Longitudinal magnetic field effect on the electrical breakdown in low pressure gases

Abstract

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.

The role of magnetic energy on plasma localization during the glow discharge under reduced pressure

“…These phenomena illustrate in a principled way contribution of the magnetic fi eld energy at the expense of the electric fi eld energy input in the course of the glow discharge. The element of novelty of our work is not in itself to demonstrate the contribution of the magnetic fi eld energy in supporting the glow discharge because the literature in this area provides suffi cient information [3][4][5], but to demonstrate his role as a factor for localization of plasma at the electrically grounded element of vacuum apparatus and, in addition, giving it the status of the electrical cathode, which can undergo phenomena characteristic to magnetron sputtering. The presented results are the preliminary results showing a phenomenon that we believe is of great importance for one of the plasma surface engineering method, the magnetron sputtering method, due to the opportunity of simplifying the construction of the magnetron as a source of vapors.…”

“…It is known that glow discharge enhanced by the magnetic fi eld applied just above the surface of the cathode infl uences the breakdown voltage decreasing its value, both the magnetic fi eld oriented parallel with respect to the electric fi eld [3], as in the case of their perpendicular orientation [4,5]. The magnetic fi eld was used to increase the effi ciency of a glow discharge in the gas under reduced pressure in the construction of one of the most important sources of plasma among the plasma surface engineering methods -the magnetron sputtering.…”

Two-dimensional modeling of the electrical breakdown in rare gases

“…The secondary mechanism of emission, which can in this case take place with cathode, has a "kinetic and potential" origin. The output of the majority of materials being about 4 eV, the kinetic energy gained by the ions in the discharge plasma 04003-p. 2 can be sufficient to extract the secondary electrons from cathode [16][17]. Several empirical expressions of the emission coefficient by cathode ionic bombardment (the number of electrons emitted by incidental ions) are given in the literature [18][19] 0.032 0.78 2…”

“…The most significant question in the plasma industrial applications is the optimization of the energy consumption, which is related to the breakdown voltage [2]. However, the gas breakdown process has assumed new importance in particularly for further development these devices.…”

Experimental study on the effect of longitudinal magnetic field on Townsend discharge characteristics in low pressure argon gas

“…The electrical breakdown is presented by Petraconi et al (2004) at low-pressure of argon and nitrogen gases under the influence of an external longitudinal magnetic field. Plane-parallel aluminum electrodes is used at various spacing (4cm < d < 11cm) with a dc voltage (0<V< 1 kV).…”