A Source for Multiply-Charged Ions and Acceleration of C, N and O Ions by IPCR Cyclotron

The design and performance of the ion source which is now used in the IPCR variable energy cyclotron are described. The source is of the electron-bombarded hot cathode type having two cylindrical cathodes of tungsten and a water-cooled copper anode containing a replaceable molybdenum slit plate. The arc discharge is established continuously but not pulsed. The source is usually operated very stably under an arc power of 1.5 to 3kW with a gas flow rate of 1 to 2 cc/min. The lifetime of the source is mainly limited by the erosion of the upper tungsten cathode at about 24 hours. At present, C4+, N4+, O4+, N5+ and O5+ ions are accelerated up to 48~100, 56~1100, 70~95, 56~125 and 70~125 MeV respectively, and a few micro-amperes of these ions are extracted from the cyclotron. The vacuum obtainable in the accelerating chamber is usually 2 ~ 4 × 10-6 mHg, and the loss of ion beam by the charge exchange effect is comparatively small. Extracted ion beams are used in several experiments for about 1900 hours in a year.     

Production of Multiply-Charged Ions of Ne, Ar, Kr and Xe by the Electron-Bonbarded Hot Cathode IoN Source of IPCR

Production of multiply-charged ions of Ne, Ar, Kr and Xe has been studied by use of an electron-bombarded hot cathode type ion source of the IPCR 160cm cyclotron, which is similar to Morozov's source. These multiply-charged ions were accelerated by a 3rd harmonics acceleration mode in the cyclotron and detected with a beam probe fixed at the radius of 55cm. Observed multiply-charged ions are Ne2+, Ne3+, Ne4+, Ne5+, Ar3+, Ar4+ Ar5+, Ar6+, Ar7+, Ar8+, Kr6+, Kr7+, Kr8+, Kr9+, Xe9+, Xe10+ and Xe11+. Relative abundance of each charge state of four elements were measured. In case of Kr and Xe , the intensity of observed multiply-charged ions decreased to 1/3 or 1/4 when the charge number is increased by one. Intensities of Ar4+, Ar6+, Ar8+, Kr6+ and Kr8+ were measured as a function of the operation conditions of the ion source, such as arc voltage, arc power and gas flow rate. It was found that a smaller gas flow and a higher arc power brought about a higher yield in all the measured ions. Obtained current intensities of ion source output are 40?A Ar8+, 600?A Kr6+, 40?A Kr9+, 150?A Xe9+ and 10?A Xe11+ respectively.     

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.     

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。     

BRISOL钾同位素放射性核束的产生

北京放射性核束装置在线同位素分离器（BRISOL）采用一台100 MeV回旋加速器提供的最大200 μA的质子束打靶在线产生放射性核束,其最高质量分辨率好于20 000。2015年,BRISOL装置建成并使用05 μA质子束轰击氧化钙靶产生了37K+、38K+放射性核束,其中38K+的产额为1×106 pps。为了提高氧化钙靶产生钾放射性核束的产额以满足物理用户需求,BRISOL于近期开展了氧化钙靶的在线实验。实验中使用氧化钙靶产生了36～38K+、43K+、45～47K+等多种放射性核束,同时将38K+的最大产额提高到了112×1010 pps。本文详细介绍氧化钙靶的研制及在线实验结果。     

The ORNL ECR multicharged ion source

A multicharged ion source based on electron cyclotron resonance (ECR) heating has been designed and built at ORNL. The ECR ion source, which is completely dedicated for atomic physics collisions studies, produces higher charge states and higher beam intensities than the present ORNL PIG multicharged ion source, and will thus permit study of collision processes involving ions of higher charge states in experiments requiring higher beam intensities than could be previously obtained in our laboratory. The source has already produced up to fully stripped C and O beams, as well as up to He-like Ar beams. Measurements of the energy spread of ions extracted from the ion source operating in both single-stage and two-stage mode are described. In addition, initial results of total cross section measurements for fully stripped light ions incident on atomic hydrogen in the energy range 0.2–10 keV are presented.     

北京放射性核束装置在线同位素分离器的研制

北京放射性核束装置在线同位素分离器（BRISOL）采用100 MeV、200 μA回旋加速器提供的质子束打靶产生中、短寿命放射性核束,进行在线分析后供物理用户使用,其质量分辨率好于20 000。BRISOL装置现已建成,并开展了氧化镁、氧化钙靶的在线实验,在线产生了³⁷K⁺、³⁸K⁺、²⁰Na⁺、²¹Na⁺等多种放射性核束。本文详细介绍该装置的研制及运行情况。     

Production, acceleration and use of radioactive ion beams at Louvain-la-Neuve

The production and acceleration of radioactive beams using two cyclotrons coupled by an electron cyclotron resonance ion source is described. Pure beams of ¹³N(T1/2 = 9.96 min) and ¹⁹Ne(T1/2 = 17 s) with an energy around 1 MeV/amu are obtained with intensities larger than 50 ppA. As an example, cross section measurements using a ¹³N beam on hydrogen and deuteron targets are presented. Finally, the ARENAS³ project, a future plan for the production of radioactive beams in Belgium, is described.     

