Increase in the yield of X-ray photons upon two-pulse laser excitation of a solid target in air

A scheme is proposed for efficient generation of hard X-rays upon two-pulse excitation of a solid target in air by nanosecond and femtosecond laser pulses. The yield of hard X-rays upon two-pulse excitation increases by a factor of ~17 compared to that upon single-pulse femtosecond excitation. The optimal delay time between pulses was 10 μs.