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1987 Vol. 9, No. 3
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1987, 9(3): 193-204.
Abstract:
There are two different expressions for anode current of pulsed magnetrons. The one. comprising electric and magnetic parameters as well as tube geometries, describes how the electrons are picked up from the rotating electron stream near anode space; the other, stating the relation between thermal emission, coefficient of back bombardment and coefficient of secondary emission, is a general description of supplying electrons to the rotating stream by the ca-thode without concern to a particular tube. Each of the above expressions has its own physical significance while they are closely connected to each other through the rotaing eectron stream. The integration of these expressions with the electron motions in the interaction space leads to better understanding of the mechanism of magnetrons. For stable operation of the magnetron, the preoscillation voltage should be lower than the threshold voltage, while the mode of this space charge oscillation should be the same as the mode oscillation on the resonating cavities. After starting of the resonance, that the thermal emission approximately equals the back bombarding current and the secondary emission approximately equals the anode current respectively exhibits condition of good performance.
There are two different expressions for anode current of pulsed magnetrons. The one. comprising electric and magnetic parameters as well as tube geometries, describes how the electrons are picked up from the rotating electron stream near anode space; the other, stating the relation between thermal emission, coefficient of back bombardment and coefficient of secondary emission, is a general description of supplying electrons to the rotating stream by the ca-thode without concern to a particular tube. Each of the above expressions has its own physical significance while they are closely connected to each other through the rotaing eectron stream. The integration of these expressions with the electron motions in the interaction space leads to better understanding of the mechanism of magnetrons. For stable operation of the magnetron, the preoscillation voltage should be lower than the threshold voltage, while the mode of this space charge oscillation should be the same as the mode oscillation on the resonating cavities. After starting of the resonance, that the thermal emission approximately equals the back bombarding current and the secondary emission approximately equals the anode current respectively exhibits condition of good performance.
1987, 9(3): 205-212.
Abstract:
Properties of coherent radiation of millimeter wave generated by a intense rotating annular relativistic electron beam (E-layer) which is from a cusp magnetic field are investigated. The linearized Vlasov-Maxwell equations are used to analyze the interaction between E-layer and re-sonnator of magnetron. The dispersion relation is deduced and numerical calculation is made. The results show that the frequency of microwave radiation is r(r = l∥ where ∥ is the electron relativistic cyclotron frequency in the axial magnetic field; l is the aximuthal mode number, l=n+mN; N is the number of side resonnators, n=0, 1, 2, N/2, m is any integer). The growth rate of radiation is still large enough even if l is good for generating millimeter wave radiation at low axial magnetic field. If the modes can be controlled well, a tunable, high power millimeter wave device can be made.
Properties of coherent radiation of millimeter wave generated by a intense rotating annular relativistic electron beam (E-layer) which is from a cusp magnetic field are investigated. The linearized Vlasov-Maxwell equations are used to analyze the interaction between E-layer and re-sonnator of magnetron. The dispersion relation is deduced and numerical calculation is made. The results show that the frequency of microwave radiation is r(r = l∥ where ∥ is the electron relativistic cyclotron frequency in the axial magnetic field; l is the aximuthal mode number, l=n+mN; N is the number of side resonnators, n=0, 1, 2, N/2, m is any integer). The growth rate of radiation is still large enough even if l is good for generating millimeter wave radiation at low axial magnetic field. If the modes can be controlled well, a tunable, high power millimeter wave device can be made.
1987, 9(3): 213-220.
Abstract:
In this paper, the computations of large signal interaction in Orotron with several models of field are carried out. Models of field include uniform and Guassian distribution field; the mode including only one foundamental forward wave and modes including the backward wave and harmonics are both considered. After analysing all the results of the computation for a series of the parameters, the useful results for further investigation of the characteristics of Orotron and for designning the Orotron rae got.
In this paper, the computations of large signal interaction in Orotron with several models of field are carried out. Models of field include uniform and Guassian distribution field; the mode including only one foundamental forward wave and modes including the backward wave and harmonics are both considered. After analysing all the results of the computation for a series of the parameters, the useful results for further investigation of the characteristics of Orotron and for designning the Orotron rae got.
1987, 9(3): 221-228.