Electron Capture and Loss Processes in Heavy Ion and Molecular Ion Collisions with Solids

Angular (?) and velocity (ve) distributions of convoy electrons have been measured with monoatomic and molecular projectile ions (H+, D+, H+2, D+2, H+2, He+, He++ at 1.7 MeV/U and U+44, Ti+14 at 1.4 MeV/U) as a function of the projectile dwell time tD in carbon foils (2 to 50 ?g/cm2). The spectra with light projectiles from carbon foils are compared with those of gaseous CH4 targets. For the light and molecular projectiles the shapes and yield of convoy electrons depend strongly on the dwell time. A narrow, strongly ?-dependent contribution at Ve = vp can be distinguished from a ?-independent part at Ve < vp indicating different production mechanisms. A relation is presented which connects the yield of loss electrons from projectiles with the transmission of projectiles and electrons through solids. The yield of electrons in the spectrum for H+2 at ve = vp and under zero degrees is found to be more than about 20 times as large as is expected from the contribution of loss electrons in last layer collisions.     

用GC-GCMS分析氢、氦同位素及氧、氮、一氧化碳的含量

本文叙述了用氖气作载气的毛细管热导池气相色谱(GC)与气相色谱-质谱(GCMS)并联的方法,同时准确地测定氢、氦同位素及氧、氮、一氧化碳的含量。样品量为10μl,测量精度为1.5-2.0％。用GCMS法测量了HD,HT和DT的原子离子与母体分子离子的比值,并发现同一母体离子的两种组成同位素的原子离子与分子离子的比值是不相等的,还观察到了CO对低温色谱柱分离性能的影响。     

Modification of an Ion Source for the Production of Microampere 4He- Beams

Several modifications of the ion source of a model EN Tandem Van de Graaff Accelerator have increased the production of 4He- beams by a factor of 100 over that first obtained with the source (~10 nA). While using H2 gas for charge exchange, the replacement of the source drift tube by a screen and the installation of a system for precise adjustment of the button alignment with respect to the extractor electrode increased the output to 150 nA at the ion source. Recently potassium vapor has been used for charge exchange. Since the introduction of this technique, 4He- beam currents of 1. 2 ?A have been regularly produced. The 4He+ ions from a duoplasmatron ion source are accelerated to 20 keV and passed through the standard exchange canal which is modified by the addition of a potassium vapor chamber. Analyzed 4He++ beams of 0.3 to 0.8 ?A have been obtained with terminal voltage between 1.8 and 6 MV. The modified source has been used with K-vapor exchange for continuous periods of up to 120 hours without deterioration of source performance. Normal operation with H2 gas exchange for other beams is possible without the interruption of the source operation.     

Electron Cyclotron Resonance Multiply Charged Ion Sources

We describe three ion sources working in our laboratory that deliver multiply charged ion beams. All of them are E.C.R. ion sources and are characterized by the fact that the electrons are emitted by the plasma itself and are accelerated to the adequate energy through electron cyclotron resonance (E.C.R.). They can work without interruption during several months in a quasi-continuous regime. (Duty cycle: <.5). Their charge state distributions (C.S.D.) depend on the size and the characteristics of the plasma. For the smallest source the performances are comparable to those of P.I.G. sources. For the biggest source, the C.S.D. tend towards those obtained by EBIS-type sources. Experimental results and guiding ideas concerning these three ion sources are reviewed.     

离子源及厚靶参数对氘氚反应中子源中子产额的影响

用厚靶氘氚(D-T)反应中子产额的计算方法模拟计算了入射氘离子能量为120 keV时D-T中子源的中子产额。研究了氘离子源产生的束流中单原子氘离子(D+)及双原子氘离子(D2+)比例对中子产额的影响。结果表明,提高D+比例,同时降低D2+比例将有效提高中子产额。另外还研究了不同靶膜材料及组分引起的中子产额变化。表明中子产额与靶膜中氚的含量成正比,与靶膜元素的原子质量成反比。同时分析讨论了离子源品质及靶参数对中子源整体性能的影响,得出离子源束流品质的提高对中子源整体的设计至关重要。最后,模拟计算了靶膜表面有氧化层情况下中子产额的变化,并与实验结果作了对比。在此基础上提出了一种新的靶设计方案,并对其物理可行性进行了研究。     

