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ESASE is a recent proposal by A. Zholents to significantly enhance the electron peak current for an x-ray SASE FEL. An optical laser interacting with the electron beam in an upstream wiggler induces energy modulation, which is then converted to a large density modulation prior to entering the SASE undulator. The uniformly-spaced, high-current spikes within the electron bunch amplify the SASE radiation much faster than the rest of the bunch, allowing for a shorter saturation length or a larger beam emittance for the same undulator distance. In addition, the use of the optical laser provides natural synchronization for pump-probe experiments and x-ray pulse length control. In this talk, I will describe the ESASE scheme, its possible application to the LCLS, and accelerator physics issues related to the high electron peak current. I will also discuss a related bunch diagnostics technique to obtain the optical replica of the ultra-fast electron bunches in the LCLS.