High-efficiency fast pinching radiation of electron beams in nonuniform plasma

The continuous development of bright x/gamma-ray sources has opened up new frontiers of science and advanced applications. Currently, there is still a lack of efficient approaches to produce gamma-rays with photon energies up to GeV and with high peak brilliance comparable to modern free-electron lasers. Here we report a novel mechanism called beam fast pinching radiation burst to generate such gamma-ray sources. It is achieved by injecting a GeV electron beam into a submillimeter plasma with an upramp density profile, enabling violent beam pinching to occur rapidly. During this process, a burst of collimated gamma-rays is efficiently produced with photon energy up to GeV, energy conversion efficiency exceeding $30\%$, and peak brilliance exceeding $10^{28}$ photons s$^{-1}$ mm$^{-2}$ mrad$^{-2}$ per $0.1\%$ bandwidth. All of these are several orders of magnitude higher than existing gamma-ray sources. This opens a novel avenue for the development of extremely bright gamma-ray sources for both fundamental research and cutting-edge applications.