Observation of a Hot High-Current Electron Beam from a Self-Modulated Laser Wakefield Accelerator

A highly relativistic electron beam produced by a 50 TW laser-plasma accelerator has been characterized by photonuclear techniques. The beam has large divergence that increases with plasma density. The electron yield also increases with plasma density and reaches up to $4\times {10}^{11}$ electrons ( $>10\mathrm{}\mathrm{MeV}$), with beam current approaching the Alfvén limit. Effective electron temperatures exceeding 8 MeV are found, leading to an order of magnitude higher photonuclear activation yield than in solid target experiments with the same laser system.