Why double door coater coating when two gate voltage difference is very big

Why double door coater coating when two gate voltage difference is very big

Should be a magnetron sputtering, but don't know whether I reaction sputtering, if is reactive sputtering, low voltage film slow is normal. Have not seen a similar coating machine, don't know whether two cavity is same? If not, there may be a flat place, but the speed is fast enough, show that the pressure is no problem. In addition, the stand or fall of magnet tests only target on the surface of the magnetic field strength is good, the higher the magnetic field intensity, the lower the voltage. Power supply is intermediate frequency or dc or rf, twin target, if not need to pay attention to whether the power cord connect anti? Made no mention of target's own reason, may be in the air oxidation, surface to sputter, with fine gauze after polishing time target practice.
In addition, the target water not too cold. When exposed to atmosphere are easy to be surrounded by water. Swap of vacuum coating machine equipment suggested that the two target location, so you can find out the cause of the target and magnet or coating chamber.