Theory of Kα emission efficiency under the irradiation of ultra short pulse laser

When laser light hits thin solid foil, one can obtain soft X-rays, and this is sometimes called a laser plasma X-ray source. When the peak power of the laser becomes extremely high by shortening the pulse duration, it is also possible to observe hard X-ray spectra including Kα and Kβ emission. A team at Sandia National Laboratory has recently reported some calculations on the efficiency of Kα emission. The conversion efficiency of laser energy into Kα X-ray energy is clearly a critical parameter for designing an X-ray source. Basically the value is fairly small, but the team's simulations indicate that an enhancement of efficiency greater than tenfold over conventional single targets may be possible by introducing a two-phase target concept. For more information, see the paper, "Efficiency Enhancement for Kα X-Ray Yields from Laser-Driven Relativistic Electrons in Solids", A. B. Sefkow et al., Phys. Rev. Lett. 106, 235002 (2011).