Frequency Of AC Signal Research Articles

An iterative calculation of galvanomagnetic coefficients and a.c. conductivity of polar semiconductors

An iteration procedure is presented for the calculation of AC and galvanomagnetic transport coefficients of polar semiconductors. Computational results are also given which indicate that the method is convergent and that the rate of convergence is faster for larger values of magnetic field and AC signal frequencies.

The theory and application of conductance probes for the measurement of liquid film thickness in two-phase flow

The thickness of a rapidly moving, wavy film of water can be continuously measured and recorded using a probe, which consists of two surface-mounted parallel conductors across which a high frequency AC signal is applied. A theory is given which allows prediction of the electrical conductance of the probe as a function of the film thickness and shows how the useful range of particular probe designs can be assessed. The theory, which can be applied to probes in either flat or curved surfaces, also includes the effect of a step change in the film thickness, so that the resolution of the probe may be predicted.

Wave-Excited Anomalous Diffusion in a Fully Ionized Magnetoplasma

The transverse diffusion coefficient D⊥ of a fully ionized plasma in a Q machine was observed to depend on the frequency and amplitude of low-frequency (kilocycle) waves. These waves, observed with a floating Langmuir probe and spectrum analyzer, could be impressed on the plasma (1) by a weak electron beam injected along the plasma axis, (2) by applying an ac signal of appropriate frequency to a plate at one end of the plasma, or (3) were found to occur naturally. D⊥ was determined from the radial profile of potassium plasma pulses. In all cases, D⊥ was strongly influenced by the amplitude of the low-frequency components of the spectrum and was observed to be proportional to the rms power of the fluctuations. The impedance of the plasma as a function of the impressed ac signal showed minima at frequencies close to that of the ``drift instability,'' where the value of D⊥ exhibited strong maxima.

Electromagnetic Interference Control Within Aerospace Ground Equipment for the Mcdonnell Phantom II Aircraft

This paper describes the program conducted by McDonnell Aircraft Corporation to assure Electromagnetic Compatibility (EMC) within Aerospace Ground Equipment (AGE) for tile Phantom II Aircraft. The wide variety of sophisticated AGE utilized presents many unique EMC problems. AGE/Aircraft compatibility considerations at McDonnell are of prime concern. Consistent grounding philosophies within AGE and compatible with airborne equipment has been established. Grounding systems are classified as primary power, secondary AC power, DC power, signal and radio frequency. Each equipment ground is classified and controlled accordingly. A Weapon System concept that results in the extensive use of shielded cabling is an important part of the McDonnell Aircraft EMI control approach. Design and testing of shielded cables, connectors, and connector back-shells has been accomplished. New designs to reduce radiation from various front panel mounted switches, jacks, meters, and lights have been developed. These include the grounding of "Bat" handles and shafts of switches and using waveguide below cut-off devices for jacks. Testing complex AGE to determine compliance with Military Specifications can become very time consuming. Methods and procedures to reduce test time, yet maintain a valid test, have been formulated.