Device scan of the electron beam

 

(57) Abstract:

Usage: in Electrophysics, units of radiation processing of products and materials using accelerated electron beams. The essence of the invention: device scan of the electron beam contains vakuumirovaniya the bell with the exit window foil, the deflecting magnet generator sweep and corrective magnet, which is made in the form of two blocks located at the wide end of the funnel with two sides of him. Each block contains two permanent magnet, made in the form of bars of variable cross-section, extending from the middle to the end of the block, and the magnetic core having the shape of the bar. Permanent magnets have a direction of magnetization perpendicular to the wide side of the socket, and the magnets of one unit have opposite directions of magnetization, and the magnets are located in different units against each other, have the same direction of magnetization. The use of the device resulting in reduced energy consumption, increased reliability and stability of operation of the device scan. 3 Il.

The invention relates to Electrophysics, specifically to the field of acceleration, transport, and transformation beams charger, side buttons is accelerated electron beams, in particular, units of radiation sterilization of medical products.

In existing installations, radiation sterilization, the beam of accelerated electrons emerging from the electrostatic or high-frequency accelerator is deployed in the plane using the device scanner beam. The irradiated objects are moving on the conveyor in the direction perpendicular to the plane of sweep of the beam. The beam penetrates the irradiated object and creates in its entirety radiation dose sufficient for sterilization of products at the selected speed of the conveyor (see Svinyin M. P. the Calculation and design of high-voltage electron accelerators for radiation technologies. M. Energoatomizdat, 1989).

The device scanner in such plants contains vakuumirovaniya socket extending in the plane of sweep of the beam. The narrow end of the funnel is attached to the accelerator. On the wide end of the funnel is the output window made of thin metal foil, through which the electron beam exits the vacuum to the atmosphere. On the narrow end of the funnel has an electromagnet, powered from the generator base. The electromagnet creates in the cavity of the socket variable in time the magician, rejected them on an angle, which depends on time and, thus, the fan-shaped beam is deployed in the plane.

In some cases it is necessary to obtain a good uniformity of the irradiation object. In particular, in the sterilization of medical products unevenness of exposure should not exceed 20% To obtain good uniformity of the depth of the box with sterilized products must be parallel to the electron beam. To convert fan-shaped beam in parallel are used corrective magnets. The closest analogue of the proposed device contains a correction magnet in the form of an O-shaped electromagnet, in which the height of the poles and the air gap equal to the corresponding values in the electromagnet scanner. The windings of both coils have the same number of turns and connected in series to the generator base. Due to the equality of the currents of power and size, the electrons are deflected in a correction magnet at the same angle as in the magnet sweep, and their trajectories become parallel to the axis of the accelerator (see Titov, C. A. and other Output device of the electron accelerator. Auth. mon. N 708944, B. I., 1980, No. 39, S. 324).

When solving the problem of the scanner, as well as saving electricity.

These tasks can be solved through the use of permanent magnets. Corrective magnet can be designed in such a way that its magnetic field, in contrast to the specified prototype is constant in time but varies in space. To this end correction magnet is in the form of two blocks located on the wide end of the funnel on both sides of him. Each of the blocks contains two identical bar of magnetically hard material and one piece of soft-magnetic material acting as a magnetic core. Bars of magnetically hard material is magnetized perpendicular to the wide side of the socket, and the direction of magnetization of the two bars one block opposite, but the direction of magnetization of adjacent bars in different blocks are the same. The bars have a variable cross-section is small in the middle and increasing towards the ends of the block. Therefore, the magnetic field between the bars maximum at the ends and is equal to zero in the middle. When the migration of electrons through such a field the trajectory of their change: the farther an electron is from the axis of the accelerator, the greater the angle turns its trajectory. After Strait is Proposed corrective magnet gives power savings because the permanent magnets do not require power. Due to the lack of electronic power supplies and coils increases the reliability of the scan beam. The magnetic field of permanent magnets is more stable over time and in relation to external influences (temperature and others) than the parameters of electronic power supplies.

