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Abstract

The invention concerns a device for creating an electron curtain (5). The device consists of a cylindrical chamber (1) in which has been accommodated an elongated, electron-emitting filament (2) and a shell (3) encircling the filament so that the filament is located in an elongated depression (6) formed by the shell. Furthermore, the device comprises members (7) for accelerating the electrons and a window (4) in the wall of the chamber (1), through which the electron curtain can be directed to the outside of the device. The shell (3) encircling the filament (2) has on both margins of the depression (6) been shaped into an accelerating electrode (7) which can be brought to a negative potential with reference to the wall of the chamber (1), and the depression constitutes a diffusion volume for the electrons emitted from the filament and in the region of which there are mouldable parts, such as the accelerating electrodes (7) or the additional electrodes (9) on the bottom of the depression, by the aid of which the admission of electrons into the accelerating electric field and thereby the intensity of the electron curtain (5) that is produced are adjustable. Owing to the diffusion of electrons, it is possible with the means to produce an electron curtain with uniform intensity, and by suitably shaping the parts (7,9), the intensity distribution of the curtain may be adjusted in desired manner.

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First Claim