Plasma lens yields bright gamma-rays exceeding 10^28 peak brilliance
Physicists modeled a fast pinching burst mechanism in submillimeter plasma that converts over 20% of electron beam energy into gamma-rays.
Physicists from Zhejiang University and Shanghai Jiao Tong University have modeled a mechanism called the beam fast pinching radiation burst to generate ultra-bright gamma-rays, according to a study published in Research doi.org
Researchdoi.orgOpen source ↗. The concept uses a giga-electron volt electron beam injected into a 400-micrometer plasma with an upramp density profile. The process enables rapid transverse beam compression, yielding collimated gamma-ray bursts with peak brilliance exceeding 10^28 photons s^-1 mm^-2 mrad^-2 per 0.1% bandwidth and photon energies spanning from mega-electron volts to giga-electron volts.
Beam pinching dynamics
In the proposed setup, the upramp plasma profile acts as an effective plasma lens for a 5-GeV, nanocoulomb-class electron beam. As the beam travels through the increasing plasma density, the transverse focusing force intensifies, pinching the electron beam to a sub-micrometer diameter of roughly 0.2 micrometers. This contraction increases electron density by hundreds of times. The focused dense beam drives nonlinear plasma wakefields up to tens of teravolts per meter, propelling the interaction into a radiation-dominated regime where the quantum parameter exceeds 0.2.
High conversion efficiency
Under these conditions, strong-field radiation reactions cause the intense emission of high-energy photons with a cutoff energy above 2 GeV. The simulated energy conversion efficiency from the electron beam to gamma radiation reaches 31% in a typical case and up to 46.3% with optimized beam parameters, compared to approximately 0.3% observed in uniform plasma schemes. The resulting radiation burst exhibits a 0.2-micrometer spot size, a divergence of about 3 milliradians, a pulse duration of around 5 femtoseconds, and approximately 1.8×10^10 photons at 1 MeV.
The authors noted that the mechanism remains robust against initial beam imperfections, tolerating energy spreads up to 10% and lower beam charges down to hundreds of picocoulombs doi.org
Researchdoi.orgOpen source ↗. The necessary upramp density profiles can be fabricated using laser prepulse heating of solid films or supersonic gas jets with blades, enabling implementation on modern laser-plasma or radiofrequency accelerator platforms.
