Azimuthal Nonuniformity Research Articles

Nonsteady heat and mass transfer with azimuthal nonuniformity of the heat supply to bundles of spiral tubes

The nonsteady mixing of heat carrier in a bundle of spiral tubes with azimuthal nonuniformity of the heat supply is considered. The peculiarities of the solution of this problem using a two-temperature model of the flow of homogenized two-phase medium with motionless solid phase are shown. The nonsteady temperature fields of the heat carrier are investigated experimentally for the case of sharp increase and decrease in the thermal-load power over time. Recommendations are given regarding the calculation of the nonsteady coefficients used to close the initial system of equations.

The influence of buoyancy on thermophoretic deposition of aerosol particles in a horizontal tube

Abstract The transport and deposition of aerosol particles in a horizontal tube with a linear wall temperature profile are analyzed. Assuming fully developed velocity and temperature fields, and using trajectory calculations, the deposition efficiency is calculated as a function of system parameters. It is found that buoyant flows tend to increase the rate of deposition of particles on the tube wall. Also, such flows can lead to azimuthal nonuniformity in the deposition process.

Azimuthal non-uniformities induced by ICH and ECH in the RFC-XX mirror plasma

The loss flux to an azimuthally segmented limiter in the central cell of the cusp end cell stabilized, axisymmetric mirror machine, RFC-XX, shows that non-axisymmetric illumination by either ICH or ECH can induce azimuthal non-uniformities in the plasma. Measurements of the floating potential in the vicinity of the limiter and by the limiter itself suggest that a large stationary azimuthal electric field is induced which can convectively transport plasma across magnetic field lines. The local radial component of the electric drift velocity is as large as 7 × 104 cm·s−1. Examinatio n of the plasma end loss versus azimuth and probe measurements deep in the plasma show that the non-uniformities extend into the plasma and are not localized near the outer boundary. The data suggest that the RF fields are driving an anomalous radial loss.

Effect of azimuthal nonuniformity of magnetic field of synchrotron of state special standard of energy-luminance spectral density at 50?250 nm on error of unit reproduction

The structure of the state special standard of the unit of energyluminance spectral density (ELSD) in the wavelength range of 50-250 nm was examined, its main elements were described, and the errors arising in transmission of the ELSD unit were analyzed. The error component of ELSD-unit reproduction due to azimuthal magnetic-field nonuniformity does not exceed 3.10/sup -3/. This makes it possible to use in calculation of the coefficent presented integral orbit characteristics such as average obit radius P and average magnetic field in orbit H=H(p) without substantially increasing the aggregate error.

Azimuthal nonuniformities in the pumping distribution in an elliptical housing

Azimuthal nonuniformities in the pumping distribution in an elliptical housing

Instability of a hot-cathode discharge in a magnetic field at low pressures

The authors present results of the investigation of an incandescent-cathode discharge in an equipotential volume in a magnetic field of 2000 Oe. In the pressure range studied, 2 × 10−6 to 10−4 Torr, there is formed a plasma column negatively charged in relation to the surrounding walls. It is established that, when the pressure of the neutral gas is increased, such a discharge becomes unstable. A plasma torch is formed which rotates steadily in the direction of the electrons and escapes from the region of the primary beam. The torch is a result of plasma polarisation in the primary electron beam when there is azimuthal non-uniformity of density and a difference between the ion and electron drift velocities. If the pressure is increased further the steady rotation vanishes and intensive oscillations with a continuous frequency spectrum develop in the discharge. The fundamental principles underlying this discharge behaviour are explained. By means of a simplified model an expression for the rotation frequency of the torch is obtained and confirmed qualitatively by experiment.

EFFECT OF MAGNETIC FIELD NONUNIFORM ITIES ON THE PERFORMANCE OF DOUBLE-FOCUSING MASS SPECTROMETERS

The effects of magnetic field nonuniformities on the focusing properties of the three types of magnetic field sectors commonly employed in mass spectrometers and spectrographs are discussed. Two types of magnetic field non-uniformities are considered: those in which the vertical component of the magnetic field, Bz, varies along the central ion path ("azimuthal nonuniformities") and those in which Bz is a function of the displacement in the direction normal to the central ion path ("radial nonuniformities"). To facilitate the interpretation of results, the ions entering the magnetic field are assumed to have the velocity dispersion required to form a velocity focus at the position of the direction focus (i.e., to give a double focus), if the magnetic field were uniform.