RF-Free Chirp Removal Using Longitudinal Wakefields

After final bunch-compression in a typical linac-based free electron laser (FEL), a residual chirp remains on the beam, which must be removed for adequate FEL operations. Typical mitigation techniques require the inefficient off-crest use of hundreds of meters of acceleration cavities. This inefficiency increases the upfront and operational costs of future x-ray FELs, which have demonstrated groundbreaking applications in bio- imaging, material science and other forefront sciences. Investigation and commercialization of the use of corrugated structures to produce longitudinal wakefields that passively dechirp x-ray FEL quality beams without any RF is proposed. A complete system, with tunable structures and diagnostics, will be made available as a single customizable unit. Commercial Applications and Other Benefits: This project is an enabling technology for compact soft x-ray FELs while also decreasing costs of presently planned hard X-ray FEL facilities. The cost savings to National Laboratories is in the tens of millions of dollars, allowing a more manageable construction and operation cost for FEL facilities. In addition, the technology developed here has a direct spin-off application as a beam-based THz generator, which fulfills a need in biological and security imaging applications.