电流。当发射角度变大时,电子回旋波将在弱场侧沉积功率。当发射角度为20°～30°时,能够驱动归一化的径向位置(r/a)小于0.35区域内的等离子体电流,并有较高的电流驱动效率。     

Preliminary Calculations of the Thermal Stress Influence on the Magnetic Field of CYCIAE-100 Project

During the long time operation of the compact cyclotron, the RF power will be fed into the RF cavity Some of the power is used for accelerating the H- beam, while the other is lost by heating the cavity and the magnet pole. Although the cooling water flowing around the outside of the cavity can take away the heat, the temperature of the pole will increase slowly. This phenomenon has been already observed in 1994, when the 30 MeV cyclotron was in operation with temperature variation of the pole about 25 ~C The thermal stress caused by the slow shift of the temperature will dilate the pole and diminish the gap height between the upper and the lower pole, which will result in the change of the magnetic field. Therefore, it is important to investigate the influence of temperature on the field.     

Status report of the Leuven isotope separator on-line (LISOL)

The mass separator LISOL, on-line to the CYCLONE cyclotron, is described as it is presently configured. The main development has been in the ion-guide operation in conjunction with light-ion induced fusion and fission. The plans to obtain intense (nA) beams of light (A ≤ 30), short-lived nuclei in the framework of the ARENAS³ project are also described.     

Acceleration of He3 up to 35 Mev in the one and one-half meter cyclotron

A method is described for accelerating He ₃ ²⁺ to 35 Mev in a cyclotron. A beam of 30 a with an energy spread of ± 0.3% was obtained on a target 12 m from the cyclotron. Due to the use of a gas recycling system, the loss of He₃ was decreased by two orders and was approximately 5 cm³/hr.The authors wish to express their deep appreciation to N. A. Vlasov and S. P. Kalinin for the continuing interest in the project; to V. I. Lamunin and N. N. Khaldin for constructing the gas recycling system; to N. V. Kartashov for tuning the pulsed ion source; to the staffs of the operating group and machine shop who assisted in the preparation of the apparatus and cyclotron inlet system.     

10MeV强流回旋加速器的束流调试

10MeV强流回旋加速器在中国原子能科学研究院研制成功,并取得了先进的束流指标。它是国内自主研发的首台紧凑型强流回旋加速器,具有多项技术特点。在其建造、调试过程中解决了诸多技术问题,作为一个回旋加速器综合实验装置,它不但为在建的100MeV回旋加速器提供了设计验证手段,而且也是强流回旋加速器关键部件的综合实验平台。它的建造成功,为小型回旋加速器的国产化提供了技术保证,为推广加速器在我国核医学领域的应用创造了条件。本文将重点介绍它的调试过程、解决的关键问题及调试结果。     

The residual zonal flow in tokamak plasmas with a poloidal electric field

In a tokamak plasma with auxiliary heating by cyclotron waves, a poloidal electric field will be produced, and as a consequence influence the residual zonal flow(RZF) level. The poloidal electric field can also be induced through biasing electrodes at the edge region of tokamaks.Numerical evaluation for a large aspect ratio circular cross section tokamak for the electron cyclotron wave heating indicates that the RZF level decreases significantly when the poloidal electric field increases. Qualitatively, the ion cyclotron wave heating is able to increase the RZF level. It is difficult to apply the calculation to the real cyclotron wave heating experiments since we need to know factors such as the plasma profiles, the exact power deposition and the cross section geometry, etc. It is possible to use the cyclotron wave heating to control the zonal flow and then to control the turbulence level in tokamak experiments.     

回旋加速器中的空间电荷效应和束晕(英文)

在考虑束团内粒子之间的空间电荷相互作用力的条件下,对日本理化研究所(RIKEN)现有的一台注入器(加速常数为K70的AVF型回旋加速器)中束团的演变过程进行了模拟计算。模拟结果表明,束团的形变、束晕现象同样发生在回旋加速器中,不过,其产生机制不同于直线加速器。它不是由共振和混沌引起,而是由于粒子的排斥运动和束团内粒子的涡流运动引起的。     

100MeV回旋加速器中心区结构设计

中国原子能科学研究院建成了100 MeV紧凑型强流质子回旋加速器,其引出能量为75~100 MeV,流强为200μA。安装在回旋加速器狭小磁极气隙的中心区与螺旋静电偏转板是关键部件,其结构设计涉及磁场、高频电场、高压静电场、真空、传热等方面。本文介绍了中心区与螺旋静电偏转板的结构设计及使用情况。在设计过程中,采取加大绝缘距离、优化高频连接结构、增加杂散束流阻拦装置等措施,解决了中心区与螺旋静电偏转板在强流注入时可靠工作的问题。本文对螺旋偏转板进行了传热分析,得出了该螺旋偏转板在强流束注入时的温度分布。设计的中心区和螺旋偏转板已安装在加速器上,20μA/100 MeV的引出束流通过了12h稳定性测试,在加速器测试过程中,中心区工作稳定可靠。     

On the heating mechanism of electron cyclotron resonance thruster immerged in a non-uniform magnetic field

To study the heating mechanism of electron cyclotron resonance thruster(ECRT) immersed in a non-uniform magnetic field, experiments and simulations are performed based on an electron cyclotron resonance plasma source at ASIPP. It is found that the first harmonic of electron cyclotron resonance is essential for plasma ignition at high magnetic field(0.0875 T), while the plasma can sustain without the first and second harmonics of electron cyclotron resonance at low magnetic field(till 0.0170 T). Evidence of radial hollow density profile indicates that upper hybrid resonance, which has strong edge heating effect, is the heating mechanism of low-field ECRT. The heating mode transition from electron cyclotron resonance to upper hybrid resonance is also revealed. Interestingly, the evolutions of electron temperature and electron density with input power experience a ‘delayed' jump, which may be correlated with the different power levels required for cyclotron and ionization. Moreover, when the field strength decreased, the variation of electron density behaves in an opposite trend with that of electron temperature,implying a possible competition of power deposition between them. The present work is of great interest for understanding the plasma discharge in ECRT especially immersed in a non-uniform magnetic field, and designing efficient ECRT using low magnetic field for economic space applications.     

电镀法制备富集112Cd靶

针对CS-30加速器制备高放射性核纯度¹¹¹In（≥99.9%）所用富集¹¹²Cd靶的电镀工艺进行了探索,首次根据加速器束流轰击径迹（束斑）实现定向区域电镀,在此基础上,对影响富集¹¹²Cd靶质量及厚度的各种因素进行研究,确定最佳工艺条件,最终所得富集¹¹²Cd靶表面光亮、致密、牢固,厚度大于65 mg/cm²。同时初步探索了富集¹¹²Cd靶厚与产额的关系,当富集¹¹²Cd靶厚为90 mg/cm²时,¹¹¹In产额为222 MBq/μA·h。     

Simulation of the Accelerating Systems of Cyclotrons for Applications

The results of a comparative numerical investigation of three types of resonator systems of a cyclotron for acceleration of negative hydrogen and deuterium ions up to maximum energy 30 and 15 MeV, respectively, are presented. It is shown that a vertical system with two half-wave resonators excited in-phase has the smallest active losses and the smallest differential of the amplitude of the accelerating voltage along the edge of the dees and is effective for accelerating particles at dual working frequencies.