Effect Of Magnetic Field Variation Research Articles

The effect of magnetic field variations on the spectral properties of tornado plasma

At atmospheric pressure and at a frequency of 9.1 kHz, a constructed magnetically stabilized tornado gliding arc discharge (MSGAD) system was utilized in this study to generate a non-thermal plasma with an alternating voltage source from 2,4,6,8 to 10 kV. Argon gas was used to generate the arc plasma with an adjustable flow rate using a flow meter regulator to stabilize the gas flow rate to 2 L/min. A gliding plasma discharge is achieved by a magnetic field for the purpose of a planned investigation. The influence of the magnetically stabilized tornado gliding arc discharge parameters such as magnetic field and applied voltage on microscopic tornado plasma parameters was studied. The electron temperature1was measured using a Boltzmann plot and the electron1density was1determined by the Stark1broadening method. The electron temperature ranged from 0.818 eV to 1.495 eV, and the electron density varied from 1.37 × 1018 cm−3 to 2.49 × 10 18 cm−3 at a magnetic coil with 350 turns. Subsequently, the electron temperature increased to a range of 1.029 eV–1.794 eV, and the electron density reached a range of 1.53 × 1018 cm−3 to 2.89 × 1018 cm−3 at a magnetic coil with 500 turns. It can be observed that the plasma properties exhibit a rise as the number of turns of the coil and the applied voltage increase.

The effect of magnetic field variations in a mixture of coconut oil and jatropha on flame stability and characteristics on the premixed combustion

This study investigates the effect of attracting and repels magnetic fields with the materials of vegetable oil in the form of a mixture of coconut oil and jatropha (B50) against the behavior of stability and characteristics of flame in the process of premixed burning. The fuel for a mixture of vegetable oil of 600 ml was filled into the boiler heated with a gas stove to be evaporated at a temperature of 300 °C and 3 bar pressure was kept constant was mixed with air from the compressor in the burner room. Then a flame was ignited at the end of the nozzle to form a diffusion flame, the flame formed was then given north (N) and south (S). The results showed that the flame speed of the attractive magnetic field was 52.22 cm/sec, the repulsive magnetic field was 50.49 cm/sec while without a magnetic field was 49.79 cm/sec. The increase in the laminar flame speed in the attractive magnetic field is caused by the electron spin becoming more energetic and due to the change in the spin of the hydrogen proton from para to ortho. The attractive magnetic field has the strongest effect on increasing the flame speed. This makes the flame more stable in the equivalency ratio range of 0.75–1.17 compared to without a magnetic field in the same equivalency ratio range. This was so because O2 where it is in nature of paramagnetic was pumped more crossing the flame from south to north poles whereas the heat brought by H2O in nature of diamagnetic was pumped more crossing north to south poles. Whereas on the repel magnetic field, it was hotter when brought by H2O pumped into the flame whereas O2 tended to be pumped going out of the flame. This caused the combustion in the flame was smaller and the reaction was not maximum. As a consequence, the laminar flame speed was more lacking and the reaction was not to the fullest. As a consequence, the laminar flame speed in the repel was fewer than the attract magnetic field

On the observation of magnetic events on broad-band seismometers

The objective of this contribution is to get new insights into the effects of magnetic field variations of natural and anthropogenic origin on broad-band seismic stations. Regarding natural sources of magnetic perturbations, we have investigated if the Sudden Storm Commencements (SSC) cataloged during the 24th solar cycle (2008–2019) can be systematically identified in broad-band seismic stations distributed worldwide. The results show that the 23 SSC events with a mean amplitude above 30 nT and most of those with lower energy but still clearly identified in the magnetometer detection network can be observed at broad-band stations’ network using a simple low-pass filter. Although the preliminary impulse of those signals is usually stronger at stations located at high latitudes, major SSC are observed at seismic stations distributed worldwide. Regarding anthropogenic sources, we focus on the short period seismic signals recorded in urban environments which are correlated with the activity of the railway transportation system. We have analyzed collocated measurements of electric field and seismic signals within Barcelona, evidencing that significant changes in the electric field following the activity of the transportation systems can be attributed to leakage currents transmitted to the soil by trains. During space weather events, electric currents in the magnetosphere and ionosphere experience large variations inducing telluric currents near the Earth surface, which in turn generate a secondary magnetic field. In the case of underground trains, leakage currents are transmitted to the soil, which in turn can result in local variations in the magnetic field. The observed signals in modern seismometers can be related to the reaction of the suspension springs to these magnetic field variations or to the effect of the magnetic field variations on the force transducers used to keep the mass fixed.

