Delivering High Power: The Role of the Cable
In the last post I wrote about the importance of the waveform in delivering high average power from pulsed power supplies to industrial Dual Magnetron Sputtering (DMS) systems. Low inductance output cabling is preferred to fully access the performance potential of these pulsed power supplies. Preferred cable styles include tri-axial, twisted pair and other low inductance designs. However, there is one in particular that has been effective in the field. It is a four conductor cable, with two opposing conductors connected to one magnetron, and the other two conductors connected to the other magnetron. A cross section of this configuration is shown in the figure below. Litz wire is the best conductor choice for high currents. An alternative is to use a number of coaxial cables in parallel. This approach is scalable to very high currents and very low inductances and has the added advantage that appropriate coaxial cable is typically available off the shelf from multiple vendors. Advanced Energy’s Ascent DMS accessory for pulsed DMS can be mounted next to the coating chamber, separate from the DC power supply that feeds it. In that case, long and expensive AC cables may not be necessary. So, the preferred approach that gives best power delivery results can be an installation in which DC supplies are installed in the rack and the accessory (Ascent DMS) is mounted on or near the chamber itself, therefore shortening the AC cables significantly and minimizing the cable parasitic parameters.
Quadrupole output cable configuration.