Lanzhou all permanent ECR ion source No.1 - LAPECR1

The Lanzhou All Permanent magnet ECR ion source NO. 1 (LAPECR1) is the first all permanent magnet multiple ECRIS made in IMP. This ECRIS is running at 14.5GHz and can provide intense low charge state ion beams (varying from several to hundreds of e mu A) or medium charge state ion beams (varying from several to tens of e mu A). The size of source body is circle divide 102mmx296mm, the compactness and economical features enable the source suitable to be put on a HV platform or equipped by a small laboratory. This article gives the main parameters of the ion source.

Preliminary results of the updated LECR2 source-LECR2M

The Latest developed LECR2M (Lanzhou ECR No. 2 Modified) source is the updated one of LECR2 (Lanzhou ECR No. 2) source at IMP. It has been assembled on the low energy ion beam experimental platform to produce MCI beams for atomic physics and material physics experimental research. In our updating program, the structure of injection and extraction components has been modified to make the source structure more simple and effective. The hexapole magnet has also been replaced by a new hexapole magnet with higher radial field and larger inner diameter. With this updating, stronger magnetic field confinement of the ECR plasma is possible and better base vacuum condition is also achieved. LECR2M was designed to be operated at 14.5GHz. During the preliminary test, 1.3emA O6+ beam was extracted with the injected rf power of 1.1kW. The source has been used to deliver intense MCI beams for different experiments. After some discussion of the main features of this newly updated source, some of the typical commissioning test results of LECR2M will be presented.

A compact proton source for space simulation

A compact proton beam source for space simulation has been developed. A compact structure was designed in order to meet the special requirements of miniaturization. Some particular means have been adopted for improving the proton portion and beam transmission at a long distance. The experimental results showed that 8mA/80keV proton beam can be successfully obtained from this source at about 700W input microwave power.

Intense beam production of highly charged heavy ions by the superconducting electron cyclotron resonance ion source SECRAL (invited)

There has been increasing demand to provide higher beam intensity and high enough beam energy for heavy ion accelerator and some other applications, which has driven electron cyclotron resonance (ECR) ion source to produce higher charge state ions with higher beam intensity. One of development trends for highly charged ECR ion source is to build new generation ECR sources by utilization of superconducting magnet technology. SECRAL (superconducting ECR ion source with advanced design in Lanzhou) was successfully built to produce intense beams of highly charged ion for Heavy Ion Research Facility in Lanzhou (HIRFL). The ion source has been optimized to be operated at 28 GHz for its maximum performance. The superconducting magnet confinement configuration of the ion source consists of three axial solenoid coils and six sextupole coils with a cold iron structure as field booster and clamping. An innovative design of SECRAL is that the three axial solenoid coils are located inside of the sextupole bore in order to reduce the interaction forces between the sextupole coils and the solenoid coils. For 28 GHz operation, the magnet assembly can produce peak mirror fields on axis of 3.6 T at injection, 2.2 T at extraction, and a radial sextupole field of 2.0 T at plasma chamber wall. During the commissioning phase at 18 GHz with a stainless steel chamber, tests with various gases and some metals have been conducted with microwave power less than 3.5 kW by two 18 GHz rf generators. It demonstrates the performance is very promising. Some record ion beam intensities have been produced, for instance, 810 e mu A of O7+, 505 e mu A of Xe20+ 306 e mu A of Xe27+, and so on. The effect of the magnetic field configuration on the ion source performance has been studied experimentally. SECRAL has been put into operation to provide highly charged ion beams for HIRFL facility since May 2007.

关于强流ECR质子源氢等离子体发射光谱的诊断研究；OES diagnostics of H_2 plasma in an intense ECR proton source

本文通过发射光谱诊断方法,用H_2等离子体的辐射碰撞模型对连续溃入的微波功率和全永磁磁场约束下产生高密度的H_2等离子体进行光谱诊断,计算出一定放电条件下(微波功率200-700 W,压强0-2 Pa)H~+的密度为1010-1011 cm~(-3),另外讨论了实验中观察到的Balmer系氢原子发射光谱强度随放电条件的变化规律。

The study of helicon plasma source

Helicon plasma source is known as efficient generator of uniform and high density plasma. A helicon plasma source was developed for investigation of plasma neutralization and plasma lens in the Institute of Modern Physics in China. In this paper, the characteristics of helicon plasma have been studied by using Langmuir four-probe and a high argon plasma density up to 3.9x10(13) cm(-3) have been achieved with the Nagoya type III antenna at the conditions of the magnetic intensity of 200 G, working gas pressure of 2.8x10(-3) Pa, and rf power of 1200 W with a frequency of 27.12 MHz. In the experiment, the important phenomena have been found: for a given magnetic induction intensity, the plasma density became greater with the increase in rf power and tended to saturation, and the helicon mode appeared at the rf power between 200 and 400 W.

