• D.F. Ratner
  Stanford University, Stanford, California
• A. Chao, Z. Huang
  SLAC, Menlo Park, California

We propose a single-stage scheme to produce coherent soft X-ray radiation directly from a UV seed laser. Seeding an electron bunch prior to compression simultaneously shortens the laser wavelength and increases the modulation amplitude. The final X-ray wavelength is tunable by controlling the compression factor with the RF phase. Photocathode beams with large energy spreads require corresponding large modulation amplitudes, leading to strong over-bunching during compression in the first chicane. We introduce a second chicane to unwind and restore the bunching. We also show that transportation of fine compressed modulation structure is feasible due to recompression in the second chicane.