Balmer-α soft X-ray amplification in a carbon plasma produced by short-pulse lasers

Soft X-ray amplification is numerically simulated in a recombination plasma which is produced on a solid carbon target irradiated by a 2-psec neodymium-glass laser (λ= 1053 nm) at an intensity of 6×10¹⁵ W/cm². The results demonstrate that for a dense plasma in a strong electromagnetic field, the formation of a highly-ionized plasma is considerably accelerated by optical-field-induced ionization from excited states of atomic ions. Predicted gain coefficients for Balmer-a X-ray amplification in hydrogenic ions is in reasonable agreement with recent observations.