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Battery energy storage technology has a promising future in the field of compact high-power pulse drivers due to its high energy storage density. In this paper, three types of high-performance lithium batteries, such as lithium titanate (LTO) battery, lithium iron phosphate (LFP) battery, and Ni,Co,Al (NCR) ternary lithium-ion battery, have been studied in different ambient temperatures by using DC internal resistance measurement method. The result shows that the ohmic internal resistance of lithium batteries increases when the temperature drops. When the temperature is above -30 °C, the ohmic internal resistances of the three types of battery are nearly identical. At -50 °C, the ohmic internal resistances of LFP battery and LTO battery are about 83 mΩ and 151 mΩ, respectively, and the ohmic internal resistance of NCR li-ion battery increases by one order of magnitude. The energy loss from LTO battery and LFP battery during pulse discharge is similar. In the temperature range of -30 °C to 50 °C, the energy loss of NCR li-ion battery pulse discharge is the largest. At -50 °C, the energy loss of NCR li-ion battery is the least.

The influences of the eigenfrequency and the intrinsic quality factor of a cavity on the phase shift in the relativistic klystron amplifier (RKA) are investigated. An analytical expression is derived to describe the phase of the gap voltage in a cavity. The theoretical and simulation results indicate that the eigenfrequency of the buncher cavity can significantly affect the phase shift of the output microwave in the RKA. In contrast, the influences of the eigenfrequency and the intrinsic quality factor of the output cavity on the phase shift of the RKA are small. The analytical expression can effectively estimate the phase difference among different RKAs resulting from the machining and assemblage inconformity in the experiment. It is suggested that the differences among the eigenfrequencies of the buncher cavities should be managed in 0.1% of the operation frequency to achieve phase locking among different RKAs.Index Terms-Equivalent circuit method, high-frequency characteristics, phase shift, relativistic klystron amplifier (RKA).