Effect of the Longitudinal Magnetic Field on the Electrical Breakdown in Argon and Nitrogen Plasma Discharges (original) (raw)
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International Journal of ADVANCED AND APPLIED SCIENCES
In this paper the electrical breakdown has been described for low-pressure argon discharges under the influence of an external longitudinal magnetic field. Plane-parallel stainless steel electrodes (7.25 cm diameter) are sustained with a dc voltage (0<V<1 kV), the pressure was varied between 0.4 mbar and 2.6 mbar and the inter-electrode distance 2.0 cm. A Helmholtz coil was used to produce a uniform magnetic field (B=270G) from an inductive copper coil of diameter (1mm). A Paschen curve has been obtained and the first Townsend ionization coefficient (α), the secondary electron emission coefficient (γ) and the ionization efficiency (η) were plotted with respect to the variation of the reduced field (E/P). The calculated value of the η (E/p) and γ (E/p) inside the magnetic trap is in good agreement with the previous literatures results.
Longitudinal magnetic field effect on the electrical breakdown in low pressure gases
Brazilian Journal of Physics, 2004
The electrical breakdown has been investigated for low-pressure argon and nitrogen discharges under the influence of an external longitudinal magnetic field. Plane-parallel aluminum electrodes (5 cm diameter) separated by a variable distance d (4.0 cm < d < 11.0 cm) were sustained with a dc voltage (0 < V < 1 kV). A Helmholtz coil was used to produce an uniform magnetic field(B) parallel to the discharge axis. Paschen curves were obtained and the secondary electron emission coefficient (γ), the first Townsend ionization coefficient (α) and the ionization efficiency(η), were plotted with respect to the variation of the reduced field (E/P). To observe the effect of the magnetic field these curves were plotted for fixed values of B=0 and B=350 Gauss. As consequence of the longitudinal magnetic field, the free paths of the electrons in the Townsend discharge are lengthened and their lateral diffusion is reduced, thus reducing electron losses to the walls. The data presented in this paper give a quantitative description of the B-field effect on the Townsend's coefficients and overall it is concluded that the DC electrical breakdown of the gases is facilitated if a longitudinal magnetic field is applied along the discharge axis.
Iraqi Journal of Science
This work is an experimental study about the effects of gas pressure and magnetic field on plasma characteristics produced in an internal hollow electrodes discharge (HED) system. The results show that the breakdown voltage values increase with increasing the working pressure (especially with the presence of a magnetic field). The breakdown voltage depends on the p.d. product, where p is the gas pressure and d is the distance between the electrodes. While the values of current discharge decrease with the increase of the working pressure. The temperature of electron and the number density of electron are calculated from the Boltzmann method and the broadening of Stark, respectively. The results showed that the electron number density ( ) and plasma frequency ( ) increase with increasing the gas pressure, especially with the presence of a magnetic field, i.e. the plasma is more stable with the presence of magnetic field. While the electron temperature ( ) and Debye length ( ) de...
Modeling and Diagnostic of the Plasma of Magnetic Field Supported Discharges
Contributions to Plasma Physics, 2005
In this paper we present an experimental study of the variations of plasma parameters in both the axial as well as in radial directions in a 30 cm long cylindrical magnetron with outer cylindrically-shaped anode (diameter 58 mm) and coaxially placed cathode with a diameter of 1.8 cm. The measurements were made using three radially movable cylindrical Langmuir probes placed at three different axial positions between the magnetic coils. From the measurements there were evaluated electron density, electron mean energy, plasma potential and floating potential in dependence of the magnetic field (10-40 mT) and the argon pressure (2-7 Pa). In order to measure the axial variations of the discharge current, one half of the cathode length is segmented into 14 isolated segments with length of about 10 mm. The physical processes occurring in electrode regions and the positive column of a cylindrical magnetron discharge in crossed electric and magnetic fields are investigated basing on the solution of the Boltzmann kinetic equation by a multiterm decomposition of the electron phase space distribution function in terms of the spherical tensors. The influence of the distribution function anisotropy on the absolute values and radial profiles of the electron density and rates of various transport and collision processes is analyzed. The spiral lines for the directed particle and energy transport are obtained to illustrate the anisotropy effects in dependence on magnetic field. The electron equipressure surfaces are constructed in the form of ellipsoids of pressure and their transformation in the cathode and anode regions is studied. A strong anisotropy of the energy flux tensor in contrast to a weak anisotropy of the momentum flux density tensor is found. Particular results are obtained for the cylindrical magnetron discharge in argon at pressure 3 Pa, current 200 mA and magnetic fields ranging within 10 − 40 mT.
