Upgrade of the TRIUMF on-line isotope separator, TISOL

The operational TISOL thick target, on-line isotope separator at the TRIUMF, 500 MeV proton cyclotron facility has been upgraded to be a production facility with an active experimental program. A new experimental area is now available and modifications are under design to handle remotely the expected radioactively “hot” targets. Two ion source systems are now available, a heated surface of normal design and a new ECR (electron cyclotron resonance) source resulting in ion beams from a wide range of elements. Details of the new upgraded facility will be presented along with its experimental program and plans for the future. The status of the previously proposed accelerated radioactive beams facility, ISAC, for which TISOL is a prototype front-end system, will also be mentioned.     

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.     

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.     

Conceptual design of an 800 MeV high power proton driver

This paper outlines the conceptual design work of a high power proton cyclotron proposed by the China Institute of Atomic Energy (CIAE) for a spallation neutron source, accelerator driven systems, production of radioactive ion beams, and other applications. For this cyclotron the 100 MeV injection proton beam is currently considered to be provided by the CYCIAE-100 cyclotron, which is under construction at CIAE and will be later replaced by a dedicated injector for beam upgrading. In order to minimize beam losses for high intensity operation, large turn separation at the extraction has first priority. After analyzing of different scenarios, including super conducting designs, a warm magnet solution was chosen. The conceptual design, field calculations, RF cavity simulations, etc. will be presented in the paper.     

Extension of Spallation-Based BNCT Concept to Medium- to High-Energy Accelerators

Following our systematic studies on a cyclotron-based neutron source for Boron Neuron Capture Therapy (BNCT), we expanded our investigation to include medium- to high-energy accelerators with a proton energy range of 30 to 600MeV using a spallation reaction and appropriate moderating materials. The results showed that a spallation-based neutron source for BNCT can be realized without any significant engineering difficulties by applying a commercially available high-current cyclotron and the linear accelerator at the Japan Proton Accelerator Research Complex (J-PARC). A proton therapy accelerator cannot be directly applied for BNCT due to the low beam current. However, the use of a proton therapy accelerator will be especially effective because the proton therapy for localized cancers is complemented with BNCT, which is ideal for treating nonlocalized and radio-resistant cancers.     

用于硼中子俘获治疗的强流质子回旋加速器中心区结构优化设计

中国原子能科学研究院目前正在研制用于硼中子俘获治疗（BNCT）的强流质子回旋加速器,该加速器设计引出能量14 MeV、质子束流强大于1 mA。相比引出流强为400 μA的PET回旋加速器,BNCT强流质子回旋加速器对中心区相位接收度和轴向聚焦的要求更高。为实现mA量级的束流的加速和引出,BNCT强流质子回旋加速器采取了增加负氢束流注入能量、增大磁铁镶条孔径、使用用于增大Dee盒头部张角的阶梯状结构及调整加速间隙的入口和出口高度等一系列中心区结构优化设计,有效地提高了中心区的相位接收度,改善了轴向电聚焦。在新的离子源注入能量下通过数值计算得到实测场下的轴向电聚焦和间隙高度的关系,选取合适的间隙高度获得最佳的轴向聚焦,从而确定了mA量级束流的注入和加速的中心区结构。同时在设计中考虑空间电荷效应的影响,计算了不同流强下的束流尺寸变化。中心区结构在实测磁场下的优化设计计算结果表明,BNCT强流质子回旋加速器中心区的束流对中好于0.5 mm,相位接收度大于40°,中心区最高可接收流强3 mA。目前,新的中心区结构已进入机械加工阶段。     

300MeV/A H_2~+可变能量超导回旋加速器束流引出物理设计研究

针对单粒子效应测试对质子束能量的要求,中国原子能科学研究院设计了一台300 MeV/A H_2~+超导回旋加速器,该加速器使用超导线圈实现主磁铁小型化,剥离引出H_2~+离子获得可变能量的质子束。通过调节剥离点位置和分析剥离后质子的轨迹与束流包络,对该加速器引出过程的束流动力学进行了研究,完成了引出过程的物理设计。结果表明,此台加速器可在205~240 MeV、265~300 MeV内连续变能量引出质子,在更低能量范围内有单能量点引出质子的能力。     

Nonreciprocal properties of 1D magnetized plasma photonic crystals with the Fibonacci sequence

In this paper, the nonreciprocal properties of a novel kind of 1D magnetized plasma photonic crystals(MPPCs) with the Fibonacci sequence are investigated. The isolation of the proposed 1D MPPCs is also used to analyze the nonreciprocal properties. Compared to the conventional 1D MPPCs with periodic structure, the nonreciprocal performance can be significantly improved.The effects of several parameters of the proposed 1D MPPCs on the nonreciprocal properties are studied by the transfer matrix method, which includes the incident angle, order of the Fibonacci sequence, plasma frequency, plasma cyclotron frequency and plasma filling factor. The obtained results show that the nonreciprocal propagation properties can be improved by increasing the values of the plasma cyclotron frequency and incident angle, but they will worsen by blindly increasing the order of the Fibonacci sequence, plasma frequency and filling factor of plasma.The peaks of transmittance also are obviously reduced. In addition, the value of isolation will increase with increasing the incident angle, order of Fibonacci sequence, plasma frequency and plasma filling factor. However, when the plasma cyclotron frequency is increased, the value of isolation will be increased at lower frequencies, but is almost unchanged at higher frequencies.     

