Experiments were conducted with the aim of keeping low-current DC vacuum arcs stable. A permanent columnar magnet was embedded in the anode and a permanent disk-shaped magnet was arranged behind the anode. As result, the arc plasma is strongly constricted to a column and a light emitting point appeared on the anode surface. Generation of the anode spot was confirmed by detecting anode metal vapor and ions using mass and spectroscopic analyses under low-current arcs of less than 20 A. 

Effects of a magnetic field on the characteristics of a low-current DC vacuum arc plasma of less than 30 A were examined by arranging the electrodes in a straight line or perpendicularly. Two types of magnetic fields were applied to the gap by embedding a small column magnet inside the electrode and arranging a disc magnet at the back side of the electrode. The arc plasma forms a column depending on the magnetic field distribution and an anode spot is generated under strong magnetic field on the anode side. Spectroscopic analysis of emissions from cathode and anode showed that the cathode metal ions arrive at the anode and the anode metal ions arrive at the cathode along the magnetic field, but neutrals are not guided by the magnetic field and only a small part of the neutrals arrive at the opposite electrode in the perpendicular arrangement. 