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1.
One kind of instantaneous electron beam emittance measurement system based on the optical transition radiation principle and double imaging optical method has been set up. It is mainly adopted in the test for the intense electron-beam produced by a linear induction accelerator. The system features two characteristics. The first one concerns the system synchronization signal triggered by the following edge of the main output waveform from a Blumlein switch. The synchronous precision of about 1 ns between the electron beam and the image capture time can be reached in this way so that the electron beam emittance at the desired time point can be obtained. The other advantage of the system is the ability to obtain the beam spot and beam divergence in one measurement so that the calculated result is the true beam emittance at that time, which can explain the electron beam condition. It provides to be a powerful beam diagnostic method for a 2.5 kA, 18.5 MeV, 90 ns (FWHM) electron beam pulse produced by Dragon I. The ability of the instantaneous measurement is about 3 ns and it can measure the beam emittance at any time point during one beam pulse. A series of beam emittances have been obtained for Dragon I. The typical beam spot is 9.0 mm (FWHM) in diameter and the corresponding beam divergence is about 10.5 mrad.  相似文献   

2.
One kind of instantaneous electron beam emittance measurement system based on the optical transition radiation principle and double imaging optical method has been set up. It is mainly adopted in the test for the intense electron-beam produced by a linear induction accelerator. The system features two characteristics. The first one concerns the system synchronization signal triggered by the following edge of the main output waveform from a Blumlein switch. The synchronous precision of about 1 ns between the electron beam and the image capture time can be reached in this way so that the electron beam emittance at the desired time point can be obtained. The other advantage of the system is the ability to obtain the beam spot and beam divergence in one measurement so that the calculated result is the true beam emittance at that time, which can explain the electron beam condition. It provides to be a powerful beam diagnostic method for a 2.5 kA, 18.5 MeV, 90 ns (FWHM) electron beam pulse produced by Dragon I. The ability of the instantaneous measurement is about 3 ns and it can measure the beam emittance at any time point during one beam pulse. A series of beam emittances have been obtained for Dragon I. The typical beam spot is 9.0 mm (FWHM) in diameter and the corresponding beam divergence is about 10.5 mrad.  相似文献   

3.
A new generation electron cooler has started operation in the heavy ion synchrotron CSRm which is used to increase the intensity of heavy ions. Transverse cooling of the ion beam after horizontal multi-turn injection allows beam accumulation at the injection energy. After optimization of the accumulation process an intensity increase in a synchrotron pulse by more than one order of magnitude has been achieved. In given accumulation time interval of 10 seconds, 108 particles have been accumulated and accelerated to the final energy. The momentum spread after accumulation and acceleration in the 10-4 range has been demonstrated in six species of ion beams. Primary measurements of accumulation process varying with electron energy, electron beam current, electron beam profile, expansion factor and injection interval have been performed. The lifetimes of ion beams in the presence of electron beams were roughly measured with the help of DCCT signal.  相似文献   

4.
The possibility of an electron beam exciting surface plasmons in conducting metal is discussed in this paper.A planar perfect-structure with subwavelength holes is proposed.The phenomenon that mimicking surface plasmon waves can be excited and amplified by an electron beam is proved theoretically and numerically.The mechanism of transmission through a subwavelength hole array is exploited to enhance the interaction between the electron beam and the mimicking surface plasmons.  相似文献   

5.
An electron beam is obtained using laser wakefield electron accelerator, and converted into a γ-ray source after undergoing bremsstrahlung radiation in a dense material. A quasi-monoenergetic structure is observed when the length of the plasma channel was modified. The structure has a 58-MeV peak energy, 15mrad (full-width at half-maximum) divergence angle, and 340-pC charge. The γ-ray source generated by this high-quality electron beam is brighter and has higher spatial and temporal resolutions than other conventional sources. A γ-ray radiography demonstrational experiment is performed. Pictures of a ball with different layers made of different materials are taken. The results show a clear structure and density resolution.  相似文献   

6.
Using the ellipsoidal cavity model, the quasi-monoenergetic electron output beam in laser-plasma interaction is described. By the cavity regime the quality of electron beam is improved in comparison with those generated from other methods such as periodic plasma wave field, spheroidal cavity regime and plasma channel guided acceleration. Trajectory of electron motion is described as hyperbolic, parabolic or elliptic paths. We find that the self-generated electron bunch has a smaller energy width and more effective gain in energy spectrum. Initial condition for the ellipsoidal cavity is determined by laser-plasma parameters. The electron trajectory is influenced by its position, energy and cavity electrostatic potential.  相似文献   