电子回旋波Ohkawa机制电流驱动计算

从电子回旋波电流驱动的机制出发,理论推导出了Boozer-Fisch电流与Ohkawa电流的计算表达式,并给出了具体的计算方法。数值模拟结果表明:电子回旋波的波功率沉积在托卡马克高场侧的离轴位置时,Ohkawa电流较小,Boozer-Fisch电流能达到较大值;波功率沉积在低场侧的离轴位置时,通过调整波参数,有效抑制Boozer-Fisch电流,能充分利用Ohkawa电流的优势使离轴驱动电流同样能达到较大值。     

中国原子能科学研究院回旋加速器束流动力学与多物理场模拟技术发展与应用

经过60年的发展,中国原子能科学研究院（CIAE）独立自主地开展了基于PIC技术的强流回旋加速器束流动力学的大规模并行计算的核心算法研究,开发了CYCPIC2D、CYCPIC3D和OPAL-CYCL等强流回旋加速器束流动力学模拟程序,搭建了专用的高性能并行化计算机群PANDA。本文以CIAE已建成及在研的不同类型的回旋加速器为例,总结了回旋加速器基本束流动力学的分析方法和主要计算结果,并介绍了CIAE在回旋加速器束流动力学与多物理场模拟技术方面的发展与应用。     

A 40 keV cyclotron for radioisotope dating

We have built and begun testing a small low energy negative ion cyclotron for direct detection of ¹⁴C. At present, the cyclotron is operated in a high resolution mode at the 31st harmonic, with 1–2 kV on the dees. The high harmonic and a minimum number of turns of approximately 100, should give a fwhm mass resolution of about $\text{1}\text{30000}$ — sufficient to suppress the background from molecular ions such as ¹³CH^?. Background such as scattered ions of ¹²C^? and ¹³C^? should be totally suppressed by the cyclotron acceleration process. (At the 88″ cyclotron at LBL we found that ions only 1% off-resonance are suppressed by more than a factor of 10¹⁷.) A miniature Cs sputter source located at the center of the cyclotron is expected to provide more than 1 μA of negative carbon ions. Negative ions are used in order to eliminate the interference from ¹⁴N. Unlike high energy cyclotrons, focussing is obtained solely from the axial components of the accelerating electric field. The magnetic field is kept flat to within 1 part in 10⁴ in order to maintain exact isochronism throughout the several thousand accelerating rf cycles. The low final energy of 40 keV eliminates any danger from radiation or need for shielding, and the final orbit radius of only 10.5 cm, reduce the size and cost of the machine to that of conventional mass spectrometers.     

Development and application of a new method to shim first harmonic in compact cyclotron

In order to adequately eliminate 1st harmonic in the magnetic field of the compact cyclotron, CIAE has developed a 1st harmonic shimming method that can be applied to the four-sector compact cyclotron. The amplitude of the 1st harmonic can be reduced by adjusting the azimuthal width of the shimming bars at both sides of the sector in this method. Based on the beam dynamics requirement on the amplitude of 1st harmonic, the principle of 1st harmonic shimming method is illustrated through numerical analysis, and meanwhile, the shimming has been implemented on the magnet of CYCIAE-CRM by processing the azimuthal width using NC milling machining. The shimming result shows that it satisfies the requirement of beam dynamics. The shimming effect using this method is also analyzed and expounded in detail. The extension of this method is conducted so that it can be used to shim β_θ at the median plane induced by the installation error of the upper and lower sector poles.     

Overall design of CYCIAE-14, a 14 MeV PET cyclotron

Based on a 10 MeV CRM cyclotron developed at China Institute of Atomic Energy (CIAE) with an achieved beam intensity of up to 430 μA, a 14 MeV high intensity compact cyclotron, CYCIAE-14, was designed and being built at CIAE. It is planned that the first machine would be in place with a span of 2 years. CYCIAE-14 is delicately designed to realize strong vertical focusing by adopting a 4-sector, variable hill-gap structure with an external ion source to achieve high intensity. A special design applied to the stripping extraction gives access to dual extraction with four beams. The adoption of sophisticated industrial technology will give the cyclotron advantages, e.g. low power consumption and high reliability. This paper is aimed to present the overall design of the machine, including the basic technical specifications, main magnet and coils, RF, ion source and axial injection, and stripping extraction, etc. It will also give an introduction to its construction schedule as well as the up-to-date progress.     

