Enso-gutzeit Oy

Pertti Sikanen

Pertti Puumalainen

Rauno Rantanen

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.

Means for creating an electron curtain

The invention concerns a procedure and a means for creating an electron curtain (5) intended to be used in irradiating a surface (8) and adjustable as to its intensity distribution. The electron curtain is elicited by producing with an elongated filament (2) placed in a chamber (1), free electrons in a space (6) surrounding the filament, by accelerating the electrons by means of an electrode structure (3) confining the space and by directing the electron curtain formed by the accelerated electrons out from the chamber through a window (4) permeable to electrons in its wall. It is a substantial novelty in the invention that regulation of the intensity distribution of the electron curtain (5) takes place by use of an elongated body (9) of magnetically soft material and of a row of magnets constituted by magnets (10) placed side by side, one of the two being disposed substantially parallelling the filament (2) behind the filament as seen from the direction of the window (4) of the chamber (1) and the other being disposed outside the window of the chamber before the electron curtain, the basis for the regulation achievable with the magnets being the absorption, dependent on the strength of the magnetic field, of electrons in the electrode structure (3). The magnets (10) being functionally independent of each other, the intensity of the electron curtain can be adjusted to be uniform or to vary as desired at different points of the curtain.

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Kuopio, Finland

Pertti Sikanen