RF loss in and leakage through thin metal film

|Traditional RF enclosures are formed by metal bulk material, in which the eld decays exponentially over a skin depth = p 2=! 0. With typical bulk dimension at least one order of magnitude higher than , the eld outside the metal enclosure is then negligible. The surface resistance Rs presented to the RF eld is 1= . This article presents analysis of an RF shield formed by thin metal lm. We nd that a metal thickness r of the order of skin depth, can provide an excellent RF shielding due to re ection at the interface. The surface RF loss can be reduced with proper choice of metal thickness, and heating can be reduced. The thin metal lm also facilitates cooling on the back of the lm via thermal conduction. For a very thin coating, the surface RF loss is inversely proportional to thickness, while inductance is proportional to thickness, and thus it is possible to customize the accelerator beam impedance through careful choice of coating thickness. Keywords|Thin metal lm, RF leakage, impedance.