DC vacuum arc in a nonuniform axisymmetric magnetic field

An experimental investigation is performed of the characteristics of DC vacuum arc during the opening of contacts in an axisymmetric magnetic field with different ratios between the axial and radial components of magnetic field induction. A study is made of the main features of the dynamics of plasma glow in the contact gap during the stable and unstable stages of arcing until the arc extinction in the current range of $50$ to $150$ A with the voltage limited at the instant of breaking of current to a level of $8$ kV. Possible mechanisms of disturbance of the vacuum arc stability in an axisymmetric magnetic field are discussed.