Effects of the magnetic field variation on the spin wave interference in a magnetic cross junction

This article reports results of the investigation of the effect of the external magnetic field variation on the spin wave interference in a magnetic cross junction. The experiments were performed using a micrometer scale Y3Fe5O12 cross structure with a set of micro-antennas fabricated on the edges of the cross arms. Two of the antennas were used for the spin wave excitation while a third antenna was used for detecting the inductive voltage produced by the interfering spin waves. It was found that a small variation of the bias magnetic field may result in a significant change of the output inductive voltage. The effect is most prominent under the destructive interference condition. The maximum response exceeds 30 dB per 0.1 Oe at room temperature. It takes a relatively small bias magnetic field variation of about 1 Oe to drive the system from the destructive to the constructive interference conditions. The switching is accompanied by a significant, up to 50 dB, change in the output voltage. The obtained results demonstrate a feasibility of the efficient spin wave interference control by an external magnetic field, which may be utilized for engineering novel type of magnetometers and magnonic logic devices.

Controlling precise magnetic field configuration around electron cyclotron resonance zone for enhancing plasma parameters and beam current

Multi-charged ion source which has wide operating conditions is required in various application fields. We have constructed tandem type ECR ion source (ECRIS); one of the features of its main stage is an additional coil for controlling magnetic field distribution around the mirror bottom precisely. Here the effect of magnetic field variation caused by the additional coil is experimentally considered in terms of plasma parameters and beam current as the first investigation of the main stage plasma. Furthermore, behavior of magnetic lines of force flowing from the ECR zone is calculated, and is compared with measurement results aiming for better understanding of interrelationship between plasma production and ion beam generation on the ECRIS.

MHD Stability of Streaming Jet Using Artificial Intelligence Technique

AbstractMathematical formulation for Magnetohydrodynamic (MHD) stability of a streaming cylindrical model penetrated by varying transverse magnetic field is presented. Eigen value relation is derived and discussed analytically. In the current paper, Artificial Neural Network (ANN) model, one of the artificial intelligence techniques, is developed to simulate the stability of streaming jet penetrated by magnetic field. The ANN results presented in the current study showed that ANN technique, with less effort and time, is very efficiently capable of simulating and predicting the effect of magnetic field variation and axial exterior field on the stability of the streaming jet. The influence of magnetic field has a stabilizing effect for all short and long wavelengths. However the streaming is strongly destabilizing.

Viscosity Measurement Cell Utilizing Electrodynamic-Acoustic Resonator Sensors: Design Considerations and Issues

Abstract Miniaturized resonating viscosity sensors operating at frequencies in the low KHz-range offer portability and results comparable to existing lab viscometers. In this paper we will briefly describe a viscosity measurement cell based on a concept that we proposed earlier utilizing electrodynamic-acoustic resonator sensors with a design based on interchangeable resonator cards, which allow for ease of maintenance of the device and provides higher measurement repeatability. Experimental results obtained with the new resonator cards show the clear dependence of the resonance frequency and Q factor on viscosity. In addition, an experimental approach is taken to study the effects of magnetic field variations on the Q factor of the investigated resonators which are suspended by S-shaped (meander) beams and operating either in air or liquids.