Abstract:
This is the second one of two papers about designing the saddle deflection yoke with 3 ferromagnetic shield. By using the expressions of the field parameters given by the author et al (1987) and with the aid of orthogonal design method, we optimized the design of the saddle deflection yoke with a ferromagnetic shield. The results obtained agree with the practical model. It is pointed out that the end-ear and the distribution of the field parameter B0(z) have important effects on the deflection aberrations. An example is given that compares the electron optical properties of the deflection coils with cosine-distribution and finite length with that of the deflection coils with distributed winding.
This is the second one of two papers about designing the saddle deflection yoke with 3 ferromagnetic shield. By using the expressions of the field parameters given by the author et al (1987) and with the aid of orthogonal design method, we optimized the design of the saddle deflection yoke with a ferromagnetic shield. The results obtained agree with the practical model. It is pointed out that the end-ear and the distribution of the field parameter B0(z) have important effects on the deflection aberrations. An example is given that compares the electron optical properties of the deflection coils with cosine-distribution and finite length with that of the deflection coils with distributed winding.
1987, 9(3): 229-234.
Abstract:
Merging the widdle factors in two neighbouring stages for frequency-decimal FFT algorithm, we can obtain the twiddle factor merged frequency-decimal FFT algorithm. Its result is exactly the same as that of the rescursive cyclotomic factorization algorithm (RCFA) which Martens (1984) proposed by using polynomial algebra theory. So it has the advantages of simple structure and high efficiency. It is much easier to be understood and used by engineers than RCFA, and it is also easy to be generalized for the time-decimal case.
Merging the widdle factors in two neighbouring stages for frequency-decimal FFT algorithm, we can obtain the twiddle factor merged frequency-decimal FFT algorithm. Its result is exactly the same as that of the rescursive cyclotomic factorization algorithm (RCFA) which Martens (1984) proposed by using polynomial algebra theory. So it has the advantages of simple structure and high efficiency. It is much easier to be understood and used by engineers than RCFA, and it is also easy to be generalized for the time-decimal case.
1987, 9(3): 235-243.
Abstract:
This paper presents a unified theory of augmented graph. Two basic theorems for a matrix are proved. By making use of graph augmentation, evaluation of the determinant and cofactors associated with a matrix is carried out in one single analysis which is referred to the J-operation, so that is of a set of linear algebraic equations. The augmented Coates graph and Mason graph are topologically simplified. Since the need for the formulas called D-operation is eliminated, the augmented graph serves as a theoretic basis, on which the existing network topology could be reduced greatly.
This paper presents a unified theory of augmented graph. Two basic theorems for a matrix are proved. By making use of graph augmentation, evaluation of the determinant and cofactors associated with a matrix is carried out in one single analysis which is referred to the J-operation, so that is of a set of linear algebraic equations. The augmented Coates graph and Mason graph are topologically simplified. Since the need for the formulas called D-operation is eliminated, the augmented graph serves as a theoretic basis, on which the existing network topology could be reduced greatly.
1987, 9(3): 244-255.
Abstract:
The directed hypergraph theory is presented, and by applying it the directed k-hypertree method for hypernetwork analysis is derived. Using this method the scale of electrical networks which can be topologically analysed by a computer will be increased, and the resultant expressions are compact.
The directed hypergraph theory is presented, and by applying it the directed k-hypertree method for hypernetwork analysis is derived. Using this method the scale of electrical networks which can be topologically analysed by a computer will be increased, and the resultant expressions are compact.
1987, 9(3): 256-263.
Abstract:
The energy positions and carrier capture cross-sections of the deep levels related to copper in silicon are measured by DLTS. The annealing behaviour and spatial distributions of some of these levels are studied at the same time. The results show that there are not any triple acceptor or quadruple state corresponding to substimtional copper in silicon, which have been reported in the literature. Most of the deep levels related to copper in silicon are corresponding to complexes of copper and defects in silicon.
The energy positions and carrier capture cross-sections of the deep levels related to copper in silicon are measured by DLTS. The annealing behaviour and spatial distributions of some of these levels are studied at the same time. The results show that there are not any triple acceptor or quadruple state corresponding to substimtional copper in silicon, which have been reported in the literature. Most of the deep levels related to copper in silicon are corresponding to complexes of copper and defects in silicon.
