Effects of Exposure Time and Extracted Interval on Observation of Motion and Splitting Behavior of Cathode Spots for Vacuum Arc Deposition

The proper control of cathode spot motion is the key issue in the application of vacuum arc deposition (VAD). Improving the arc spot discharge requires considering the structure and properties of the deposited films/coatings as well as the deposition velocity, target utilization, etc. To achieve this goal, it is necessary to precisely observe cathode spots during discharge at both microscopic and macroscopic scales. However, how to capture the motion and splitting behavior of cathode spots using simple equipment remains an open question. In this work, we analyze the motion and the splitting behavior of cathode spots considering industry application on a Cr target for VAD under arc currents in the direct mode (70 A, 100 A, 150 A 200 A) and 400 A as a peak value in the pulse mode with two applied magnetic fields (20 Gs and 40 Gs) at the macroscopic scale using a high-speed digital camera, employing different exposure times under an extracted interval of 1 ms ranging from 0.01 ms to 20 ms. Furthermore, the images are also compared when the interval is extended to 2 ms and 4 ms. Considering all factors in the available data, 0.05 ms is suggested as the best exposure time, and 1 ms is suggested as the most suitable extracted interval for cathode spot observation under these conditions. Hopefully, this paper provides a suitable technique for observing the motion and splitting behavior of cathode spots at a macroscopic scale with the purpose of suppressing/eliminating the injection of macroparticles at the source for industrial VAD coating products of high quality.