Gradiometric investigation of a cesium-vapor quantum magnetometer

Experiments aimed to determine the sensitivity and the optical shift of the output frequency of a magnetometer based on optical pumping of cesium atoms and intended for a neutron magnetic resonance stabilization system are described. A gradiometric arrangement used in these experiments makes it possible to reduce the effect of magnetic field variations on measurements.

Cerebral oxygen extraction fraction and cerebral venous blood volume measurements using MRI: effects of magnetic field variation.

The presence of magnetic background field inhomogeneity (DeltaB) may confound quantitative measures of cerebral venous blood volume (vCBV) and cerebral oxygen extraction fraction (MR_OEF) with T2*-based methods. The goal of this study was to correct its effect and obtain more accurate estimates of vCBV and MR_OEF. A 3D high-resolution gradient echo sequence was employed to obtain DeltaB maps by two algorithms. The DeltaB maps were then used to recover the signal loss in images acquired by a 2D multiecho gradient echo / spin echo sequence. Finally, both quantitative estimates of MR_OEF and vCBV were obtained from the DeltaB- corrected 2D multiecho gradient echo / spin echo images. A total of 12 normal subjects were studied. An overestimated vCBV was observed in the brain (4.29 +/- 0.78%) prior to DeltaB correction, while the measured vCBV was substantially reduced after DeltaB correction. Whole brain vCBV of 2.97 +/- 0.44% and 2.68 +/- 0.47% were obtained by the two different DeltaB correction methods, in excellent agreement with the reported results in the literature. Furthermore, when MR_OEF was compared with and without DeltaB correction, no significant differences (P = 0.467) were observed. The ability to simultaneously obtain vCBV and MR_OEF noninvasively may have profound clinical implications for the studies of cerebrovascular disease.

Gyrokinetic theory of perpendicular cyclotron resonance in a nonuniformly magnetized plasma

The extension of gyrokinetic theory to arbitrary frequencies by Chen and Tsai [Phys. Fluids 26, 141 (1983); Plasma Phys. 25, 349 (1983)] is used to study cyclotron absorption in a straight magnetic field with a perpendicular, linear gradient in strength. The analysis includes the effects of magnetic field variation across the Larmor orbit and is restricted to propagation perpendicular to the field. It yields the following results for propagation into the field gradient. The standard optical depths for the fundamental O-mode and second harmonic X-mode resonances are obtained from the absorption profiles given in this paper, without invoking relativistic mass variation [see also Antonsen and Manheimer, Phys. Fluids 21, 2295 (1978)]. The compressional Alfvén wave is shown to undergo perpendicular cyclotron damping at the fundamental minority resonance in a two-ion species plasma and at second harmonic resonance in a single-ion species plasma. Ion Bernstein waves propagating into the second harmonic resonance are no longer unattenuated, but are increasingly damped as they approach the resonance. It is shown how the kinetic power flow affects absorption profiles, yielding information previously obtainable only from full-wave theory. In all cases, the perpendicular cyclotron damping arises from the inclusion of magnetic field variation across the Larmor orbit.

31P magnetic resonance spectroscopy of the normal human brain: approaches using four dimensional chemical shift imaging and phase mapping techniques.

The use of four-dimensional chemical shift imaging to monitor phosphorus metabolites within the human brain is illustrated. Saturation effects are described, and acquisition conditions are discussed in relation to quantification and sensitivity. The effects of magnetic field variations on spectral parameters are assessed and the use of a field mapping technique is illustrated.

A method for the spatial reconstruction of bubble chamber tracks

A spatial reconstruction method for bubble chamber tracks is described, which requires a minimum number of measurements, involves a relativeiy simple computation, and yields results of a precision comparable to those obtained by more complex methods. The method is based on the fact that the properties of a track in a bubble chamber can be determined quite accurately from knowledge of the coordinates of three points on the track. The three space points are used to determine the parameters of a helix. Corrections can be made for the effects of magnetic field variations and energy loss. (A.G.W.)