Abstract: The generation of excessive electron radiation is prevented in an apparatus which comprises an accelerator means for generating and accelerating electrons. The accelerator comprises an electron injector for emitting injector pulses, an electron gun for receiving the injector pulses, a waveguide receiving electrons from the electron gun and a high frequency source for supplying RF signals for the generation of an electric field for accelerating the electrons in the waveguide and generating the electron beam which has a predetermined intensity level according to the amplitudes of the injector pulses. A sensing means senses the amplitudes of the injector pulses and generates sensing signals. The amplitudes of the sensing signals are compared with predetermined reference voltage values and the generation of the electron beam is prevented if the amplitudes of the sensing signals exceed the predetermined reference voltage value.

Abstract: The generation of excessive electron radiation or X-ray radiation is prevented in an apparatus which comprises an accelerator means for generating and accelerating electrons. These electrons form an electron beam which has a predetermined low intensity level for the generation of electron radiation or a predetermined high intensity level for the generation of X-ray radiation. In case of generating electron radiation a scattering foil or a target, respectively are arranged in the trajectory of the electron beam. The foil and the target are movably arranged on a support means.