Influence of an axial magnetic field on the electron temperature in a vacuum arc plasma

Abstract

The influence of an axial magnetic field on the electron temperature of a vacuum arc plasma was studied experimentally and theoretically for moderate discharge currents of 400-600 A, magnetic flux densities of 0-50 mT, and various cathode materials such as uranium, titanium, and carbon. Experiments were performed using the vacuum arc ion source (VARIS) and the electron energy spectra were measured with a 127 electrostatic cylinder spectrometer. The electron temperature in the inter-electrode gap of a vacuum arc was calculated from an energy balance equation that was supplemented by an magnethydrodynamic approach of the plasma flow. The plasma flow is constricted by an external axial magnetic field instead of the free spherical plasma flow in its absence, leading to an increase in the electron temperature. The influence of different input parameters such as the magnetic flux density, arc current, the ion to arc current ratio, the initial plasma jet radius, and the distance from the cathode on the electron temperature was studied and compared with the experimental results.Index Terms-Axial magnetic field, electron energy distribution, electron temperature, vacuum arcs.

Sheet Plasma Excitation by a 2.45 GHz Microwave Power Introduced through a Local Gas Injection Type Dielectric Window

“…The effect of increasing the magnetic flux density can be clearly observed by the general increase in T e , n e (except 0.5 kW) and V Plasma while V F becomes more negative. The increase in T e for higher magnetic flux density agrees with the findings in [1] and [3] who attribute the effect to Joule heating arising from the decrease in plasma current cross section leading to increase in energy yield per unit volume of plasma.…”

“…Effects due to change in magnetic field intensity to sustain plasmas have been discussed by several researchers [1][2][3][4][5][6]. Krinberg [1] observed the limit whereby the effect of the applied magnetic field can be used to reduce the size of the plasma column, increase the electron temperature and the average ion charge.…”

The Influence of a Longitudinal Magnetic Fields on a Non‐Uniform Positive Column

“…In addition, in order to maintain the present discharge current, the electric field in the positive column at higher magnetic fields rises; then the electron temperature increases due to this grow in axial electric field, as in Fig. 2 [23]. However, the charged particles are more confined in the cathode vicinity, at probe 1, as the magnetic field is raised, as can be observed from Fig.…”

Vacuum Circuit Breaker Postarc Current Modelling Based on the Theory of Langmuir Probes

“…The quantities T e , m i , and n i (0) (the initial ion density) cannot be measured with our measuring equipment, and their value has to be estimated or taken from the literature. T e is normally in the order of 2-10 eV [24]- [27], and we assume that only copper ions are present inside the gap, so m i = 1.06 • 10 −25 kg. We assume further that the ion density decays exponentially (n i = n i (0) exp(−t/τ )).…”