Study on the retrograde motion of arc under transverse magnetic field

The phenomena of retrograde motion of arc in the atmosphere under transverse magnetic field were studied. AgSnO₂ contacts were set in DC resistive and inductive circuits, respectively. The break voltage was 28 V, the current ranged from 1 to 5 A, and the magnetic flux density changed from O to 100mT. A high speed camera and an oscilloscope were used to record time variations of arc images, voltages and currents, simultaneously. Different from previous experiment results, the arc motion showed three stages which was more obvious under larger magnetic flux density in inductive circuit. It was also found that the arc movement was closely related with the arc voltage. Explanation to the retrograde motion under such conditions was given.