Mixed Ne/Ni beams for radiation damage studies on the harwell variable-energy cyclotron

Ion irradiation facilities which use metal ions beams concurrently with beams of He or He+H have been developed extensively in recent years for the simulation of radiation effects which occur in metals during neutron irradiation in fission or fusion reactors. Helium ions are considered necessary to simulate the effect of helium on cavity nucleation and the metal atom is used to create an adequate atomic displacement rate. Many of these dual-beam facilities require the provision of two accelerators, one to produce a gas atom and the other a metal atom beam, and commonly employ low-energy metal ions (eg. 4 MeV ⁵⁸Ni⁺) which have a limited range (0.75 μm) in metals of practical interest. Damage can be created at greater depths by use of high energy ions (eg 45 MeV ⁵⁸Ni) in a cyclotron, but charge-to-mass constraints make it difficult to produce a mixed beam of concurrent He and metal ions. It is noted that the heavier inert gas atom neon has similarities in atomistic behaviour in metals to those of helium and could possibly be used as an analogue for helium. In this report we consider this aspect and show than by suitable matching of $\text{e}\text{m}$ ratio a mixed beam of 15 MeV ²⁰Ne²⁺ and 45 MeV ⁶⁰Ni⁶⁺ can be obtained from the Harwell VEC with gas/metal atom ratios and beam currents that are suitable for use in radiation damage simulation experiments in metals. It is proposed that exploratory studies should be carried out with mixed Ne/Ni beams into nickel to investigate the possibility of using neon as an analogue for helium in radiation damage simulation studies.     

Performance of ANL 4-MV Dynamitron with Heavy-Ion Source

The performance of the ANL 4-MV Dynamitron accelerator using a Danfysik heavy-ion source is briefly described. Using CC14 support gas, 2 ?A beams of 58Ni+ were obtained at 3.5 MeV and 6 ?A beams at 2 MeV by optimizing source chemistry.     

Heavy Ion Source with Pulsed Magnetic Field

A compact P.I.G. ion source with pulsed field and end extraction is described. The source produces multiply ionized N, C, Ne, A, Kr and Xe. Pulsed currents of C3+, N3+, Ne3+, A3+, Kr3+ , Xe6+ between a few tens of ?A and a few hundreds of ?A have been obtained. Small size and power consumption make it compatible with a Van de Graaff terminal where space and power are at a premium.     

BRISOL钠同位素放射性核束的产生

北京放射性核束装置在线同位素分离器（BRISOL）采用100 MeV、200 μA回旋加速器提供的质子束打靶产生中、短寿命放射性核束,在线分析后供物理用户使用,其质量分辨率好于20 000。为开展²⁰Na核的奇异衰变特性研究,研制了氧化镁靶,并采用100 MeV质子束轰击氧化镁靶在线产生了^20～26Na⁺的钠同位素放射性核束。当质子束流强为8 μA时,²⁰Na⁺离子束的最大产额为2×10⁵ s^-1,²¹Na⁺离子束的最大产额为4×10⁸ s^-1。完成了北京放射性核束装置首个放射性核束物理实验,累计供束近200 h。     

电解法制备高纯度18O2

采用自行设计制造的石英玻璃电解装置,以重氧重水为原料,通过碱性介质电解法进行了18O气体的制备,在原料重氧重水18O的摩尔分数>80%条件下,最终制得18O气体中18O2摩尔分数达63.66%,表明整个电解系统气密性良好。此外,制得的气体能够满足电子回旋共振离子源提供18O重离子束的实验要求。     

Ray Tracing Study of Electromagnetic Ion Cyclotron Waves Associated with Bi-Ion Frequencies

Ray tracing study of electromagnetic ion cyclotron （EMIC） waves is conducted based on a realistic plasma density model. The simulation result shows that EMIC waves propagate away from the equatorial source region to higher latitudes basically along geomagnetic field lines, and are reflected at the region where their frequency matches the local bi-ion frequency. H＋ band suffers H＋-He＋ bi-ion frequency reflection at lower latitudes, whereas He＋ band suffers He＋-O＋ bi-ion frequency reflection at higher latitudes. Moreover, the concentration of heavy ions slightly affects the bi-ion frequencies and then slightly determines the reflection location of ray paths of EMIC waves. The current results present the first detailed study on the propagation characteristics of EMIC waves associated with bi-ion frequencies.     

电解法制备高纯度墙^18O2

采用自行设计制造的石英玻璃电解装置，以重氧重水为原料，通过碱性介质电解法进行了^18O气体的制备，在原料重氧重水^18O的摩尔分数〉80％条件下，最终制得^18O气体中^18O2摩尔分数达63．66％，表明整个电解系统气密性良好。此外，制得的气体能够满足电子回旋共振离子源提供^18O重离子束的实验要求。