Possible production of cold plasmas through optical-field-induced ionization

Abstract

A one-dimensional model incorporating Maxwell's equations and tunneling ionization is used to predict the plasma temperature after the passage of an intense femtosecond laser pulse through an atmospheric-density noble gas. These calculations are of relevance to a new class of proposed recombination x-ray lasers that use optical-field-induced ionization to generate an initially cold plasma. The residual plasma temperature is determined under a range of relevant conditions, and is found to be minimized for short laser pulses, short wavelengths, and the lowest intensity consistent with reaching the desired ionization stage. Even under optimum conditions, the predicted temperature is significantly greater than that required for high efficiency in the transient-gain regime.