7.
Commissioning of electron cooling in CSRm   总被引:1,自引:0,他引:1  
A new generation electron cooler has started operation in the heavy ion synchrotron CSRm which is used to increase the intensity of heavy ions. Transverse cooling of the ion beam after horizontal multi-turn injection allows beam accumulation at the injection energy. After optimization of the accumulation process an intensity increase in a synchrotron pulse by more than one order of magnitude has been achieved. In given accumulation time interval of 10 seconds, 108 particles have been accumulated and accelerated to the final energy. The momentum spread after accumulation and acceleration in the 10-4 range has been demonstrated in six species of ion beams. Primary measurements of accumulation process varying with electron energy, electron beam current, electron beam profile, expansion factor and injection interval have been performed. The lifetimes of ion beams in the presence of electron beams were roughly measured with the help of DCCT signal.  相似文献   

8.
The electron proton (e-p) instability has been observed in many proton accelerators. It will induce transverse beam size blow-up, cause beam loss and restrict the machine performance. Much research work has been done on the causes, dynamics and cures of this instability. A simulation code is developed to study the e-p instability in the ring of the China Spallation Neutron Source (CSNS).  相似文献   

9.
The electron proton (e-p) instability has been observed in many proton accelerators. It will induce transverse beam size blow-up, cause beam loss and restrict the machine performance. Much research work has been done on the causes, dynamics and cures of this instability. A simulation code is developed to study the e-p instability in the ring of the China Spallation Neutron Source (CSNS).  相似文献   

10.
Nonlinear interaction of laser and electron–positron–ion plasmas is investigated by invoking the variational principle and numerical simulation, in terms of a nonlinear Schr o¨dinger equation with inhomogeneities effect. It is shown that the plasma inhomogeneity has great influence on the laser beam dynamics. The laser beam can be self-trapped, focused, or defocused depending on the inhomogeneity character. The linearly decreasing axial plasma density makes the laser beam defocus, while the linearly increasing axial plasma density results in self-trapping of the beam. The self-focusing of the trapped beam is found in a high-density region. For the Gaussian types of density distribution, the beam field submits nonlinearly oscillating regime. The results provide an efficient way to manipulate the dynamics of laser beam propagating in plasma.  相似文献   

11.
HfO2薄膜的结构对抗激光损伤阈值的影响   总被引:19,自引:5,他引:14  
利用蒸发氧化铪和离子辅助蒸发金属铪反应沉积氧化铪薄膜,对两种工艺下制备的氧化铪薄膜进行光学和结构以及激光损伤特性的研究. 实验结果表明,用金属铪反应沉积的氧化铪薄膜不仅结构均匀,并且具有较高的激光损伤阈值. 文章对损伤阈值和薄膜的结构及光学特性之间的关系进行了讨论.  相似文献   

12.
二氧化锆薄膜表面粗糙度的研究   总被引:3,自引:0,他引:3  
采用电子束蒸发工艺,利用泰勒霍普森相关相干表面轮廓粗糙度仪,研究了不同基底粗糙度、不同二氧化锆薄膜厚度以及不同的离子束辅助能量下所沉积的二氧化锆薄膜的表面粗糙度。结果表明:随着基底表面粗糙度的增加,二氧化锆薄膜表面粗糙度呈现出先缓慢增加,当基底的粗糙度大于10nm后呈现快速增加的趋势;随着二氧化锆薄膜厚度的增加,其表面均方根粗糙度(RMS)先减小后增大;随着辅助沉积离子能量的增加,其表面粗糙度呈现出先减小后增加的趋势。  相似文献   

13.
We report electron and Na+ ion emission from single-crystal sodium nitrate (~10 eV band gap) upon exposure to IR (1064 nm, 1.16 eV) laser radiation. The fluence dependence of both the ion and the electron yield is highly nonlinear, and the kinetic energies of the emitted ions can reach values up to 5 eV. The fluence dependence and the ion energy distributions can be understood by a previously presented model involving multiple photon charge transfer plus electrostatic ejection of adions siting atop electron traps. Further evidence for the role of defects in the observed ion emission are provided by two-beam experiments; one beam (UV laser) is used to generate defects and the second beam (IR laser) is used to photodesorb the ions. Such experiments demonstrate that exposure of the sodium nitrate surfaces to UV laser radiation significantly increases the ion emission due to IR laser radiation.  相似文献   

