  The SNS linac accelerates an average beam current of 2 mA to an energy of 968
MeV. The linac is pulsed at 60 Hz with an H- beam pulse of 1 ms. The first 185
Mev of the linac uses normal conducting cavities, and the remaining length of
the linac uses superconducting cavities. The linac operates at 402.5 MHz up to
87 MeV and then changes to 805 MHz for the remainder. This paper gives an
overview of the Linac RF system. The overview includes a description and
configuration of the high power RF components, the HV converter/modulator, and
the RF controls. Issues and tradeoffs in the RF system will be discussed,
especially with regards to the use of pulsed superconducting cavities.
