Impedance Matching Method Research Articles

Control of multipolar electron cyclotron resonance discharges using internal cavity impedance matchinga)

Recently, electron cyclotron resonance (ECR) discharges have been successfully applied to numerous ion source applications. These range from accelerator to etching and thin film deposition applications, and have strong potential for application in several commercial/industrial processes. Thus, new design requirements related to process automation and control are now imposed on plasma source design. Internal cavity tuning methods for excitation and impedance matching and ECR discharge control are presented. These impedance matching methods utilize a variable cavity end plate and an adjustable coupling probe to provide the two independent adjustments required to match the discharge loaded cavity applicator. Both end feed and side feed coupling create a well matched plasma source but the end feed excitation produces the most efficient (∼220–230 eV/ion) and most uniform (1σ=2.5%) discharge. Control of internal tuning can serve not only to match discharge impedance, but with the proper control can also avoid hysteresis and multiple steady states and jumps in plasma source outputs. Adjusting the internal cavity tuning to always produce a slight mismatch helps insure a stable and repeatable discharge operation.

純鉄粉の爆発圧縮成形

Explosive compactions of pure electrolytic iron powder have been conducted using a cylindrically axisymmetric direct method. In the explosive compaction, the ratio of explosive mass to powder mass (E⁄M ratio) and the detonation velocity of explosives were changed to investigate their effects on the compactibility. The optimum compacts, where no cracks were included, were obtained at the E⁄M ratio between 2.5 and 3.0 using PAVEX (detonation velocity 2.3 km/s), and the specific density ratio of the optimum compact reached more than 99%. The compacting pressure estimated using the impedance matching method was about 4.5 GPa for the optimum compaction. On the contrary, no optimum compacts were obtained using SEP (detonation velocity 6.97 km/s), because the compacting pressure was changed drastically with the E⁄M ratio from under-compaction to over-compaction. This result indicates that the use of slow detonation velocity explosive was more favorable to obtain a crack-free compact. Although the tensile strength of the as-compacted material was about 40 MPa, it was increased to 300 MPa by post-sintering treatment at 1123 K for 900 s. The mechanical properties of the explosively compacted and sintered material were superior than those of the conventionally sintered material and were comparable to the melted material.

Selection of DC motors and reduction gears for robots with consideration of energy consumption.

The data bases of DC Servo motors and reduction gears on the market are constructed. Based on them, the minimum capacity method is proposed as an exellent selection method of motors and reduction gears, which makes the capacities of motors minimum for given mechanisms and works. Motors and reduction gears are selected for some robot mechanisms and prescribed works by the minimum capacity method and by the impedance matching method respectively, and the amounts of energy consumption by the motors selected by the two methods are calculated and compared with each other. Contributions of the self-locking function and efficiency of reduction gears to the energy consumption are also discussed.

Synthesis of impedance transformable filter by artificial nonuniform transmission line with distortionless property

AbstractThis paper proposes a simple synthesis method of impedance matching and transforming filter. This method is based on the use of a multistage ladder network simulating a nonuniform transmission line. When the filter charactersitic functions defined in this paper satisfy the distortionless conditions of the voltage and current waveforms the artificial transmission line mentioned above almost operates as an ideal lowpass filter. As an example the characteristics of 1 ‐ 2ω transformable type lowpass filter are evaluated and the obtained results almost satisfy the conditions for the ideal filter.

Propagator matrix method for calculation of normal modes in a stratified ocean overlying inhomogeneous anisotropic porous beds

A practical algorithm for the calculation of acoustic normal modes at excitation frequencies of 50 to 5000 Hz in a shallow stratified ocean overlying a transverse isotropic poroelastic sediment bed is developed. The Biot‐Willis stiffness matrix which describes poroelastic anisotropy in terms of physical properties of sediments is used to model the bed. The propagator matrix method is used to solve the differential equations for the motion stress vectors in both layered sediment and water. The method of impedance matching is used to obtain the eigenvalues of the system numerically. Using measured in‐situ properties of sediment (presented separately in this meeting), the effect of sediment anisotropy and inhomogeniety on acoustic wave propagation is studied for shallow water propagation at the Great Bahama Bank. [The work was sponsored by ONR Codes 425UA.]

