We report on the design and development of a strongly HOM damped copper RF cavity for the NLC damping rings. The cavity is based on the sucessful PEP-II RF cavity but incorporates many simplifications and improvements. The cavity is designed for a frequency of 714 MHz, gap voltage of 500 kV and beam current of 800 mA. We present the RF design and HOM impedance calculations done in MAFIA, the RF, thermal and stress analyses performed in ANSYS and the simplified mechanical design and assembly process. Designs for the RF window, HOM loads and tuners are described. Options for increasing the stored energy or further lowering the HOM impedance are discussed. This design could easily be scaled up or down in frequency and could be useful for other projects such as new light sources.

This paper discusses the design, fabrication and testing of a high power alumina disk window in WR1500 waveguide at L Band, suitable for use in the NLC damping ring RF cavities at 714 MHz and the LEDA Accelerator at 700 MHz. The design is based on the fabrication methods used for the successful PEP-II cavity windows. Four prototype windows at 700 MHz have been produced by LBNL for testing at LANL. The RF design and simulation using MAFIA, laboratory cold test measurements, fabrication methods and preliminary high power test results are discussed.