High-order harmonic generation in plasma with ultraintense laser and ion beams

► We propose new scheme of HHG in plasma by intense laser and ion beams. ► Impeding factor of relativistic magnetic drift of a strong wave is fully eliminated. ► Copropagating ultraintense laser and ion beams of the same velocities are necessary. ► HHG with significant rates up to MeV photons energies is expected to be realized.