[en] Specific features of proton and H^- ion linear accelerators for energies of some hyndreds MeV and with the total mean current of units, tens and hundreds mA are considered. With regard to these accelerators the problems of ensurign high radiation purity and an increase in efficiency being of utmost importance. To limit the losses in the main part of the accelerator to 10^-4 - 10^-6 (radiation-pure accelerator) the filtration of the longitudinal and transversal emittances of the beam is shown to be necessary; some versions of filters are considered. Special attention is paid to the H^- ion losses due to their charge exchange on the residual gas. It is shown that the present day technology makes it possible to design a proton and H^- ion linear accelerator with a total efficiency of about 60 per cent and beam currents 150-200 mA