Both the Raman, coherent Compton, and Compton regimes of high-gain ion-ripple Lasers (IRL’s) are studied. The IRL works by coupling a negative-energy beam wave (or ponderomotive potential) to an electromagnetic wave by means of the ion ripple (backward Raman scattering or backward coherent Compton scattering) or by amplification of an em wave by negative Landau damping (backward Compton scattering). By employing fluid theory, the dispersion relation for wave coupling is derived and used to calculate the radiation frequency and linear growth rate. The nonlinear saturation mechanism is explored. A multidimensional (one dimension in space, three dimensions in momenta and fields) particle-in-cell simulation code was developed to verify the ideas, scaling laws, and nonlinear mechanisms. The effect of momentum spread is also studied; there is a slow decrease in the growth rate and efficiency as well as broadening of the radiation spectrum. This scheme may provide tunable sources of coherent high-power radiation. By proper choice of device parameters, sources of microwaves, optical, and perhaps even x rays can be made. An ion ripple in a plasma can provide a very short undulator wavelength (e.g., ∼${10}^{\mathrm{-}2}$ cm) and strong dc electric fields (e.g., ∼${10}^{10}$ V/m; equivalent to a magnetic field of 30 T). The plasma also produces an ion channel that provides guiding of electron and laser beams. The IRL’s may generate high-power (e.g., >1 MW), coherent, short-wavelength photons with relatively low beam energy (e.g., ∼10 MeV) and possibly low beam quality requirement. The availability of tunable sources for wide wavelength regimes, coherence and high power, as well as lower cost and simplicity of equipment are emphasized.

• Received 21 October 1991

DOI:https://doi.org/10.1103/PhysRevA.45.4077