Abstract

Recent experimental and theoretical findings concerning (1) the multiphoton production of X-rays from clusters^1,2 and (2) high intensity modes of stable channeled propagation in underdense plasmas^3,4 indicate a new method for establishing conditions necessary for amplification in the multikilovolt range. The ability to apply power densities controllably at or above vigorous thermonuclear levels (>10¹⁹ W/cm³) in materials is the basic issue for achieving efficient amplification of X-rays. These two new nonlinear phenomena are being united to produce and control the imperative power compression; the multiphoton mechanism serves to establish the conditions locally while the confined propagation provides the required spatial organization. The present work, which experimentally demonstrates the first combined expression of these two complex nonlinear processes through direct X-ray imaging of Xe(M) emission (~1 keV) in stable self-trapped channels, (1) reveals the exceptional compatibility of their mutual scaling for realizing the necessary power density, (2) provides confirming evidence for the action of a superstrong coherent multi-electron intense-field interaction in the X-ray generation from the Xe clusters, and (3) furnishes new detailed information on the dynamics of the radial intensity distributions associated with the channeled propagation. The resulting knowledge of the scaling relations underlying these phenomena enables the optimum conditions for amplification to be specified up to a quantum energy of ~5 keV. Recent experimental studies indicate the simultaneous creation of multiple inner-shell vacancies in Xe(L) and Xe(M) shells with the retention of several electrons in relatively weakly bound outer orbitals. The formation of these "Swiss cheese" ions can create favorable conditions for X-ray generation and amplification in the multikilovolt range.

© 1995 IEEE