共查询到19条相似文献,搜索用时 906 毫秒
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两种气体离子源氮离子注入细菌的诱变效应比较 总被引:2,自引:0,他引:2
低能离子注入作为一种新的诱变育种手段已经得到广泛的应用.对考夫曼气体离子源和双潘宁气体离子源氮离子注入凝结芽孢杆菌的效果进行比较.经研究发现,在相同的引出电压下,考夫曼气体离子源注入的菌体到第三代的遗传稳定性要比双潘宁气体离子源注入的菌体高30%,但突变平均幅度要低2%,以此为依据可以根据不同诱变需要选择合适的离子源. 相似文献
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一、问题的提出研制强流离子注入机的关键,除了要有强流离子源外,主要是克服束流传输过程中的空间电荷效应问题。为此,我们研究非线性强流加速管,来克服强流束在加速管中的空间电荷效应。 相似文献
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ECR(电子回旋共振)离子源是产生稳定的强流多电荷态离子束流最有效装置.全永磁ECR离子源因其独特的特点为很多中小型多电荷态离子束流实验平台与离子注入机等系统所采用,为后者产生重复性好、稳定性强的多电荷态离子束流.本文着重论述了中国科学院近代物理研究所研制的几台全永磁多电荷态ECR离子源及其特性与典型性能,如能产生强流高电荷态离子束流的高性能全永磁离子源LAPECR2,能产生强流中低电荷态离子束流的LAPECR1,能产生多电荷态重金属离子柬流的LAPECRl-M等.这些性能稳定的离子源为提高近代物理研究所相关试验平台的性能提供了关键的束流品质保障. 相似文献
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M.M. Abdelrahman F.W. Abdelsalam 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2011,269(15):1761-1766
The present work investigates the computer analysis of the ion beam properties produced by a Freeman type system. The extraction for such system is composed of four electrodes that permit to keep a fixed output energy by means of two accelerating gaps and one decelerating gap. The latter allows reducing the beam divergence angle. The combination of the acceleration/deceleration sections provides to keep a low beam emittance at the source outlet. The simulation of single charged argon ion trajectories for a plasma concave of curvature 4 mm was first studied with and without space charge effect using acceleration/deceleration extraction system with the aid of the SIMION computer program. The voltage applied to the accelerating electrode was optimized to accomplish the suitable ion trajectories without hitting the extraction electrode. Then, two additional studies were performed: the influence of the acceleration voltage and extraction voltage on the beam emittance and beam diameter; and the effect of the extraction gap width (distance between the plasma emission surface and the acceleration electrode) on the shape of the ion beam envelope and the position of the ion beam waist. Last, the influence of the space charge on the ion beam envelope was also investigated. 相似文献
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John J. Barnard 《Journal of Fusion Energy》1998,17(3):223-225
A review of nonneutral plasma science issues for heavy ion drivers is presented. The requirements on transverse and longitudinal focusing at the target lead to constraints on the 6D phase space. Mechanisms which act to prevent focusability, including emittance growth, space charge and instabilities are discussed. Experiments which have explored and validated our understanding of beam transport and focusability of space-charge dominated heavy ion beams are described. 相似文献
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中国散裂中子源(CSNS)直线加速器至快循环同步加速器(RCS)的束流输运线(LRBT)传输80 MeV H-束流至RCS注入点,由于较小的束流发射度和较高的峰值流强,空间电荷效应在LRBT中的影响非常显著,是引起LRBT中发射度增长和束流损失的主要因素,也是LRBT优化设计中的重要问题。文章利用TRACE 3-D程序进行带有空间电荷效应的twiss参量和消色散匹配,比较研究LRBT不同聚焦结构和不同初始束流分布条件下发射度的增长情况。对于采用Triplet结构作为标准单元的结构,研究发现,通过优化LRBT前端匹配段能有效控制发射度的增长。多粒子模拟跟踪结果表明,峰值流强为15 mA时,现有物理孔径下基本无束流损失发生。对LRBT上散束器的参数和位置进行了优化设计,可减少动量散度和中心能量抖动,优化RCS注入束流参数。 相似文献
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放射性核束在生物医学中的应用 总被引:3,自引:0,他引:3
不同衰变方式和半衰期的放射性核束在生物医学领域有不同应用。本文评述了自20世纪70年代中期美国LBL实验室首次产生高能放射性核束以来,世界范围内利用放射性核束开展的生物医学应用研究情况,并提出了一些可在兰州放射性束流线(RIBLL)和将要建成的兰州重离子加速器冷却储存环(HIRFL-CSR)装置上进行的生物医学应用研究的设想。 相似文献
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T. T. Inamura M. Koizumi K. Morita
A. Yoshida
M. Takami
T. Ishizuka
I. Nakamura M. NakaokaT. Murayama
I. Sugai
M. Azuma
H. KatsuragawaK. Shimomura
S. Matsuki
A. Iivonen
K. Valli 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》1992,70(1-4):226-232The velocity distribution of an ion beam from an IGISOL ion guide isotope separator on-line was measured directly by means of laser spectroscopy and compared with that estimated from the mass spectrum. The latter is found to be more than two times broader than the former. The emittance of the ion beam as well as its velocity spread was also studied with laser beams. It is noted that the emittance affects the mass spectrum considerably, resulting in a poor resolving power for the net velocity spread. Laser spectroscopy of radioactive atoms with the IGISOL, especially of refractory elements, seems promising. 相似文献
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V. Toivanen O. Steczkiewicz O. Tarvainen T. Ropponen J. Ärje H. Koivisto 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(9):1508-1516
The results of a series of measurements studying the possibility to use neutral gas feeding into the beam line as a way to improve the quality of the heavy ion beams produced with an electron cyclotron resonance ion source (ECRIS) are presented. Significant reduction of the beam spot size and emittance can be achieved with this method. The observed effects are presumably due to increased space charge compensation degree of the ion beam in the beam line section between the ion source and the analyzing magnet. This is the region where the neutral gas was injected. It is shown that the effects are independent of the ion source tuning. Transmission measurements through the beam line and K-130 cyclotron have been carried out to study the effects of improved ion beam quality to the transmission efficiency. 相似文献