Hard x-ray generation by low energy, tightly focused laser pulses.

The interaction of λ² laser pulses with plasma is studied to scale the high-field physics from high power laser systems to low-energy, high-repetition-rate lasers. For this purpose, 20 mJ, 40 fs Ti:sapphire laser pulses were focused in a spot of 2.2×2.3 μm² with a maximum intensity of I∼10¹⁹ W/cm². Efficient generations of energetic electrons (∼1 MeV) and hard x-rays with energies of over 100 keV were obtained by irradiating the low-energy, tightly focused laser pulses on a massive Cu target. [ABSTRACT FROM AUTHOR]