Appearance and Motion of Vacuum Arc in Variable Frequency Aviation Power Supply System

Variable frequency (360-800 Hz) power technology is widely used in aircraft power supply systems. This paper studies the appearance and motion of vacuum plasmas in axial magnetic field (AMF) and butt contacts at 360-800 Hz. By the influence of the AMF, electrons will travel in a cylindrical spiral, which is advantageous for maintaining arc diffusion. The experimental results show that when the contact separation was 3 mm, the vacuum arcs were uniformly distributed and diffused in the AMF contacts. We found that the maximum magnetic pinch force in an arc column was about 104 Pa in AMF; however, in butt contacts, the arc was intense and was clearly constricted to the same current grade. The magnetic pinch force in the center reached 5 x 10(5) Pa at the minimum radius of the arc column, which formed a higher-pressure gradient that caused the plasma and metal vapor to flow to the lower pressure region and form a plasma jet.