[摘要]:The properties of high-energy runaway electrons generated during a nanosecond discharge in an air filled diode at pressures up to 3 x 10(5) Pa were studied using x-ray absorption spectroscopy. The results of studies of the discharge at different pressures and with different lengths of cathode-anode gap allow an insight into the factors that influence the energy distribution of runaway electrons. Energy distribution functions for runaway electrons produced in particle-in-cell simulation were used to create the x-ray attenuation curves via a computer-assisted technique simulating the generation of x-ray by energetic electrons. The simulated attenuation curves were compared to experimental results. (C) 2012 American Institute of Physics. [doi: 10.1063/1.3675462]