Abstract

Optical-field-induced ionization (OFI) by ultrashort, high-intensity lasers has the potential for realizing high-repetition-rate, table-top x-rays lasers. Recent experiment using a preformed plasma as the initial medium has lead to much progress on this approach.¹ The results suggested that preionization of the medium prior to the OFI would play important roles for creating extremely cold electrons.² The estimated electron temperature produced by this method was much lower than that obtained by OFI without the preformed plasma. In this presentation, we discuss a two-component plasma model by which we can explain the production of an extremely cold plasma. We also present experimental investigation of self-defocusing of the pump beam, which limits the maximum gain length.

© 1995 IEEE