Each target material and coating process has limitations as to how fast the material can be deposited from each magnetron.
Thus each different process has a limited dynamic deposition rate (DDR).These limits for most materials have been experimentally obtained and are correlated with the power density that was applied to the target at the time of the deposition.
Using this information we create a unit for calculation the normalized dynamic deposition rate (nDDR) that has the units of (nm-m/min)/(kw/m).This unit can be used along with the maximum power density that target vendors recommend using with their targets to figure out approximately what the dynamic deposition rate of each rotary magnetron will be for a particular process.
Desired (or maximum) power density = Power applied from power supply in kW divided by the target tube length in meters -> (kW/m)
nDDR(nm-m/min)/(kW/m) * Desired power density(kW/m) = DDR
DDR / substrate velocity = coating Thickness per magnetron
Number of cathodes required = Target coating thickness / Coating thickness per magnetron