Effect Of Dc Magnetic Field Research Articles

Effects of DC magnetic field upon the properties of a HTS microstrip antenna at 4.2 K

Abstract A circular polarized microstrip antenna with a working frequency of 6.26 GHz was fabricated from YBCO HTS films. The transmission coefficient and circular polarization ratio of the antenna at different external magnetic field B were measured at 4.2 K. The experimental results showed that its transmission coefficient and circular polarization ratio hardly changed with B up to 1 T. It is concluded that the field-induced increase of surface resistance of YBCO films would not influence the microwave properties of this antenna at B ⩽ 1T and T = 4.2 K.

Analysis of planar superconducting waveguides in DC magnetic field

A theoretical analysis of microwave properties of planar superconducting waveguides of finite thickness in the presence of an external dc magnetic field is presented in this article. Some analytical formulas are derived for determining the attenuation and dispersion properties of the superconducting waveguide, which may account for the effects of the dc magnetic field, the electrodynamic properties of type-II superconductors, the thickness of superconducting films, and the dielectric loss in the waveguide. Numerical results are then given to show quantitatively how the dc magnetic field influences the propagation properties of the planar superconducting waveguide. Some analysis are also given to study the effect of dc magnetic field on the quality factorQ and the resonant frequency of planar superconducting waveguide resonators.

The physics of the environmental sensitivity of rubidium gas cell atomic frequency standards

The physical mechanisms behind environmental sensitivity are considered, and they are related to the performances of rubidium frequency standards (RFSs). Some of the RFS environmental sensitivities are due to simple physical mechanisms like the effect of DC magnetic field on the Rb hyperfine resonance frequency. For these, an analysis can be based on physical principles and straightforward design factors. Other environmental factors, like temperature sensitivity, are more complex combinations of many effects, both physical and practical, and the analysis often takes the form of an error budget, with large unit-to-unit variations. Today's RFSs span a wide performance range from small, inexpensive units with pp10(10) error budgets to larger, higher-performance versions offering pp10(14) stabilities. For both extremes, however, environmental sensitivity can be the most significant performance limitation. Why this is the case is explained, and some insight into how to make improvements is offered.

Phase locking of long Josephson junctions.

We present numerical simulations on the phase locking of solitons in long Josephson junctions by the application of external microwave signals. The full partial differential equation with boundary conditions has been used. Overlap and inline geometries are considered; the effects of dc magnetic fields and different configurations of the rf field have also been investigated.

Combustion Processes Under Intense Magentic Fields

As a means of clarifying the effect of dc magnetic fields on oxidation reactions in living organisms, the authors studied combustion phenomena in air. In one experiment, benzine was injected into four Pt body warmers, which were ignited with two exposed to a graded dc magnetic field (1.0 T, 10 T/m); the combustion time of the exposed group was 16 percesnt shorter on average. In another experiment, two body warmers were placed at the poles of an electromagnet and ignited, and combustion times measured, turning the magnet on and off; combustion times were 15.6 percent shorter on average when exposed to the field.

Effect of homogeneous magnetic fields on responses to toxic stimulation in spirostomum ambiguum

Effects of DC magnetic fields, up to 125,000 G, on the survival of the ciliated protozoan Spirostomum ambiguum exposed to the toxic substance 2,2'-dipyridyldisulfide are reported. The magentic field diminishes the ability of the organism to survive the drug, and lengthens the extension phase of the contraction cycle. It is proposed that the magnetic field alters the regulation of intracellular (Ca2+) transients.