SSC-LINAC重离子RFQ动力学模拟与研究

采用多粒子跟踪程序BEAMPATH 对SSC-LINAC 重离子RFQ 直线加速器进行动力学模拟,分别对RFQ 的接受度、高频特性、束流稳定性、空间电荷效应等进行了分析。该RFQ具有很大的纵向接受度,有利于束流在RFQ中的传输;高频特性研究表明,翼间电压设定在理论值以上时,该RFQ都能保持较好的束流特性;束流稳定性分析结果表明,该RFQ具有很大的束流失配容忍度;空间电荷效应研究表明,当束流强度低于0.5 mA时,束流传输不受影响。综合研究结果表明,53.667 MHz重离子RFQ具有较好的动力学特性,满足SSC-LINAC直线加速器的设计要求。The RFQ beam dynamics of a heavy ion linac was investigated in this paper and the BEAMPATH code was employed in this study. The main research was focused on the beam performances depending on longitudinal acceptance, RF properties, beam instability and space charge effect. The RFQ has large longitudinal acceptance in design, which brings the beam performances well. In the RF parameter study, the beam can keep good transmission in the acceleration even the vane voltage is larger than the theoretical value. It is also shown that the RFQ has a large robustness for the mismatch of the input beam by the analysis of the beam instability.Furthermore, the beam evolution is independent on the space charge effect when the beam current is less than 0.5 emA. The preliminary analysis of the beam dynamics shows that the 53.667 MHz heavy ion RFQ has a promising performance, which meets the requirements of SSC-LINAC.     

HIAF-BRing的双向涂抹注入模拟

BRing是HIAF工程的主加速器,其设计流强为每个脉冲内的粒子数1×1011个（238U34+）,为了达到此设计流强,注入增益应达到88倍以上。BRing采用了双向涂抹注入方案,其满足BRing的注入增益要求,同时具有注入时间短和累计束分布较均匀而减小了空间电荷效应的特点。双向涂抹注入方案利用水平和垂直两组凸轨磁铁以及倾斜的静电偏转板,在水平相空间和垂直相空间内同时进行涂抹。为了检验双向涂抹注入方案能否达到BRing的设计要求,利用ORBIT程序对双向涂抹注入过程进行了模拟,模拟结果显示,在单次双向涂抹注入113圈的情况下,注入效率为97.7%,注入增益达到110.3倍,满足了BRing流强要求。累积束的分布相对均匀,空间电荷效应引起的工作点漂移约为-0.02,粒子因共振损失风险很小。针对注入束流偏角、切割板角度、工作点偏差和Bump延时等不同注入参数进行了误差分析,结果显示BRing的双向涂抹注入效率对注入参数偏差的容忍度较高。BRing is the main accelerator of High Intensity heavy Ion Accelerator Facility(HIAF) and its design current is 1×1011 particles per pulse (238U34+). To accumulate beams up to the design current, the injection gain has to reach 88. Two planes painting injection scheme is proposed for BRing. This scheme uses a tilted electrostatic septum and 8 bump magnets to paint beams into horizontal and vertical phase space simultaneously. It can inject enough beams into the ring in a short time and paint beams uniformly. The injection process is simulated using ORBIT code and 113 turns is injected into BRing with an injection efficiency of 97.7% which meets the requirement for beam current of BRing. The accumulated beams are distributed uniformly in transverse and hence have a little tune shift of -0.02 which reduces the risk of beam loss due to the resonance. Errors of injection parameters are analysed and the result shows two planes painting injection scheme has a high tolerance for errors of injection parameters.     

