Betatron x-ray sources from laser-plasma interaction are characterized by compactness, ultrashort duration, broadband spectrum and micron source size. However, high-quality measurements with good statistics, especially in a single shot, require fluxes and energies beyond the current capabilities. Here, we propose a method to enhance the flux and brightness of the betatron sources without increasing the laser energy. By irradiating an edge of a microtape target with a femtosecond laser, a strong surface plasma wave (SPW) is excited at the edge and travels along the lateral plasma-vacuum interfaces. Tens of nC of electrons are peeled off and accelerated to superponderomotive energies by the longitudinal field of the SPW, whilst undergoing transverse betatron oscillations, leading to emission of hard x-rays. Via three-dimensional particle-in-cell simulations, we demonstrate that a tabletop
100 TW class femtosecond laser can produce an ultrabright hard x-ray pulse with flux up to 10⁷ photons eV⁻¹ and brilliance about 10²³ photons s⁻¹ mm⁻² mrad⁻² 0.1%BW⁻¹, paving the way for single-shot x-ray measurements in ultrafast science and high-energy-density physics [1].

[1] Xiaofei Shen, Alexander Pukhov, and Bin Qiao High-flux bright x-ray source from femtosecond laser-irradiated microtapes Comm. Physics, accepted (2024)
 

Betatron radiation,relativistic plasmas,peeler regime