14.
Ten thousands of unit-cell multilayer heterosturctures, [SrNb0.05 Ti0.95O3/La0.9 Sr0.1MnO3]3 (SNTO/LSMO), have been epitaxial grown on SrTiO3 (001) substrates by laser molecular beam epitaxy. The monitor of insitu. reflection high-energy electron diffraction demonstrates that the heterosturctures are layer-by-layer epitaxial growth. Atomic force microscope observation indicates that the surface of the heterosturcture is atomically smooth. The measurements of cross-sectional low magnification and high-resolution transmission electron microscopy as well as the corresponding selected area electron diffraction reveal that the interfaces are of perfect orientation, and the epitaxial crystalline structure shows the orientation relation of SNTO(001)//LSMO(001), and SNTO[100]//LSMO[100].  相似文献   

15.
研究了不同工艺参数条件下,电子束蒸发TiO2薄膜的光学特性。在正交实验的基础上,利用离子束辅助沉积技术,获得了影响TiO2薄膜折射率的主要因素.得到了TiO2薄膜的折射率随氧气分压的关系。对离子氧和分子氧两种情况下TiO2薄膜的折射率进行了比较.得到了TiO2薄膜的折射率与沉积速度的关系,并给出了TiO2薄膜的红外吸收光谱。  相似文献   

16.
Φ0300激光扩束器光学系统设计   总被引:2,自引:1,他引:1  
从三级像差理论出发,分析伽里略(Galilean)和开卜勒(Keplerian)两种类型扩束器的轴外像差没有得到很好校正的原因.通过合理的光路分析,设计出一种轴上和轴外像差都得到很好校正、大口径大相对孔径、视场可增大的、光学性能优于伽里略和开卜勒扩束器的新型扩束器.并给出了物镜通光口径为300 mm、物镜焦距为800 mm、视场为4 mrad、放大倍率为30倍、主工作波长为0.6328 μm的非球面扩束器光学系统结构参量,且进行了像质评价.调整此扩束器目镜组中各镜片的间隔以及物镜和目镜的间隔可以使该扩束器在三个波长使用.  相似文献   

17.
HfO2 films are deposited on BK7 glass substrates by electron beam evaporation. The influences of annealing between 100℃ and 400℃ on residual stresses and structures of HfO2 films are studied. It is found that little differences of spectra, residual stresses and structures are obtained after annealing at lower temperatures. After annealing at higher temperatures, the spectra shift to short wavelength, the residual stress increases with the increasing annealing temperature. At the same time, the crystallite size increases and interplanar distance decreases. The variations of optical spectra and residual stress correspond to the evolutions of structures induced by annealing.  相似文献   

18.
基于二能级模型和多能级模型,分析计算了由强聚焦高斯光束形成的光学偶极阱中87Rb原子5S1/2态和5P3/2态的AC Stark频移。基于多能级模型,针对在852 nm高斯激光束强聚焦所形成的87Rb原子远失谐光学偶极阱中进行偏振梯度冷却的情形,计算了冷却循环跃迁(5S1/2F=2-5P3/2F′=3)的频移量,结果显示频移对molasses冷却过程产生了重要的影响。同时,计算了5S1/2|F=2,mF=±2〉态和5P3/2|F′=3,mF=±3〉态的AC Stark频移随光学偶极阱激光波长的变化情况,发现在红失谐情况下,对于87Rb原子5S1/2-5P3/2态跃迁不存在魔数波长。  相似文献   

19.
CdGd2(WO2)4单晶的顺磁共振谱研究   总被引:1,自引:0,他引:1  
通过粉末XRD测定了CdGd2(WO2)4单晶的晶格常数,由σ- T和ESR实验得出晶体具有顺磁性,但又具有磁各向异性,探讨了晶体的磁各向异性与晶体结构的关系,计算了各向异性g2张量,所得结果和实验符合甚好.   相似文献   

20.
Silicon nanocrystals synthesized by electron beam (e-beam) evaporation of Si and SiO2 mixture are studied. Rutherford backscattering spectrometry of the as-deposited Si-rich silicon dioxide or oxide (SRO) thin film shows that after evaporation, the Si and SiO2 concentration is well kept, indicating that the e-beam evaporation is suitable for evaporating mixtures of Si and SiO2. The SRO thin films are annealed at different temperatures for two hours to synthesize silicon nanoerystals. For the sample annealed at 1050℃, silicon nanoerystals with different sizes and the mean diameter of 4.5 nm are evidently observed by high resolution transmission electron microscopy (HRTEM). Then the Raman scattering and photoluminescence spectra arising from silicon nanocrystals are further confirmed the above results.  相似文献   

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