Electric field distribution in a cylindrical TM010 microwave cavity with end holes and a glass tube

Pipisková, A

doi:10.1088/0022-3727/3/9/321

Cited by 5 publications

(3 citation statements)

References 20 publications

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“…The theoretical electric field intensity distribution in a closed, unperturbed (without the holes and a glass tube) cylindrical T M 010 microwave cavity is proportional to the zero-order Bessel function in the radial direction. In our previous paper (Pipišková, and Lukáč [34]) we have shown that a glass tube affects the electric field configuration and the electric field intensity in a cylindrical T M 010 microwave cavity which in turn modifies the absolute electron density value determination. We have carried out the same measurement in the first experimental dual mode set up, for the S-band microwave range.…”

Section: Electron Density Measurementsmentioning

confidence: 97%

The Dual Mode Microwave Afterglow Apparatus for Measuring the Electron Temperature Dependence of the Electron‐Ion Recombination

Mikuš

Morva

Morvová

et al. 2008

Contrib. Plasma Phys.

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Key words Stationary afterglow plasma, microwave diagnostics of plasma, electron heating with microwaves, dissociative recombination, electron temperature dependence of recombination, molecular neon ions. PACS 34. 80, 52.20, 52.70 Three dual mode microwave apparatus (one using S-band and two using X-band) have been developed to determine ambipolar diffusion and electron-ion recombination rates under conditions such that Tgas = 300K and Te is varied from 300 K to 6300 K, in the afterglow period of the dc glow discharge. The T M010 cylindrical cavity (in S-band) and T M011 open cylindrical cavity (X-band) are used to determine the electron density during the afterglow period and a non-resonant waveguide mode is used to apply a constant microwave heating field to the electrons. To test the properties of the apparatus the neon afterglow plasma has been investigated. At Te = 300 K a value of α(Ne (X-band) obeyed over the range 300 ≤ Te ≤ 6300K are in good agreement with some other previous measurements. The simplicity of the X-band microwave apparatus also allows the measurements of the gas temperature dependency and the study of electron attachment and may be used simultaneously with optical or mass spectrometry investigations.

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Section: Electron Density Measurementsmentioning

confidence: 97%

The Dual Mode Microwave Afterglow Apparatus for Measuring the Electron Temperature Dependence of the Electron‐Ion Recombination

Mikuš

Morva

Morvová

et al. 2008

Contrib. Plasma Phys.

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“…24 This work showed that errors may range from a few percent to one hundred percent if samples are probed in the iris region.…”

Section: Awmentioning

confidence: 96%

Microwave properties of liquids and solids using a resonant microwave cavity as a probe

Hong

Roberts

1974

Journal of Applied Physics

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The frequency shifts and Q changes of a resonant microwave cavity were utilized as a basis for determining microwave susceptibilities and loss tangents for solids and liquids. The method employed consisted of varying the depth of penetration of a continuous cylindrical sample of the material into a cavity operating in the TM010 mode with the resonant frequency and quality factor determined at each incremental setting of the perturbing sample. The perturbation of the cavity was achieved by advancing the sample into the cavity along the symmetry axis by employing a micrometer drive appropriately calibrated for depth of penetration of the sample. A differentiation method was used to obtain the half-power points of the cavity resonance profile at each depth of penetration. The perturbation techniques for resonant cavities were used to reduce the experimental data obtained to physical parameters for the samples. The probing frequency employed was near 10 GHz.

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“…In a perfect empty and sealed cylindrical cavity there is no electric field variation in vertical direction. Modelling by Pipiskova & Lukac (1970) At this point the measurement technique diverges. Room temperature measurements only require another measurement of the centre frequency and bandwidth of the resonant modes and then the sample is discarded and the process begins with a fresh sample tube and kaolin-wool plug.…”

Section: Measurement Proceduresmentioning

confidence: 99%

Novel techniques in ore characterisation and sorting

Genn¹

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Ore sorting is becoming increasingly important to the minerals industry but is a difficult technology to apply effectively to many ore types. Microwave excitation and infrared detection (MW/IR) is a potential new sensor technology for sorting copper sulphide ores.This technology utilises the high dielectric permittivity of copper sulphide minerals and relatively low dielectric properties of gangue minerals to selectively heat copper rich particles and thereby gauge particle grade from temperature. To date, the dielectric properties of minerals and the role of mineral structures within particles are not fully understood and can vary significantly from deposit to deposit due to differences in geochemistry and genesis.These variations in mineralogy and dielectric properties can mean that some ores are unsuitable for sorting. The aim of this thesis is to develop a characterisation methodology to assess the suitability of ores for MW/IR based sorting from small sets of particles.The microwave heating of six different ores, chosen to represent a range of minerals and mineral textures, was characterised using randomly split particles, a domestic microwave oven and thermal imaging. The dielectric properties of core and powder subsamples of particles from four ores were then measured using a resonant cavity perturbation experiments at The University of Nottingham. Three effects were identified that may influence the observed relationship between microwave heating and dielectric properties: strong interaction with the magnetic field, mineral structures and sulphide heterogeneity in samples. These effects were investigated using radiofrequency magnetic permeability measurements, rotation of rock cylinders in a rectangular waveguide resonant cavity and automated scanning electron microscopy (MLA). The modal mineralogy of ore samples was measured using MLA while geochemistry was investigated using electron probe microscopy. The dielectric properties of mineral groups were then calculated using systems of linear equations based on the LandauLifschitz-Looyenga mixture equation as well as modal mineralogy and dielectric property data. Finally, numerical simulations of microwave heating were performed using data on mineralogy, mineral dielectric properties and variability in particle heating to determine to assess the potential of rocks types for sorting.ii MW/IR characterisation showed that quartzite, monzonite and skarn ores have distinct particle temperature distributions and that variation in the pixel temperatures of individual particle surfaces might be useful in distinguishing particle petrology. A power law was found to describe the relationship between microwave heating and dielectric loss tangent (R 2 = 79%) although a good fit could be achieved with a linear relationship (R 2 = 89%) when specific, termed anomalous, particles were excluded. Magnetic permeability measurements indicated that there was no significant difference in permeability between normal and anomalously heating particles. Changes in cavity per...

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Electric field distribution in a cylindrical TM010 microwave cavity with end holes and a glass tube

Cited by 5 publications

References 20 publications

The Dual Mode Microwave Afterglow Apparatus for Measuring the Electron Temperature Dependence of the Electron‐Ion Recombination

The Dual Mode Microwave Afterglow Apparatus for Measuring the Electron Temperature Dependence of the Electron‐Ion Recombination

Microwave properties of liquids and solids using a resonant microwave cavity as a probe

Novel techniques in ore characterisation and sorting

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