Yin Hanchun

Simulation study on performance of field emitter array

An improved finite difference method is used to study the field emitter arrays in both diode and triode modes. In the simulation, the boundary of the emitter can be fitted with irregular meshes. The emission performance of the emitter array is analyzed in this article. Simulation results show that the electric field at tips in the emitter array is not uniform. The emission currents from tips are also different. Due to the influence of the interaction and fringe field, the emission currents from tips near the edge of the array are larger than that from tips on the center part of the array. However, the presence of the gate can reduce the interaction between neighboring tips in the triode structure. Thus, it is possible to achieve a higher current density in the triode mode.

Study of the emission performance of carbon nanotubes

The carbon nanotube has good field emission properties, so it has been used as the electron source on the field emission display panel. To obtain a high emission current, the electric field at the tip of the nanotube must be large enough. This article studies the variation of electric field with different types of nanotubes. The emission current of the nanotube is also calculated for various geometrical parameters of nanotubes. From the simulation results, the influence of the geometrical parameters on the emission performance of nanotubes is studied.

Influence of the fringe field and the field interaction on the emission performance of a diode emitter array

Abstract In the field emitter array, there is a fringe field surrounding the emitter array. The fringe field and the interactive field between different tips will influence the emission uniformity of the emitter array. This paper studies the influences of the fringe field and the interactive field on the emission performance of a diode emitter array. The variations of the emission currents versus the width of the margin of the array are given. From these results, the influences of the fringe field on the emissions of the center tips and the corner tips are obtained. This paper also analyses the dependence of the fringe field and the interactive field on the cathode–anode distance and the tip-to-tip spacing.

Optimization of a particle optical system in a mutilprocessor environment

In the design of a charged particle optical system, many geometrical and electric parameters have to be optimized to improve the performance characteristics. In every optimization cycle, the electromagnetic field and particle trajectories have to be calculated. Therefore, the optimization of a charged particle optical system is limited by the computer resources seriously. Apart from this, numerical errors of calculation may also influence the convergence of merit function. This article studies how to improve the optimization of charged particle optical systems. A new method is used to determine the gradient matrix. With this method, the accuracy of the Jacobian matrix can be improved. In this paper, the charged particle optical system is optimized with a Message Passing Interface (MPI). The electromagnetic field, particle trajectories and gradients of optimization variables are calculated on networks of workstations. Therefore, the speed of optimization has been increased largely. It is possible to design a complicated charged particle optical system with optimum quality on a MPI environment. Finally, an electron gun for a cathode ray tube has been optimized on a MPI environment to verify the method proposed in this paper.

Analysis of the emission performance of field emitter with Laplace interpolation method

It is well-known that the electric field changes largely around the tip of the field emitter. Since the emission current density is very sensitive to the electric field, it is important to analyse the distribution of electric field and emission current density across the emitter tip accurately. Usually, the interpolation method is used to estimate the electric field at arbitrary point around the tip. However, some errors may be introduced in the interpolation of the electric field. These errors cause a large deviation in the calculation of current density. In order to analyse the emission performance of the field emitter precisely, this paper proposes a new interpolation method to estimate the electric field at any point. In this method, the basis functions satisfy the Laplace equation automatically. Therefore, it can be used to calculate the electric field and emission current density of the field emitter accurately. A spherical capacity and a diode emitter are analysed with the Laplace interpolation and Lagrange interpolation, respectively. As shown in the results, the electric field and emission current density calculated with Laplace interpolation are more accurate than the one calculated with Lagrange interpolation.

Simulation of field emitter array in diode model

Abstract In the application of field emitter arrays, it is useful to understand its emission performance. This paper calculates the electric field of a diode emitter array in three-dimensional space. From this calculation, the emission uniformity of a diode array is studied. The dependance of the tip-to-tip spacing and of the cathode–anode distance on the uniformity of the array is also analyzed. The pressure sensor based on the diode model is simulated. From the dependence of the emission current for different tip densities, the influence of the emission uniformity can be obtained.

Sensitivity analysis of the field emitter

Many types of field emitters have been studied up to now to improve the emission current. However, only the ideal parameters are taken into account in some designs. In the fabrication process, the structural parameters of emitters may change. Therefore, it is useful to analyze the parameter sensitivity of the field emitter. This sensitivity should also be included in the defect function of the optimum design. In this article we propose a method to calculate the derivative of the electric field and emission current density versus geometrical parameters of emitter. This derivative can be used to represent the parameter sensitivity of the field emitter. Using this method, the sensitivities of some parameters in the diode and triode emitters are analyzed.

Carbon-Nanotube-Based Normally-on-Driving Under-Gate Field Emission Display Panel

A carbon-nanotube-based normally-on-driving under-gate field emission display (FED) panel and its operation principle are presented. In this panel, field emission electrons are extracted directly from the cathode by the high anode voltage. The image is realized by modulating the voltage of under-gate, whose value is less than the cathode voltage, to stop the cathode producing field emission electrons. The electric field inside the emission region is calculated by the finite element method. The emission property of the cathode is also studied by numerical calculation method. The results indicate that a uniform and large emission area can be obtained in this new under-gate FED panel. This study provides powerful theoretic support for the feasibility of this new kind of under-gate FED panel.

Perturbation of trajectory caused by small displacement of electrode

Abstract In the design of devices containing beams of charged particles, it is helpful to know how the particle’s trajectories will be modified by small displacement of electrodes. This paper describes a method to predict the perturbation of particle trajectories. In this methodology, the derivative of the potential is deduced from the results of finite element computation. The equation of motion is solved to calculate the perturbation of particle trajectories separately. An example of a perturbation trajectory in an electrostatic lens is presented.

Characteristic and Circuit Model of a CNT-FED Subpixel

A basic triode structure of carbon nanotube field emission display was shown which has three electrode, anode, gate and cathode electrodes. A circuit model for the subpixel of the panel, the capacitance and resistance in the CNT-FED panel is evaluated. From the simulation using pspice, the decrease in the value of the capacitance, would reduce the rising and falling time of the driving voltage