In Fig. 1 shows the proposed device, front view; Fig. 2 is a side view, and Fig. 3 is the same, top view.

The device comprises a socket 1, the output window 2, the deflecting electromagnet 3, the sweep generator 4, the blocks corrective magnet 5, each of which contains two permanent magnet 6 and the magnetic core 7.

The socket 1 has a shape extending in the plane of sweep of the beam and constant in the perpendicular plane. The funnel with the narrow end attached to the electron accelerator 8 and forms with it a single vacuum volume. On the wide end of the funnel installed sealing output window 2 made of thin foil. The socket is made of a nonmagnetic material such as stainless steel. On the narrow end of the funnel is installed deflection electromagnet 3 so that its poles are from different sides of the socket. The General 6, made in the form of elongated bars of variable cross-section, and the magnetic core 7 made in the form of an elongated bar of soft-magnetic material (e.g. iron Armko). Tile permanent magnets attached to the magnetic core without air gaps. Height of bars (along the Central line of the accelerator and socket) is not changed, and the thickness of each permanent magnet minimum in the middle of a block and increases toward the end. Permanent magnets are made of magnetized magnetic solid material, such as Ba-ferrite. The direction of magnetization perpendicular to the wide side of the bell. Two permanent magnet of one unit have opposite directions of magnetization, and the permanent magnets of different blocks that are located against each other, have the same direction of magnetization. The direction of magnetization of permanent magnets conventionally shown in Fig. 3 arrows. Corrective magnet may be positioned so that the magnetic field produced between the blocks, either in the vacuum cavity of the socket, or in the air after the output open 2.

The device operates as follows.

The deflecting electromagnet, powered from generacy and time varying in accordance with the sawtooth law. The electron beam emerging from the accelerator 8, passes through a magnetic field deflecting electromagnet and rejected them in the plane of sweep of the beam, and the deflection angle is proportional to the magnitude of the magnetic field at the time of passage of the beam. The result for the period changes in the magnetic field at the exit of the funnel produces a beam of electrons, an unfolded fan. The trajectory of some of the electrons are shown in Fig. 1 dash-dotted lines. Corrective magnet creates in the output area of the bell or after the magnetic field that is directed perpendicular to the direction of motion of the electrons. Magnetic induction of this field is equal to zero in the middle and increases towards the ends of the magnet, and the field direction at the ends of the corrective magnet opposite. This field modifies the trajectory of the electrons so that they become parallel to the center line of the socket. As a result the entire amount of the irradiated object 9 moving on the conveyor perpendicular to the plane of sweep of the beam, is irradiated uniformly.

Changing the beam section can be smooth, in which case they are wedges, as shown in Fig. 3. Thus forming a wedge (the dividing line between constant the population of the magnetic field. Changes in the beam section can also be stepped. In this case, each block may be made in the form of a set of plates adjacent one another. The design of the bars is determined in each case by considerations of manufacturability and cost of manufacture.

An example implementation can serve as a device scan of the electron beam with energy of 5 MeV. Scan angle is 65othe dimensions of the irradiated object HH mm. Corrective magnet has a length of 450 mm and a height of 60 mm Each permanent magnet is made of ferrite 2,BE in the shape of a bar with a stepwise increase of the thickness, it consists of 8 plates with thicknesses from 1.8 to 12 mm According to calculations performed using three-dimensional computer programs, magnetic induction at the ends of the correcting magnet is 1500 Gauss, and the nonlinearity of the distribution of the induction along the length adjustment of the magnet does not exceed 5% of the Estimated non-uniform irradiation of the object does not exceed 10%

Device scan of the electron beam, containing vakuumirovaniya socket with the output window, the deflecting magnet, generator, scanner and corrective magnet, characterized in that the adjusting magnet is made in the form of two nl the material of variable cross-section, small in the middle of the block and increasing toward its ends, magnetized perpendicular to the wide wall of the funnel, and the direction of magnetization of the two bars one block opposite, and the direction of magnetization of the bars located in different units against each other, the same.

 

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