摘要:

AbstractBecause of the varieties and the potentialities in technological and scientific applications of E x B type discharges, a systematic theory to interpret phenomena occurring there must be developed. This paper proposes to develop a theory of a small fluctuating electric field by which the electric field of the crossed field system is superposed. The resonance between the fluctuation and the motion of ions confined in the field system induces a convergence to a component of the ionic motion. As a result, under a certain condition, the chaotic ions in the field system form spokes. These phenomena (spoke formation process and spoke rotation) observed in E x B devices are interpreted by comparing the theoretical results.

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710201

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractIraditionally, Ar gas has been used forring. However, when a hydrogenized amourphous film is formed by reactive sputtering the disturbance of the bonding network in Si by the incorporated Ar atoms and the collision of the highly energized Ar particles to the Si substrate cause a high density defects in the film.The compressed magnetic field magnetron sputerring system has been developed to minimize the damage to the substrate and to enable film deposition at low temperature. High‐quality a‐Si:H film has been formed by using He whose atomic radius is smaller than of Ar. In this paper, the characteris of the compressed magnetic field‐magneting sputtering system are described. The film is characterized by using the pressure of hydrogen as a parameter. over, the characteristics and thermoprotion of the film by He sputtering are computer with those of the film by Ar sputter.As a result: (1) in case where He was the film characteristics depended higly on the partial pressure of H2when low (<1.0 mtorr). The best film was when the partial pressure of hydroling was 0.5 mtorr; and (2) the film by He harring did not show degradation by the treatment at temperatures up to

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractRecently, surface acoustic wave devices have been used in many fields, for example as filters and so forth. However, since the device characteristics are determined by the substrate, the superior substrate for surface acoustic wave applications has been investigated. In this study, the leaky surface acoustic wave propagating in LiNbO3has been evaluated theoretically and experimentally. First, the contour maps of the characteristics have been obtained for an arbitrary cut, and the propagation characteristics of the leaky surface acoustic wave in the LiNbO3have been investigated. As a result, the standard for the substrate selection has been established. It was proven theoretically and experimentally that the proper selection of the cut could provide both the high electrical‐mechanical coupling coefficient (15%) and such excellent thermal characteristics as zero temperature coefficient which could not be obtained by conventional devices using Rayleigh wave propagation. As a result, a large electrical‐mechanical coupling (13.1%) which agreed with the theoretical value, has been obtained and the thermal characteristic (50 ppm/°C), much superior to that of conventional devices, has been obta

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractA systematic theory to interpret discharge phenomena generated in E x B structural discharge devices (magnetron type, PIG type, concentric quasi‐spherical type, and so forth) is developed by applying the classical magnetron theory to E x B structural systems. The transforming efficiencyh, γ) from the electrostatic energy of a charged particle (massm) in an electrode system (voltage between the electrodesVCA) to the discharge energy and the coefficient ε(η,r)/(JQVCA/r2) of the energy ε per unit time in unit volume of the discharge bulk are obtained where a device constantk = e(r2B)2gives the dimensionless quantityh= √m/k; γ(<1) is a ratio of the electrodes' radii,JQis the current density at the inner electrode γr2,r2is the outer‐electrode radius, the potentialU2isU2=VCA/(1 ‐r2), andBis the magnetic flux density.The discharge occurs under the conditionh2+r2<1. Because 1 ‐ η is consumed for heating electrodes (raising the temperature of a device), one may select the optimum condition ofhand γ for η → 1 if possible. The coefficient of ε is advantageous for γ +1, but care must be taken because it has a maximum value with the parameterh. The energy ε is related to the density and the temperature of discharge products, and the purposes of the device use.As for experimental examples of the forementioned types of devices, considerations and comparisons with calculated results ofh, γ η and ε are given.The theory presented in this paper is useful for designing such devices as ion sources for ion beam technology, and fundamental researches on cosmic plasmas and nuclear fusion plasmas and for interpreting discharge phenomena generated

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractBased on linear small‐signalSparameters, large‐signalSparameters are described in terms of the output of the amplifier. With the use of theseSparameters, the maximum available power gain under the large‐signal operation is discussed. The basic analysis method is based on the power chart representation of the input and output powers proposed by Linvill. The input and output powers are represented as points on two paraboloids. From the graphical relation of this parabola, the unconditional stability condition and the input and output matching condition can be formulated. The gain compression phenomena under the large‐signal operation is investigated. Next, with microwave GaAs MESFET's, the measured results of the large‐signalSparameters are shown, as well as the experimental results of the maximum available power gain by the effective load‐pull method. It is shown thatS21andS22of theSparameters have output power dependences of the quadratic form. It is also found that the theoretical maximum available power gain computed from the linear small‐signalSparameters and the nonlinear coefficient of the output power dependence agrees well with the experimental values measured by the effective loa

