High Duty Cycle Inverse Free Electron Laser

The Inverse Free Electron Laser IFEL) is a laser accelerator, where an electron and laser beam interact inside a strongly tapered magnetic undulator. IFEL enables strong energy exchange between electron and laser beams over extended lengths ~ 1 m), which makes the IFEL an ideal technology for GeV-class electron beam sources, and drivers of compact soft X-ray free electron lasers, and gamma-ray Compton sources. However, the IFEL repetition rate is limited by a maximum attainable repetition rate of the state-of-the-art TW lasers, generally not sufficient for many practical applications. In response to this problem, it is proposed herein to develop and demonstrate, for the first time, IFEL operation in a bunch train recirculated mode, where the entire IFEL system is placed within an active CO2 laser cavity, operating at 40 MHz pulse train mode. Such intracavity IFEL can become a viable technological advance, comparable in cost and characteristics to conventional linear accelerators, but much more compact and versatile. In Phase I, the recirculated IFEL will be designed and the reamplification active cavity will be assembled and tested. The main objectives of the Phase I project are experimental validation of the IFEL active cavity concept, and generation of the detailed design for the Phase II prototype system development.

The strategic goal behind this project is to increase IFEL repetition rate to match the performance of the conventional linear accelerators. If that is accomplished, an order of magnitude more compact, and eventually less expensive, IFEL technology has the potential to disrupt the way GeV-class electron accelerators are designed and built. The immediate applications include compact X-ray FEL light sources, and gamma ray sources.