Expanding Characteristics of Vacuum Arc Plasma in Radial and Axial Direction

Expanding characteristics of the plasma generated from pulse vacuum arcs of lead and copper cathode were investigated using a time of flight method and the Langmuir probe method. The measurements were made for the plasma expanding in the radial direction and expanding in the axial direction through the anode meshes. The time dependent charge state distributions and the direct velocities were determined from the TOF measurement. It appeared that singly and doubly charged ions are generated for lead cathode and singly to triply charged ions are generated for copper cathode, independent of the direction. The plasma density in axial direction is higher than in radial direction for the same arc current and the directed velocity of the ions in axial direction is faster than in radial direction