CSR-LINAC IH-RFQ的高频电磁设计

中国科学院近代物理研究所在CSR-LINAC项目中设计了一台108.48 MHz的IH型RFQ直线加速器。该RFQ可以将质荷比为3~7的离子从4 keV/u加速到300 keV/u。在完成束流动力学设计的基础上,主要针对RFQ腔体的高频电磁设计展开了研究,同时利用了电磁场仿真和束流动力学模拟来研究腔体的四极场不平整度和二极场及其动力学影响。未经调谐的情况下,腔体的谐振频率为108.15 MHz,腔体空载品质因子Q₀为5 910,腔体功耗为123 kW。通过在支撑板两端增加底切的设计,将腔体的四极场不平整度由-21%~ 12%优化至±2.5%,满足了束流动力学要求。腔体的二极场为-3%~ -2.2%,使得束流在垂直方向小幅振荡,RFQ的垂直方向接受度减小5%。为了保证功率馈入时反射较小,将耦合器设置在临界耦合状态,耦合面积为940 mm2。为了补偿腔体的频率偏差和漂移,设计了调谐量分别为707和132 kHz的固定调谐器和可动调谐器。The 108.48 MHz IH type RFQ for CSR-LINAC project is under design at Institute of Modern Physics, Chinese Academy of Sciences. This RFQ can accelerate heavy ions with mass to charge ratio of 3~7 from 4 keV/u to 300 keV/u. According to the beam dynamics requirement, the RF structure design has been finished. The quadrupole field unflatness and dipole field of the cavity were studied by electromagnetic simulation and beam dynamics simulation. The frequency of the cavity without tuning is 108.15 MHz, the Q₀ of the cavity is 5910, and the RF power loss is 123 kW. The quadrupole field unflatness of ±2.5%,which was -21%~12% before optimizing, is achieved to meet dynamics requirement through the undercuts in cavity supporters. The dipole field of -3%~ -2.2% causes the oscillation of the beam center and acceptance reduction of 5%. The power coupler must be in critical coupling state with the coupling area of 940 mm2 for minimum reflection coefficient. The tuners, consist of coarse and fine tuners with frequency shift of 707 and 132 kHz respectively, is used for tuning of frequency deviation of the cavity.     

（Ce，Cu）：LiNbO3晶体非挥发全息记录理论研究与优化

根据双中心带输运模型，对（Ce，Cu）：LiNbO3晶体双中心非挥发全息记录进行了理论研究与优化。推导了（Ce，Cu）：LiNbO3晶体的微观参量，采用数值方法通过严格求解模拟双中心带输运方程来模拟全息记录过程。分析了记录过程中，记录与敏化光强、Ce和Cu掺杂浓度以及晶体微观参量对（Ce，Cu）：LiNbO3晶体双中心全息记录的影响。发现（Ce，Cu）：LiNbO3晶体非挥发全息记录中实现高衍射效率与固定效率的主导因素是深中心Cu，在记录过程中，深中心Cu建立起了很强的空间电荷场。数值模拟的结果经过实验验证，最高饱和与固定衍射效率别为60．5％和53．8％。     

Red Laser-Induced Domain Inversion in MgO-Doped Lithium Niobate Crystals

A laser beam at wavelength 647nm is focused on a sample of 5mol% MgO-doped lithium niobate crystal for domain inversion by a conventional external electric field. In this case, a reduction of 36% in the electric field required for domain nucleation （nucleation field） is observed. To the best of our knowledge, it is the longest wavelength reported for laser-induced domain inversion. This extends the spectrum of laser inducing, and the experimental results are helpful to understand the nucleation dynamics under laser illumination. The dependence of nucleation fields on intensities of laser beams is analysed in experiments.     

樟脑基苯基硫脲类化合物的合成及生物活性研究

以D-(+)-樟脑为原料,经肟化、还原得到樟脑胺,再与取代苯基异硫氰酸酯反应,合成得到10个未见文献报道的樟脑基苯基硫脲化合物(5a~5j),其结构通过FT IR、1H NMR、13C NMR和ESI-MS表征确认。初步生物活性测试表明,目标化合物在浓度50mg/L下对5种供试植物病原菌显示不同程度的抑菌活性,其中化合物5f(R=m-OCH3)和5d(R=p-CH3)对苹果轮纹病菌(Physalospora piricola)和番茄早疫病菌(Cercospora arachidicola)的抑制率分别达83.9%和82.2%;在浓度100mg/L下,化合物5i(R=p-Br)对油菜(Brassica campestris)胚根生长的抑制率为60.2%。     

新型去氢枞酸基磺酰胺类化合物的合成及其生物活性

去氢枞酸与SOCl2反应制得去氢枞酸酰氯(2);芳磺酰氯与乙二胺经N-酰化反应制得N-芳磺酰基乙二胺(4a~4k);在DMAP催化下,2分别与4a~4k经N-酰化反应合成了11个新型的去氢枞酸基磺酰胺类化合物(5a~5k),其结构经1H NMR,13C NMR,IR和ESI-MS表征。生物活性测试结果表明,在用药量为50μg·mL-1时,5a~5k对黄瓜枯萎病菌、苹果轮纹病菌、番茄早疫病菌、花生褐斑病菌和小麦赤霉病菌有一定的抑菌活性,其中去氢枞酸基间甲基苯磺酰胺(5c)对番茄早疫病菌的杀菌活性最佳,抑制率为73.6%;在用药量为100μg·mL-1时,大部分化合物对油菜的胚根生长有一定抑制作用,其中去氢枞酸基对甲氧基苯磺酰胺(5d)的抑菌活性最佳,抑菌率为57.1%。     

