Prospects for X-Ray. Amplification with Charge-. Displacement Self-Channeling

Wt develop an analytic theory of charce-displacement self-channeling: a mechanism that can dynamically.trap a short intense pulse ofilight. We focus our attention on the case of most interest for ‘ X-ray amplification: the strongly saturated channel, for which all free electron are expelled from the channel core and’ the channel walls are overdense. Some curious results are: 1) the intensity at the channel walls is independent of the total laser power, 2) the radius of the channel increases.very slowly with laser power, asymptotically as the fourth root, and 3) the power in the channel wall is a constant. The channel is energetically stable in the sense that a bifurcation will cause a net Increase in the electrostatic potential energy, but is only marginally stable against relativistic filamentation in the walls. We also And that th channel is an effective waveguide for all secondary radiation. Scaling studies show a substantial advantage exists by using the highest frequency driving laser available. Since very large energy-deposition rates from mulitiphoton coupling are expected, the channel is Ideal for generating coherent short-wavelength radiation, perhaps well into the X-ray range. © 1989 IEEE