The anode magnetron torch (AMT), which is a physically confined magnetron plasma system, was developed for large-scale applications. It was found that a uniform funnel-shaped negative glow is crucial to achieve uniform plasma treatment in the focused area; this can be attained by adjusting the distance between two electrodes. The relationship between the gap distance (the distance from the edge of the glass tube to the cathode surface) and CDST e2 (the cathodic dark space thickness at the edge of the glass tube) is another important factor which affects whether materials removed by sputtering will redeposit on the substrate surface. The CDST shrinks not only with the increase of input power, applied voltage or current, but also with the increase of the magnetic field strength or system pressure. The CDST e1 (the CDST at the center of the focused area) will contract and the CDST e2 will expand with a decrease in the gap distance. The influence of the electrode distance on the CDST is complicated, because it causes not only a change in magnetic field strength, but also a change in the distribution of the magnetic field strength near the cathode surface.