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractIn the optical heterodyne communication and measurement based on semiconductor lasers, selection of an arbitrary frequency within a broad gain spectral width and continuous and broadband FM operation are needed. This paper reports a theoretical study on a laser diode (LD) with a composite optical cavity using an external reflector. Using a GaAlAs LD with an adjacent plane or spherical mirror, a broadband tuning of oscillation frequency of about 8 THz (18 nm) becomes possible by variation of the external cavity length. Further, by modulation of the injection current, a continuous FM shift as large as 150 to 290 GHz is realizable which is three to five times the conventional value.

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractA new NMR imaging technique is described. A selective excitation is given in a line‐shaped focusing field. The spin distribution in the one‐dimension line‐shaped excitation region is detected with a linear magnetic field gradient. The methods of generating the line‐shaped magnetic focusing field and its scanning are described together with the selective excitation characteristic. Experiments of imaging with an 819‐kHz pulsed NMR system and their results are shown. The data collection time of the method was examined, showing much shorter time than conventional line‐scanning methods. This is because the spin excitation is carried out only for a necessary region. When a single slice is required, the imaging time can be about the same period as in a conventi

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractA method of solution based on a linear prediction method is presented for an inverse scattering problem in which the permittivity ε(x) and the conductivity s̀(x) in a one‐dimensional inhomogeneous lossy material are estimated from the reflected and transmitted waves. The present method is shown in the following manner. First, from Maxwell's equation governing the medium, coupled equations for the forward and backward waves are derived which subsequently are discretized. In the discretized coupled equations, the permittivity ε(x) and the conductivity s̀(x) are included as coupling potentials. Also, if these discretized coupled equations are used, the transmitted and reflected waves for the incident impulse are an AR and an ARMA process, respectively. Their AR and MA parameters are closely related to the coupling potentials. Hence, from the reflected and transmitted waves for the incident impulse, the permittivity and permeability of the medium can be determined via the coupling potentials. To confirm the validity of the forementioned method, several computer simulations have been carrie

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractThe integral equation method for electromagnetic‐wave scattering problems has difficulty in that we can not obtain a unique solution when the wave numbers of electromagnetic waves agree with the eigenwave numbers of the system under consideration. In this paper, we derive an integral equation satisfied at arbitrary observation points inside a scattering body and propose a method to place all finite numbers of the observation points (this number agrees with the number of the expansion coefficients for approximating the unknown field function) on an appropriately arbitrary closed curve located inside the scattering body. Through the newly proposed method described in this paper, we can easily avoid an inherent difficulty of an integral equation, compared with the existing methods, specifically, by adding internal conditions and by using integral equations of mixed types. As a numerical example, we solved a case of a plane wave incidence on a perfectly conducting elliptic cylinder. Using the boundary elements method, we carried out numerical calculation and showed that the solution of a high degree of precision can be obtained easil

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY

摘要:

AbstractTo increase the sensitivity of distributed gas or liquid sensors using the evanescent wave of optical fibers, methods such as making the fiber single‐mode and reducing its cladding thickness or removing it completely, can be considered. However, the core of the single‐mode fiber is only a few micrometers in diameter and, therefore, it becomes very difficult to preserve it without the cladding layer. On the other hand, increasing the cladding thickness will reduce its sensitivity. In this paper, the eccentrically cladded fiber is proposed as a means to increase the sensitivity without the need to reduce its diameter. The theoretical analysis and its experimental verification are carried out. As a result, it is shown that if the eccentricity is increased, the sensitivity will not decrease remarkably, even at large cladding diameters. Further, as experimental evidence of liquid detection, optical losses of a few decibels per centimeter were observed by attaching a liquid to the fiber. This indicated the possibility of highly sensitive distributed‐type sensors. Because of the good agreement of theoretically estimated radiation losses of W‐type fibers with experimental results, it is concluded that eccentrically cladded fibers can be designed to exhibit the desired sensing characte

ISSN:8756-663X    

DOI:10.1002/ecjb.4420710210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1988

数据来源: WILEY