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Approximate each source as localized, keep the angular factors unchanged and use inverse-square flux dilution. The increased distance givesThis carries the composition/thickness convention of the previous answer. A greater source distance reduces fractional distance and angle variation across a given substrate, improving composition uniformity at the cost of rate. A real magnetron sputtering target is extended, with an angular emission distribution, and gas scattering can change the distance law; this is an estimate rather than a calibrated prediction.

Assume that each target's incorporated flux is proportional to its applied power over this operating range, and that the same composition convention is used throughout. The calibration gives $F_A/F_B=0.35/0.65$ at equal powers. Holding the A target unchanged while making the two incorporated fluxes equal therefore requiresThe B power decreases because B originally supplies more material. This linear magnetron sputtering approximation neglects power-dependent yield, target condition, resputtering and changes in sticking probability. A second composition measurement is the experimental check.