Pulsed power microwave calorimeter

The calorimeter for detection of pulsed power microwave radiation (from several ns to 1 s duration) is developed. The operation of the calorimeter is based on absorption of microwaves by polar fluid with its further expansion into capillary tube and measurement of fluid level in capillary by variable-capacitance transducer. Absorbing surface area of the calorimeter is 1300 cm² (36 × 36 cm). The energy measurements are ranged from several mJ to ∼ 100 J (minimum registrated energy density Qs is ∼ 3 µJ/cm²). The calorimeter absorbs from 90 % to 99 % of falling microwave power with wavelengths 7.5 – 12 cm and 2.3 – 3.7 cm. The measurement error for absorbed energy is less then 5 % for energy Q > 20 mJ.