Design of gridded sheet beam electron gun
A sheet beam gun with spoke grid is designed with EOS [1][2]. The results between with spoke grid and without spoke grid have been compared under the same wiggler magnetic field. When there is spoke grid, the electron beam will have a strong fluctuation in the narrow planar, but will not have great impact in the broad planar.
Recent Developments on EOS 2-D/3-D Electron Gun and Collector Modeling Code
Recent developments on our electron optics simulator (EOS) are reported in this paper. EOS is the finite-element 2-D and 3-D steady-state beam trajectory codes which target problem classes, including axisymmetric guns, gridded guns, multibeam guns, and multistage depressed collectors at present. In order to improve the accuracy, to reduce computational time and computer memory consumption, and to extend the application scope, four significant advances to EOS have been made, and they are presented in this paper. The quadratic interpolation function, which has a higher accuracy than the linear interpolation function, is employed. A time-domain electrostatic model is built to simulate some transient effects. The symmetric computation algorithm and the 2-D model are applied for symmetric and axisymmetric structures to reduce the computational time and the computer memory consumption. Moreover, the results of the modified model and the original model are compared and analyzed in detail.
Modeling Coherent Backscattering Errors in Fiber Optic Gyroscopes for Sources of Arbitrary Line Width
We present a new model of the noise and drift induced by coherent backscattering in a fiber optic gyroscope (FOG) interrogated with a light source of arbitrary temporal coherence. This study is critical to understand whether a FOG driven with a laser instead of a broadband source can attain high sensitivity and stability, which would have the overwhelming benefit of improving the FOG scale factor stability by at least ten-fold and would enable the use of FOGs for inertial navigation of aircrafts. Analytical and numerical solutions bring to light two significant new predictions. First, coherent-backscattering noise can be made negligibly small by utilizing a laser with a very narrow linewidth (less than ~ 20 kHz), although in this regime the drift is high. Second, by using a laser with a broad linewidth (greater than ~ 10 MHz), both the noise and the drift are low enough for aircraft inertial navigation. The dependencies of the noise and drift on fiber loss, loop coupling coefficient, and backscattering coefficient are also presented to define the optimum mode of operation of this new class of FOGs.