Non-Intercepting Ion Phase Measuring Equipment of the Isochronous Cyclotrons at Karlsruhe and Julich

A non-intercepting ion phase measuring equipment is in use at the Karlsruhe cyclotron. Five phase signals, steadily and simultaneously displayed are presenting a good survey of phase width and phase distribution versus radius. High noise immunity is obtained by the use of differential electrostatic pickup probes. Concerning the Jülich cyclotron a similar device with twelve double electrostatic probes is in construction.     

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.     

Method on Adjustment of Isochronous Field Change Caused by Temperature Increase for CYCIAE-100 and Experimental Study on Coil Insulation

In the compact cyclotron with small magnetic pole gap, it places high requirement for the isochronous filed, as is the case with the 100 MeV high intensity cyclotron under construction at CIAE. As the gap between the sectors is small, magnetic field in the gap is sensitive to the magnetic pole deformation caused by factors such as temperature increase and electromagnetic force while the machine is in operation. In this case, the isochronous filed should be maintained by compensating the field divergence caused by pole deformation on line to guarantee the normal accelerating of the particles.     

Cyclotron instability in ogra

Conclusions The experimental results reported here indicate that a cyclotron instability can and does develop in Ogra. Furthermore, at the present time, as far as we know there is no other possible explanation for the anomalous magnitude and the dependence of electric field (at the cyclotron frequency) on plasma density observed experimentally. The presence of density waves with different phase velocities can cause electron heating and electron loss. In this regard, the fact that the electrons can interact with the electric waves seems to be indicated by experiments with an electron beam carried out by Yu. A. Kucheryaev and D. A. Panov [9]; these experiments indicate that an electron beam passing through a plasma along the magnetic field loses or gains energy by virtue of interaction with waves at the cyclotron frequencies corresponding to H ₂ ⁺ and H ₁ ⁺ ions.On the one hand, the effect of the cyclotron instability can cause ions to form bunches as a result of nonlinear effects, and these can lead to a more effective interaction, with the dissipation and exchange of energy. On the other hand, the existence of electric fields perpendicular to the magnetic field can cause ion drift across the magnetic field when the phase velocity of these waves is approximately equal to the ion velocity. As is evident from the table, this situation can arise in certain modes of operation. For a more detailed explanation of the effect of the cyclotron instability on ion loss and electron loss, it will be necessary to carry out further investigations. The author wishes to take this opportunity to thank I. N. Golovin for his continued interest in this work and for a number of valuable comments offered in discussions of the experimental results. E. P. Velikhov for help in carrying out the calculations, and A. N. Karkhov and V. F. Nefedov for help in carrying out the measurements with Ogra. Fruitful discussions of the experiments and the results of the calculations with colleagues working with Ogra were very helpful in determining the physical pattern of these effects.Translated from Atomnaya Énergiya, Vol. 14, No. 1, pp. 72–81, January, 1963     

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.     

Isotope separation in a magnetized sheet plasma by ion cyclotron resonance

The isotope separation experiment in a sheet plasma has been studied by using ion cyclotron resonance heating. The sheet plasma flowed into two parallel plate electrodes to which an rf electric field with a frequency equal to an ion cyclotron for the desired isotopic species was applied. The observed resonance frequency is 180 kHz, however, the ion cyclotron frequency of Ar ion is 65 kHz. This discrepancy may be explained in terms of plasma space potential in the sheet plasma. The ion saturation current in a Langmuir probe gives a maximum value of 6.7 V/cm and 2.3 kG.     

Progress on the heating and current drive systems for ITER

The electron cyclotron (EC), ion cyclotron (IC), heating-neutral beam (H-NB) and, although not in the day 1 baseline, lower hybrid (LH) systems intended for ITER have been reviewed in 2007/2008 in light of progress of physics and technology in the field. Although the overall specifications are unchanged, notable changes have been approved. Firstly, it has been emphasized that the H&CD systems are vital for the ITER programme. Consequently, the full 73 MW should be commissioned and available on a routine basis before the D/T phase. Secondly, significant changes have been approved at system level, most notably: the possibility to operate the heating beams at full power during the hydrogen phase requiring new shine through protection; the possibility to operate IC with 2 antennas with increased robustness (no moving parts); the possible increase to 2 MW of key components of the EC transmission systems in order to provide an easier upgrading of the EC power as may be required by the project; the addition of a building dedicated to the RF power sources and to a testing facility for acceptance of diagnostics and heating port plugs. Thirdly, the need of a plan for developing, in time for the active phase, a CD system such as LH suitable for very long pulse operation of ITER was recognised. The review describes these changes and their rationale.