Coupled Rotor/Airframe Vibration Analysis by a Combined Harmonic-Balance, Impedance-Matching Method

Coupled Rotor/Airframe Vibration Analysis by a Combined Harmonic-Balance, Impedance-Matching Method

Analysis of the wide band gyrotron amplifier in a dielectric loaded waveguide

The effect of broadening the bandwidth with a dielectric load in a cylindrical gyrotron is investigated for a hollow electron beam. The linear dispersion relation for the azimuthally symmetric, transverse electric (TE) modes is obtained by the method of the wave impedance matching. It is found that the TE perturbations exhibit three unstable modes characterized by their phase velocities vph : one fast wave, the long wavelength mode (LWM, vph ≳c), and two slow waves, the intermediate (IWM, c≳vph ≳cε−1/2) and the short (SWM, vph <cε−1/2) wavelength modes. The optimum conditions for the wide band operation are obtained individually for each mode. Although the bandwidth in excess of 40% is possible for the slow waves (IWM, SWM) at a small axial momentum spread, it decreases rapidly as the spread increases. On the other hand, the LWM yields approximately 10% of the bandwidth insensitive to the spread. It is also shown that for a small spread (<5%), the slow wave (IWM) is preferable for the wide band operation, whereas for a large spread (≳5%) the fast wave (LWM) is desirable.

Shock compression of liquid argon, nitrogen, and oxygen to 90 GPa (900 kbar)

Dynamic equation-of-state data for liquid Ar, N2, and O2 were measured in the shock pressure range 21–91 GPa (210–910 kbar) by means of a two-stage light-gas gun. The liquids were shocked from initial states near their saturation curves at 0.1 MPa (1 bar) and 80 K. The cryogenic target system is described. The initial liquid densities were obtained by measuring the temperature and pressure of the specimens and calculating the densities from published equations of state. Shock velocities were measured to 0.5–1.1% accuracy with an electronic detection system with subnanosecond time resolution. Impactor velocities in the range 4–7 km/s were measured to 0.1% accuracy with a flash radiographic technique. Mass velocities were obtained by the method of shock impedance matching. The data are discussed in terms of the statistical–mechanical theories of Ross and Ree.

Probe-tube microphone for pressure-fluctuation measurements in harsh environments

A probe-tube microphone has been developed for use in the harsh experimental environment involved in studying small-scale pressure fluctuations in combustion magnetohydrodynamics. A smooth frequency response is obtained by a theoretically derived method of impedance matching where an acoustical resistance is placed midway within the length of the tube. The use of such probe-tube microphones under experimental conditions has proven very satisfactory.

Broad-band impedance matching of rectangular waveguide phased arrays

A method for wide-band wide-angle impedance matching of rectangular waveguide phased arrays is presented. A maximum VSWR of 2.3:1 is achieved over a 50 percent bandwidth with a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">60\deg</tex> half-angle conical coverage using an element spacing six percent less than the condition required for grating lobe suppression. A further reduction in element spacing, bandwidth, or scan volume results in an even better impedance match. Simplicity and high radiation efficiency are the unique features of this matching technique.

Shock Wave Compression of Benzene, Carbon Disulfide, Carbon Tetrachloride, and Liquid Nitrogen

Hugoniot data to several hundred kilobar have been obtained for benzene, carbon disulfide, carbon tetrachloride, and liquid nitrogen. Standard high explosive techniques were used for generating the shock waves. Experimentally measured quantities were transformed to pressure and volume data by the impedance match method. The shock-particle velocity data for the liquids are described by a linear relationship, however, a quadratic in particle velocity also provides an adequate representation of the data for carbon tetrachloride and liquid nitrogen. Benzene undergoes a transition at 133 kbar and carbon disulfide at 62 kbar. These transitions are accompanied by a volume decrease of approximately 16%. A double shock-wave structure, observed in many solids which undergo a transition, was not observed in benzene and carbon disulfide. There is some evidence that carbon tetrachloride and liquid nitrogen undergo a transition at 165 and 135 kbar, respectively. Hugoniot curves calculated from a Lennard-Jones and Devonshire (6-9) and a modified Buckingham exp-6 intermolecular potential fit the liquid nitrogen experimental Hugoniot curve between 20 and 170 kbar.

Wide-angle impedance matching of a planar array antenna by a dielectric sheet

For wide-angle scanning array antennas, the magnitude of the reflection changes substantially with scan angle and wave polarization. Conventional matching techniques in the individual element feed lines cannot compensate for these changes. There is a method of wide-angle impedance matching (WAIM) which utilizes a thin, high- <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</tex> , dielectric sheet spaced in front of the array. It is capable of equalizing the reflection coefficient for <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</tex> polarization at any specified scan angle, or for any angle in the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">E</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</tex> scan planes. This technique is applied to an array having element aperture windows flush with a metal face. It is adapted for the procedure of matching in a waveguide simulation of an infinite array.

Conjugate-Image Impedances

A load having the conjugate impedance of the signal generator to which it is connected receives the maximum amount of power and is said to be matched on the conjugate-image basis. This method of impedance matching, when applied to active and passive four-terminal networks, is shown to be especially suitable for determining the limits of power amplification or loss. In contrast, an analysis on the usual image basis gives these results only if the image impedances happen to be pure resistances. The maximum power gain of a given network and the impedance terminations for achieving it are derived and are expressed in-concise form. The effects of impedance mismatching are likewise treated.