Seminars Archive

The Echo-Enabled Harmonic Generation (EEHG) R&D Program at SLAC

Abstract
The EEHG seeding approach provides a path to generation of high harmonics from a seed laser. At SLAC, we are simulating the performance of various external seeding approaches, including EEHG and HGHG, for the LCLS-II and we are pursuing an experimental demonstration of the EEHG approach, the Echo-75 experiment, which is installed at the SLAC NLCTA test accelerator. The NLCTA is a 60 MeV X-band rf gun driven linac. To enable the Echo-75 experiment, we installed an additional X-band accelerator structure and rf power system (X2) to boost the beam energy from 60 MeV to 120 MeV, two undulators where the beam would interact with lasers to modulate the beam energy, three chicanes, and additional diagnostics to characterize the performance including 8 new OTR screens, two X-band transverse deflecting cavities and an additional undulator used as a radiator. The 1st chicane allows one laser to be brought onto the beamline, the two following chicanes provide the dispersive paths necessary to rotate the longitudinal phase space. The Echo beamline has been used to generate the 15th harmonic of the seed laser and compare the resulting harmonic against that generated with HGHG and against simulations. At present, we are installing an additional undulator with plans to generate the >30th harmonic.