Novel Multiple-Gigahertz Electron Beams for Advanced X-Ray and Gamma-Ray Light Sources
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Current and future generations of advanced light sources largely depend on high brightness electron beams. LLNL has spent the past decade developing Mono-Energetic Gamma-ray (MEGa-ray) sources by scattering laser light off an electron beam for nuclear physics applications. At the SLAC National Accelerator Laboratory, the Linac Coherent Light Source (LCLS) is generating extraordinarily high peak brightness x-ray beams useful for biological, chemical, and physics studies by passing a 13.6 GeV electron beam through a series of magnetic undulators to form a Free-Electron Laser (FEL). Los Alamos is in the process developing the “MaRIE” (Matter-Radiation Interactions in Extremes) concept, which will also rely on FELs. All these light sources would benefit from improved average brightness by increasing the repetition rate of the electron beam source. Since the undulators are based on permanent magnets, they will generate x-rays from as many electron bunches as can be delivered. Similarly, for MEGa-ray sources very little laser light is scattered from each individual electron bunch. If there are additional electron bunches to see the laser, they will also scatter photons, generating more gamma-rays. Modeling has shown that using trains of hundreds of electron bunches allows high gamma-ray fluxes to be generated using ns-long scattering laser pulses. This means that chirped pulse amplification would not be needed for the interaction laser, considerably simplifying the architecture. This would also allow for lower laser bandwidth at the interaction point, along with a larger focal spot size, eliminating the laser contribution to the scattered gamma-ray bandwidth. Additionally, lower charge per bunch allows more flexibility in the transport, simplifying efforts to mitigate noise-inducing dark current. The overarching goal of the proposed research is to develop and demonstrate the required technology to generate multi-GHz rep-rate electron beams at pC-scale bunch charges to allow 100x increases in the average beam current. To achieve this, the project consisted of two major efforts: 1. Demonstration of a photocathode drive laser capable of generating the electron beam. 2. Commissioning of an x-band accelerator to enable studies of inter-bunch electromagnetic field interactions. Excellent results were achieved in both areas.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC52-07NA27344
- OSTI ID:
- 1178389
- Report Number(s):
- LLNL-TR-663490
- Country of Publication:
- United States
- Language:
- English
Similar Records
R&D for a Soft X-Ray Free Electron Laser Facility
Focusing Hard X-rays at Current and Future Light Sources for Microscopy and High-Power Applications