New development of advanced superconducting electron cyclotron resonance ion source SECRAL (invited)

Superconducting electron cyclotron resonance ion source with advance design in Lanzhou (SECRAL) is an 18-28 GHz fully superconducting electron cyclotron resonance (ECR) ion source dedicated for highly charged heavy ion beam production. SECRAL, with an innovative superconducting magnet structure of solenoid-inside-sextupole and at lower frequency and lower rf power operation, may open a new way for developing compact and reliable high performance superconducting ECR ion source. One of the recent highlights achieved at SECRAL is that some new record beam currents for very high charge states were produced by 18 GHz or 18+14.5 GHz double frequency heating, such as 1 e mu A of Xe-129(43+), 22 e mu A of Bi-209(41+), and 1.5 e mu A of Bi-209(50+). To further enhance the performance of SECRAL, a 24 GHz/7 kW gyrotron microwave generator was installed and SECRAL was tested at 24 GHz. Some promising and exciting results at 24 GHz with new record highly charged ion beam intensities were produced, such as 455 e mu A of Xe-129(27+) and 152 e mu A of Xe-129(30+), although the commissioning time was limited within 3-4 weeks and rf power only 3-4 kW. Bremsstrahlung measurements at 24 GHz show that x-ray is much stronger with higher rf frequency, higher rf power. and higher minimum mirror magnetic field (minimum B). Preliminary emittance measurements indicate that SECRAL emittance at 24 GHz is slightly higher that at 18 GHz. SECRAL has been put into routine operation at 18 GHz for heavy ion research facility in Lanzhou (HIRFL) accelerator complex since May 2007. The total operation beam time from SECRAL for HIRFL accelerator has been more than 2000 h, and Xe-129(27+), Kr-78(19+), Bi-209(31+), and Ni-58(19+) beams were delivered. All of these new developments, the latest results, and long-term operation for the accelerator have again demonstrated that SECRAL is one of the best in the performance of ECR ion source for highly charged heavy ion beam production. Finally the future development of SECRAL will be presented.

The Compact Pulsed Hadron Source: A Design Perspective

During the past. decades, large-scale national neutron sources have been developed in Asia, Europe, and North America. Complementing such efforts, compact hadron beam complexes and neutron sources intended to serve primarily universities and industrial institutes have been proposed, and some have recently been established. Responding to the demand in China for pulsed neutron/proton-beam platforms that are dedicated to fundamental and applied research for users in multiple disciplines from materials characterization to hadron therapy and radiography to accelerator-driven sub-critical reactor systems (ADS) for nuclear waste transmutation, we have initiated the construction of a compact, yet expandable, accelerator complex-the Compact Pulsed Hadron Source (CPHS). It consists of an accelerator front-end (a high-intensity ion source, a 3-MeV radio-frequency quadrupole linac (RFQ), and a 13-MeV drift-tube linac (DTL)), a neutron target station (a beryllium target with solid methane and room-temperature water moderators/reflector), and experimental stations for neutron imaging/radiography, small-angle scattering, and proton irradiation. In the future, the CPHS may also serve as an injector to a ring for proton therapy and radiography or as the front end to an ADS test facility. In this paper, we describe the design of the CPHS technical systems and its intended operation.

八单元一维位置灵敏雪崩室

In the experiment of nuclear reaction, it is important to measure the mass, charge, energy and emitted direction of particles. For multiparameter measurement, we must use a detector or a group of detectors which can give the time, energy, and position information. The Large Area position sensitive Ionization Chamber(LAIC) is one of the eight experiment terminals of HIRFL. It is built for researching nuclear reactions from low energy to intermediate energy. It is an excellent equipment for energy measurements and atomic number identification of emitted fragments in this energy region. It is also designed to give the time and position information of the emitted fragments by itself. Obviously, an IC can not supply a good timing signal. Moreover, the mechanical installation is different from the original design by some other reasons. In this case, it is not enough to obtain the correct direction information of the emitted fragments. To obtain good timing signals and the correct direction information, some modifications must be made. It is well known that a PPAC can give us excellent timing signals. It also can be easily built as a position sensitive detector. For this reason, a specially designed PPAC is installed in the entrance of the LAIC. For the different purposes, two types of PPACs were designed and tested. Both are OCTPSACs (OCTunit one dimension Position Sensitive Avalanche Counter). In this paper, both OCTPSACs will be introduced. Based on the requirements of the LAIC, the OCTPSACs consist of eight position sensitive PPACs. Each PPAC has an anode and a cathode. In both cases, the sizes are same. But different type of cathodes are used. In one type of OCTPSAC, its cathode is made of wire plane. It consists of gold-plated tungsten wires with the diameter of 20μm, spaced 0.5 mm apart from each other. The anode is a mylar foil which was evaporated by gold layer with the thickness of 50μg/cm~2 mounted on a printed plate in the shape of rectangle. the thickness of mylar foil is 1.5μm. The gap between anode and cathode is 3mm. The performance of the OCTPSAC has been tested by using a ~(252)Cf source in flowing isobutylene gas at the pressure of 3.4mb. The intrinsic time resolution of 289ps and position resolution of 2 mm have been obtained. In another type of OCTPSAC, the cathode is made of mylar foil, which is composed of gold strip by vacuume evaporation method with a special mask on the mylar foil. The thickness and the width of the gold strip is 50μg/cm~2 and 1.7mm. The strips are spaced 0.3 mm apart from each other. The anode is the same as the former type. We have obtained the time resolution of 296ps and position resolution of 2mm by using ~(241)Am-a source when the gas pressure is 6 mb and high voltage is 600V. The working gas is heptane

