Generation of controlled radiation sources in the atmosphere using a dual femtosecond /nanosecond laser pulse

The generation of powerful radiation sources at predetermined remote locations in the atmosphere using dual femtosecond/nanosecond laser pulses is proposed. The plasma channel generated in the wake of the collapsed beam formed during intense ultrashort pulse propagation in the atmosphere serves as seed target plasma to absorb energy delivered by a long pulse laser, inducing further ionization and significantly enhancing the energy density locally deposited in the plasma. Energy equipartition on time scales shorter than 1 μs results in large energy density in the heated air and is followed by several orders of magnitude enhancement of the radiation emitted by the plasma channel. The effect is demonstrated using a one-dimensional computational study. A proof-of-principle experiment is suggested.