储存环HIAF-SRing等时性模式的非线性磁场影响研究

高精度环形谱仪SRing（Spectrometer Ring）是强流重离子加速器装置（HIAF）的重要组成部分,其等时性模式为远离β稳定线的短寿命原子核质量和寿命的精确测量提供国际领先的科研条件。为了扩大短寿命原子核质量测量精度和范围,SRing等时性模式设计了两种光学:γ_t=1.43和1.67。质量分辨是衡量等时性储存环的最重要参数。二极磁铁的高阶场以及磁铁的边缘场能强烈地引起束流光学高阶畸变,对质量分辨产生影响,因此需要高极磁铁对其进行校正。介绍了SRing等时性模式的线性计算,对非线性磁场的影响进行了详细研究。应用六极磁铁和八极磁铁对非线性场和发射度的影响进行了校正后,离子的循环时间标准偏差σ（T）/T达到3.5×10-7,质量分辨△m/m达到1×106。The isochronous mode of the Spectrometer Ring at the High Intensity heavy-ion Accelerator Facility (HIAF) project in China offers the capacity of measuring the mass and half-life of short-lived nuclides. The transition energy settings of the SRing are 1.43 and 1.67, which have been calculated in the same injection scheme. The resolution of mass or revolution time is the most important parameter of the isochronous mode design of a storage ring. The nonlinear magnetic field errors, including high-order magnet field of dipole, fringe field of magnets, have strongly effect to the resolution of revolution time. High-order corrections are required to improve the resolution of revolution time and mass. In this paper, the SRing linear isochronous optical were shown. The influence of nonlinear magnetic field errors on the revolution time resolving power were investigated. With 3 sextupole families and 1 octupole family corrections, the relative variation of revolution time reaches 4.6×10-7 with the momentum spread of ±0.2%. The relation of the relative standard revolution time deviation σ(T)/T and revolution turns was researched. With corrections of high-order isochronous condition and emittance influence by 3 sextupole families and 1 octupole family, one can reach a resolution of up to σ(T)/T=3.5×10-7, which corresponds to the mass resolution of △m/m=1×106.     

透镜自重变形引起波像差的有限元分析

在用大口径、长焦距平行光管模拟激光远场特性时,其光组透镜在重力作用下的变形不能忽略,为了分析对出射光束质量的影响,采用有限元分析软件“ANSYS”建立了平行光管光组中声400mm平凸透镜的有限元模型,给出一种分析透镜轴向变形引起的波像差的方法,在不同工况下,计算了平凸透镜在重力作用下轴向变形的峰谷值和均方根值,对轴向变形量均方根值最小工况画出了透镜表面变形的等值线图,计算了声350mm通光口径内的波像差峰谷值和均方根值,对平行光管光组的波像差做出估计,验证了设计的合理性。     

含天然蒎烯结构的4-酰基-3-氨基-1,2,4-三唑-硫醚衍生物的合成、抑菌活性、三维定量构效关系及分子对接研究（英文）

为了探寻以天然可再生资源为基础的生物活性分子,设计并合成了24个新型含天然蒎烯结构的4-酰基-3-氨基-1,2,4-三唑-硫醚衍生物,通过IR,~1H NMR,¹³C NMR,ESI-MS和元素分析对所有目标化合物的结构进行了表征.初步的离体抑菌活性测试结果表明,在质量浓度为50μg/mL时,目标化合物对测试的8种植物病原菌表现出一定的抑菌活性,其中有4个化合物对苹果轮纹病菌有优良的抑菌活性,远优于阳性对照百菌清;2个化合物对花生褐斑病菌有良好的抑制活性,远优于阳性对照百菌清.使用比较分子力场分析法(CoMFA)对目标化合物的抗苹果轮纹病菌活性进行了初步的三维定量构效关系(3D-QSAR)分析,建立了一个合理的3D-QSAR模型(r~2=0.961,q~2=0.613).此外,分子对接结果表明,目标化合物诺卜醇基4-(4’-氟苯甲酰基)-3-氨基-1,2,4-三唑-硫醚(5k)在琥珀酸脱氢酶(SDH)活性口袋的结合模式与商品杀菌剂萎锈灵相似.