1987, 9(3): 264-268.
Abstract:
In this report the diffusion of Zn into Ge is investigated. The experiments are accomplished in an evacuated and sealed quartz ampoule using Zn as the diffusion source. The xj-t1/2 and C-1/T has been given. The influence of the source temperature on rhe curface micro-graph has been given. It is found that using two-temperature process a smooth surface layer can be obtained.
In this report the diffusion of Zn into Ge is investigated. The experiments are accomplished in an evacuated and sealed quartz ampoule using Zn as the diffusion source. The xj-t1/2 and C-1/T has been given. The influence of the source temperature on rhe curface micro-graph has been given. It is found that using two-temperature process a smooth surface layer can be obtained.
1987, 9(3): 269-272.
Abstract:
The nonparametric constant false alarm rate (CFAR) property of digital polarity sampled phase reversal coded pulse compressors is described. The detection performance in Gaussian and non-Gaussian noise is determined. It is shown that the loss in signal-to-noise ratio of the processor, relative to the incoherent matched filter, decreases as the code length increases, the asymptotic loss in Gaussian noise is 1.96 dB, and the loss in Weibull noise decreases with the shape parameter of the Weibull distribution and can even become a gain.
The nonparametric constant false alarm rate (CFAR) property of digital polarity sampled phase reversal coded pulse compressors is described. The detection performance in Gaussian and non-Gaussian noise is determined. It is shown that the loss in signal-to-noise ratio of the processor, relative to the incoherent matched filter, decreases as the code length increases, the asymptotic loss in Gaussian noise is 1.96 dB, and the loss in Weibull noise decreases with the shape parameter of the Weibull distribution and can even become a gain.
1987, 9(3): 273-277.
Abstract:
The basic principle and method of measuring the antenna excess noise temperature Tas by using the radio stars as calibration are presented in this paper. In this method, the antenna noise temperature TAN is used as a standard of calibration when the antenna points at sky. It was found that the results of measurement using this method agree with that obtained by using liquid nitrogen at low and normal ambient temperature as standard of calibration. The method has advantage of more simplicity of the measurement and equipment. The total error of antenna excess noise temperature obtained by this method could be estimated to be 3%. The error of antenna gain measured is about 0.3%.
The basic principle and method of measuring the antenna excess noise temperature Tas by using the radio stars as calibration are presented in this paper. In this method, the antenna noise temperature TAN is used as a standard of calibration when the antenna points at sky. It was found that the results of measurement using this method agree with that obtained by using liquid nitrogen at low and normal ambient temperature as standard of calibration. The method has advantage of more simplicity of the measurement and equipment. The total error of antenna excess noise temperature obtained by this method could be estimated to be 3%. The error of antenna gain measured is about 0.3%.
1987, 9(3): 278-282.
Abstract:
A theoretical analysis is given in this paper to the structure of a cross-coupled coaxial-waveguide diode mount--a major module of power combiner. The equivalent circuit isobtained. It is shown by computer simulation that the shorted out position l4 of a cavity can be determined and the power ratio is related to the mismatched load z1, to the output impedance z3 of cavity and their position l1 and l3, to the radius r of inner conductor of a coaxial line and to the distance between coaxial lines. According to these results, a optimum design of millimeter wave combiner is discussed proved by expriments.
A theoretical analysis is given in this paper to the structure of a cross-coupled coaxial-waveguide diode mount--a major module of power combiner. The equivalent circuit isobtained. It is shown by computer simulation that the shorted out position l4 of a cavity can be determined and the power ratio is related to the mismatched load z1, to the output impedance z3 of cavity and their position l1 and l3, to the radius r of inner conductor of a coaxial line and to the distance between coaxial lines. According to these results, a optimum design of millimeter wave combiner is discussed proved by expriments.
1987, 9(3): 283-288.
Abstract:
The process of the energy exchange between the E-beam and wave in a cetrifugal electrostatic focusing system is analyzed theoretically in this paper. A kinetic description and discussion related to the project are given. A new method to inject the E-beam obliquely is proposed.
The process of the energy exchange between the E-beam and wave in a cetrifugal electrostatic focusing system is analyzed theoretically in this paper. A kinetic description and discussion related to the project are given. A new method to inject the E-beam obliquely is proposed.
