A linear and nonlinear analysis of a crossed field gyrotron operating on theTEm11 whispering gallery mode are presented. The detailed discussions are given for the starting oscillation condition, the effect of the internal conductor in coaxial cavity on the cut-off frequency of mode and spacing between adjacent modes as well as the effects of the applied voltage on the cyclotron frequency of electron, the starting oscillation beam power and electron efficiency. It is shown that the efficiency of 41% may be obtained for m=2. A comparison of these results with those in cylindrical cavity is made. The analysis is helpful for the engineering design.

Secmotron (Sector beam deflection modulated tube) is a new kind of high efficient microwave tube which is developed on the basis of gyrocon. Its pervance is higher than that in gyrocon. Therefore, the,secmotron can be operated at rather lower voltage. Consequently, a double ridge ring cavity is used as its output one. The ring cavity is analyzed with approximative methods. The design of the cavity and optimization of its dimensions are also given. The measured results of a test model is coincident with the calculated ones fairly.

Starting from the basic integral equation for multiple scattered fields, a set of coupled linear equations for the expansion coefficients of elastic multiple scattered fields by randomly distributed spherical scatterers has been derived by using the expansions of the fields and the translational addition theorems of the vector spherical wave functions. Thus a new theory for this kind of problems is developed. This theory is different from the others in the multiple elastically scattered fields in all space regions.

Theory and numerical computation of EM field distribution rule in a biological medium with irregular shape are described. Integral equations on induced EM field distribution in biological body are deduced from EM field scattering. Numerical computations are conducted by the moment method. In order to verify effectiveness of the theory, a set of experimental equipment i? designed precisely. The results of numerical computation are compared with measured values. It is shown that they are agree very well. This theory can be used widely for its generality.

Firstly, the Foutier transforms in finite fields and the concept of linear complexity of squences are described. Then several lower bounds on the minimum distance of cyclic codes are outlined. Finally, the minimum distance of cyclic codes is analyzed via linear complexity of squences, and new theorems about the lower bounds are obtained.

In general speaking, the quantitative analysis of D_φ^(N)(τ) behavior was very complex. Based on the stochastic signal processing theory, a effective analysis is proposed. Then, a new D_φ^(N)(τ) definition which is called the modified D_φ^(N)(τ)is given. Applications of D_φ^(N)(τ) in the linear estimation is described.

Four new single amplifier switched-capacitor (SC) bandpass filters with the partial positive feedback are presented through introducing the positive feedback into a single amplifier configuration with negative feedback. Design equations and their optimal solutions to minimize the capacitor spered for these circuits with given pole frequency ω₀ and Q₀ values are obtained. Compared with the circuits given by literature, the capacitor spreads for proposed circuits are significantly reduced.

The state space tree method for finding communication network overall reliability is presented. It directly generates one disjoint tree multilevel polynomial of a network graph. Its advantages are small computational effort and short resulting expression. Based on the state space tree method, an exact decomposition algorithm for finding communication network overall reliability is presented by applying the hypergraph theory. If the m-time decomposition of a network graph is carried out by the algorithm, then the communication network scale which can be analyzed by a computer can be extended to m-fold.

半导体物理; 半导体器件; 模拟; 数值分析

The emission characteristics of liquid metal ion source are simulated by Monte Carlo method. The initial positions and velocities of emitted ions are given by random sampling with random numbers. Trajectory calculations including the effect of discrete space charge are carried out with fourth order auto-variable-step Runge-Kutta method. In order to accelerate the convergence of Poisson field, the total emission current is kept constant in the iterative process, and we assume the quantity of voltage variation between two succesive iterations as the iterion of convergence. Finally, the emission characteristics of the ion source such as angular current intensity, energy spread, beam divergence, virtual source size and its position are given.

A fault testability of analog circuits is discussed. The numerical judgment method for fault testability based on the numerical rank of matrices is presented. The testability conditions which not only include the topological testability restriction, but also takes the parameter tolerances and numerical errors into consideration, are given. According to the different requirments in testability analysis and designs, the testability condition is separated into two parts: topological condition and numerical restriction. The criterion of the later is presented here, while the former was given in Ref.[1].

Two methods are given in order to generate a class of sequences controlled by a clock and a knapsack function. It is shown that, under some simple assumptions, this class of sequences has minimum polynomial h(x^q), complexity nq and period (2ⁿ-1)q, where h(x) is a primitive polynomial of order n over GF(2) and q is the period of a binary sequence.

It has been demonstrated that a TEM field can be supported in a rectangular waveguide loaded with two dielectric slabs of different dielectric constants and thicknesses. The relations of slab thickness with respect to both the relative constant and operating frequency in the waveguide to support the TEM field are given. And the transmission characteristics of this kind of waveguide are discussed.

This paper presents the perfect match formula and perfect isolation formula for the parallel lines directional couplers in general case, and gives the necessary and sufficient condition by which match and isolation can be realized simu ltaneously.

An automatic testing and plotting system of Rieke diagram is described. In this system, microcomputers are utilized to control the variable mismatch microwave load, to sample the tested data, to process these data and to plot the diagram. Several Rieke diagrams of microwave tube worked at X band are plotted.

The incorporation and behavior of impurity Zn in VPE of GaAs are studied by using metallic Zn as a dopant in Ga-AsCl₃-H₂ system.The distribution coefficient and hole concentration of Zn in GaAs are 10 and >1×10²⁰cm^-3 respectively, which are 3 or 2 order greater than that of Cd doping, and it ensures the preparation of p-GaAs with high hole concentration for photocathode fabrication. Combining Zn and S doping techniques, the p-n junction structure materials were reproducibly produced with more abrupt transition interface.

The effect of the γ-ray irradiation on the characteristics of 1.3 μm InGaAsP/InP DH LED used in the optical fiber conmmunication is investigated. When the irradiation dosage is in the rang of 1× 10⁵-1×10⁷ rad, the output power and the Cut-off frequency of the devices do not change. When the irradiation dosage is higher than 1×10⁷ rad, the output power dec-Teases and the cut-off frequency increases, owing to the minority carrier lifetime decreases. The EL pattern does not change during the y-ray irradiation.