Limiting values of superhard X radiation yield under electron slowing down

Radiation, originating by high-current electron beam bremsstrahlung in foils made of materials with high atomic number (C,Al,Ti,Fe,Cu,Ta,W,Pb) is considered. It is theoretically proved, that superhard X-radiation yield in bremsstrahlung spectrum from targets of optimal thickness tends with increasing electron energy to limited value of ΔEsm energy, characteristic of each target material. ΔEsm for light targets in this case is significantly higher as compared to traditionally applied heavy targets, but it is achieved by higher energies