An offset model radiation calorimeter

An offset model calorimeter specially designed for FEL experiments on EPA-74 is presented. The calorimeter is substantially capable of deducting the temperature drift because it consists of two hollow thin wall cone graphite absorbers and two thermistors. The device is capable of measuring the microwave radiated energy, microwave waveform and radiated frequency simultaneously. We have measured a 20 mJ of microwave radiated energy, 1MW of radiated power and 33 GHz of radiated frequency in FEL experiments on EPA-74 without a guide magnetic field by using the calorimeter.