Photo-induced reactions in the ion-molecule complex Mg+-OCNC2H5

Ion - molecule complexes of magnesium cation with ethyl isocyanate were produced in a laser- ablation supersonic expansion nozzle source. Photo- induced reactions in the 1: 1 complexes have been studied in the spectral range of 230 - 410 nm. Photodissociation mass spectrometry revealed the persistent product Mg+ from nonreactive quenching throughout the entire wavelength range. As for the reactive channels, the photoproducts, Mg+OCN and C2H5+, were produced only in the blue absorption band of the complex with low yields. The action spectrum of Mg+(OCNC2H5) consists of two pronounced peaks on the red and blue sides of the Mg+ 3(2)P <-- 3(2)S atomic transition. The ground state geometry of Mg+ - OCNC2H5 was fully optimized at B3LYP/6- 31 - G** level by using GAUSSIAN 98 package. The calculated absorption spectrum of the complex using the optimized structure of its ground state agrees well with the observed action spectrum. Photofragment branching fractions of the products are almost independent of the photolysis photon energy for the 3P(x,y,z) excitations. The very low branching ratio of reactive products to nonreactive fragment suggests that evaporation is the main relaxation pathway in the photo- induced reactions of Mg+ (OCNC2H5). (C) 2003 American Institute of Physics.

Microspheres and microcapsules, a survey of manufacturing techniques: Part III: Solvent evaporation

A methodological survey of microsphere formation and microencapsulation techniques based on solvent extraction/evaporation techniques is presented. Thus, basic features of solvent extraction and solvent evaporation processes, including droplet formation, droplet/particle stabilization, and solvent removal, are outlined. Preparation of a wide range of microspherical and microcapsular products based on biodegradable polyesters, polysaccharides, and nonbiodegradable polymers are discussed. Dependence of microcapsule characteristics on manufacturing parameters, as well as performance evaluation of microspherical and microcapsular products, are also briefly covered.

A QUANTITATIVE ASSESSMENT OF SOURCE CONTRIBUTIONS TO INHALABLE PARTICULATE MATTER POLLUTION IN METROPOLITAN BOSTON

In this paper, source apportionment techniques are employed to identify and quantify the major particle pollution source classes affecting a monitoring site in metropolitan Boston, MA. A Principal Component Analysis (PCA) of paniculate elemental data allows the estimation of mass contributions for five fine mass panicle source classes (soil, motor vehicle, coal related, oil and salt aerosols), and six coarse panicle source classes (soil, motor vehicle, refuse incineration, residual oil, salt and sulfate aerosols). Also derived are the elemental characteristics of those source aerosols and their contributions to the total recorded elemental concentrations (i.e. an elemental mass balance). These are estimated by applying a new approach to apportioning mass among various PCA source components: the calculation of Absolute Principal Component Scores, and the subsequent regression of daily mass and elemental concentrations on these scores.

The characteristics of land cover and macroscopical ecology changes in the source region of three rivers in Qinghai-Tibet plateau during last 30 years

We obtained four phases of land cover spatial data sets by interpreting MSS images of middle and late 1970s and three phases of TM images of late 1980s, 2004 and 2008 based on field investigation in Three Rivers' Source Region. We analyzed the temporal and spatial characteristics of land cover and macro ecological changes in Three Rivers' Source Region in Qinghai-Tibet plateau since middle and late 1970s. Indicated by land cover condition index change rate and land cover change index, land cover and macroscopical ecological condition degenerated (7090 period Zc -0.63, LCCI -0.58)-obviously degenerated (9004 period, Zc -0.94, LCCI -1.76)-slightly meliorated (0408 period, Zc 0.06, LCCI 0.33). This course was jointly driven by climate change, grassland stocking pressure and implement of ecological construction project.

A simple selenium source to synthesize CdSe via the two-phase thermal approach

A novel selenium source was developed to synthesize the size-controlled CdSe nanocrystals with relatively narrow size distribution successfully in a two-phase thermal approach. A highly reactive and aqueous soluble selenium source was provided by the reduction of selenite, and in this route the size of the nanocrystals can be adjusted by the reaction temperature and time. The size, crystalline structure and optical characteristics of these nanocrystals were investigated by transmission electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, UV-vis spectroscopy, and photoluminescence spectroscopy. The influence factors for this approach were also discussed.