Abstract: When the magnetic filter duct is biased positively 30～60 V relative to the cathode of the MEVVA plasma source, a cathodic vacuum arc discharge is generated between the duct and the cathode. With this modified vacuum arc deposition apparatus, the effects of the filter duct magnetic field on the cathodic arc discharge and the plasma transport are studied. It is shown that the scale of the arc discharge between the filter duct and the cathode decreases, and the efficiency of the plasma transport increases with increasing filtering magnetic filed. The duct magnetic field has no effect on the arc discharge between the anode and cathode of the MEVVA plasma source.