Аннотация:The results of calculation and optimization of pulsed linear accelerator with magnetic mirror on the beam energy, adjustable in the range of 20 - 45 MeV, designed for explosives detection and other applications are presented. The accelerator consists of an electron gun with an off-axis placed cathode with a beam hole on axis; of about 1.6 m long section of standing wave bi-periodic accelerating structure, operating at 2856 MHz, which is optimized to achieve the capture coefficient of more than 50% and of the energy spectrum width of about 2%; of a movable dispersion free magnetic mirror made with rare earth permanent magnet material. Accelerator provides acceleration of the beam with a pulse current of 100 mA to an energy of 45 MeV with RF power consumption less than 10 MW.