Modify RF Cavity of 10 MeV Cyclotron to Improve the Beam Gain by Beam Dynamic Analysis

2013 ◽

Vol 405-408 ◽

pp. 1852-1856

Author(s):

Huai Liang Zhu ◽

Xue Wang ◽

Li Feng Yu

Keyword(s):

Dynamic Analysis ◽

Dynamic Responses ◽

Railway Vehicle ◽

Stiffness Coefficient ◽

Key Factors ◽

Constant Acceleration ◽

Euler Beam ◽

Middle Point ◽

Motion Equations ◽

Beam Dynamic

A dynamic model of vehicle-bridge interaction is presented considering the railway vehicle moving through bridge with varying velocity. Assuming the vehicle has a constant acceleration, the motion equations of coupled vehicle-bridge system were deduced based on DAlemberts principle and theory of Euler beam. Dynamic responses of system were analyzed both cases of the acceleration and drag acceleration for a moving car. Results show that the amplitudes of vibration of the system will enlarge sharply with the acceleration of vehicle increasing, and the maximum of responses occur when the vehicle moving at the middle point of bridge. In addition, the stiffness coefficient is one of the key factors to affect on dynamic responses of system. Generally, the suitable rigidity of structure is much important to decrease the responses and suppress the vibration of system.

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Thickness Measurement in the AEM by Macintosh-Based Analysis of Two-Beam Convergent Beam Patterns

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010013612x ◽

1990 ◽

Vol 48 (2) ◽

pp. 504-505

Author(s):

John F. Mansfield ◽

Douglas C. Crawford

Keyword(s):

Electron Microscope ◽

Video Camera ◽

Thickness Measurement ◽

Specimen Thickness ◽

Crystalline Materials ◽

Beam Dynamic ◽

Line Measurement ◽

On Line ◽

Image Position ◽

Convergent Beam

A method has been developed that allows on-line measurement of the thickness of crystalline materials in the analytical electron microscope. Two-beam convergent beam electron diffraction (CBED) patterns are digitized from a JEOL 2000FX electron microscope into an Apple Macintosh II microcomputer via a Gatan #673 CCD Video Camera and an Imaging Systems Technology Video 1000 frame-capture board. It is necessary to know the lattice parameters of the sample since measurements are made of the spacing of the diffraction discs in order to calibrate the pattern. The sample thickness is calculated from measurements of the spacings of the fringes that are seen in the diffraction discs. This technique was pioneered by Kelly et al, who used the two-beam dynamic theory of MacGillavry relate the deviation parameter (Si) of the ith fringe from the exact Bragg condition to the specimen thickness (t) with the equation:Where ξg, is the extinction distance for that reflection and ni is an integer.

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Calculation of many-beam dynamic electron diffraction without high-energy approximation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100163101 ◽

1996 ◽

Vol 54 ◽

pp. 128-129

Author(s):

B. R. Ahn ◽

N. J. Kim

Keyword(s):

Electron Diffraction ◽

Flat Surface ◽

Dynamic Theory ◽

High Energy ◽

Perfect Crystal ◽

Zone Axis ◽

Beam Dynamic ◽

Diffraction Angle ◽

Energy Approximation ◽

The Many

High energy approximation in dynamic theory of electron diffraction involves some intrinsic problems. First, the loss of theoretical strictness makes it difficult to comprehend the phenomena of electron diffraction. Secondly, it is difficult to believe that the approximation is reasonable especially in the following cases: 1) when accelerating voltage is not sufficiently high, 2) when the specimen is thick, 3) when the angle between the surface normal of the specimen and zone axis is large, and 4) when diffracted beam with large diffraction angle is included in the calculation. However, until now the method to calculate the many beam dynamic electron diffraction without the high energy approximation has not been proposed. For this reason, the authors propose a method to eliminate the high energy approximation in the calculation of many beam dynamic electron diffraction. In this method, a perfect crystal with flat surface was assumed. The method was applied to the calculation of [111] zone axis CBED patterns of Si.

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