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The SRF cavities used for LCLS-SC are 1.038m long and made of nitrogen-doped niobium. Each cavity contains nine cells. Strings of eight cavities are bolted together with a button design BPM and a multifunction magnet inside a cryomodule.
RF Source
The 1.3 GHz CW RF is produced by the low level RF (LLRF) system then amplified by a solid state amplifier (SSA). Each cavity has its own SSA. The RF generated by the SSA is directed into the tunnel through rectangular waveguides and fed into the downstream end of the cavity through a fundamental power coupler (FPC) .
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