Measurements of Some Argon Plasma Parameters Glow Discharge Under Axial Magnetic Field
2019
This paper investigates the characteristics some of argon plasma parameters of glow discharge under axial magnetic field. The DC power supply of range (0-6000) V is used as a breakdown voltage to obtain the discharge of argon gas. The discharge voltagecurrent (V-I) characteristic curves and Paschen’s curves as well as the electrical conductivity were studied with the presents of magnetic field confinement at different gas pressures. The magnetic field up to 25 mT was obtained using four coils of radius 6 cm and 320 turn by passing A.C current up to 5 Amperes. Spectroscopic measurements are employed for purpose of estimating two main plasma parameters electron temperature (Te) and electron density (ne). Emission spectra from positive column (PC) zone of the discharge have been studies at different values of magnetic field and pressures at constant discharge currents of 1.5 mA. Electron temperature (Te) and its density are calculated from the ratio of the intensity of two emission lin...
Measurement of Some Argon Plasma Parameters Glow Discharge Under Axial Magnetic Field
2019
This paper investigates the characteristics some of argon plasma parameters of glow discharge under axial magnetic field. The DC power supply of range (0-6000) V is used as a breakdown voltage to obtain the discharge of argon gas. The discharge voltage-current (V-I) characteristic curves and Paschen’s curves as well as the electrical conductivity were studied with the presents of magnetic field confinement at different gas pressures. The magnetic field up to 25 mT was obtained using four coils of radius 6 cm and 320 turn by passing A.C current up to 5 Amperes. Spectroscopic measurements are employed for purpose of estimating two main plasma parameters electron temperature (Te) and electron density (ne). Emission spectra from positive column (PC) zone of the discharge have been studies at different values of magnetic field and pressures at constant discharge currents of 1.5 mA. Electron temperature (Te) and its density are calculated from the ratio of the intensity of two emission li...
Contributions To Plasma Physics, 2004
Two similar experimental set-ups were used to measure axial and radial distribution of discharge plasma parameters at different magnetic fields. Both systems were cylindrical magnetrons with outer cylindrically-shaped anode and coaxially placed cathode – both the discharge vessels had diameters approximately 6 cm and they were 30 cm and 11 cm long respectively. In the longer magnetron the measurements were made using three radially movable cylindrical Langmuir probes placed at three different axial positions and in the shorter magnetron the axially movable probe was used. From the measurements there were evaluated electron density, electron mean energy, plasma potential and floating potential. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Inter-Electrode Distance and Breakdown Voltage in Low Pressure Argon Discharges
Contributions to Plasma Physics, 2012
This work deals with the Paschen law in electrical breakdown of gases at pd values around the Paschen minimum. From the Townsend model, it is possible to deduce theoretical forms of the coefficients in Paschen's law, of which our calculated values are in the range of the tabulated values from the literature. These formulae show that the breakdown voltage must be influenced by the inter-electrode distance, while the product pd remains a key parameter. This is confirmed by the Paschen curves measured in an argon discharge for inter-electrode distances varying from 2 to 9 cm.
Plasma characterization in magnetized hollow electrodes system
PROCEEDINGS OF THE III INTERNATIONAL CONFERENCE ON ADVANCED TECHNOLOGIES IN MATERIALS SCIENCE, MECHANICAL AND AUTOMATION ENGINEERING: MIP: Engineering-III – 2021
In this paper, investigated the effects of working pressure and magnetic field on the characteristics of plasma produced by DC discharge in Argon gas by using optical emission spectroscopy (OES). The electron number density was measured using the broadening of Stark and the temperature of electron by Boltzmann plot. It was noted that the electron number density () and plasma frequency () increased with increasing gas pressure, especially with applied of magnetic field, i.e. the plasma is more stable with the presence of magnetic field. While the electron temperature () and Debye length () decreases with increasing gas pressure.