Electron accelerator

 

(57) Abstract:

The invention relates to accelerator technology and radiation technology, and more particularly to equipment intended for radiation modification of organic materials, and can be used for creating the technological lines for the production of radiation-modified polymer films. Electron accelerator contains a source of electrons, an accelerating system, vacuum chamber, two foil window for the output beam of electrons from the vacuum chamber, placed parallel to each other in one plane, and the deflection system and the sweep of the electron beam with blocks of magnets and generators frequency electrical signals. The distance between the nearest edges of the Windows along the direction of movement of irradiated electrons of the polymer film is not less than 0.1 m electron Accelerator may also contain frequency-phase detector and the Converter control signal. Patented electron accelerator can improve the physico-mechanical properties of polymer films during their radiation treatment due to more efficient use of the energy of the irradiating electrons and increase coricelli technique and radiation technology, and more specifically to equipment used for radiation modification of organic materials, and can be used for creating the technological lines for the production of radiation-modified polymer films.

Currently known electron accelerators designed for the irradiation of polymer films in the implementation process radiation modification of organic material film.

For example, a known electron accelerator that is used to remove residual monomer from the polymer films by electron irradiation (DE, N 3602865, class B 29 C 71/04, 1987). In a known accelerator for output electron beam of low energy (accelerating voltage of 150 to 300 kV) used single wide foil window for the electrons.

There are also processes of radiation modification of materials, requiring the simultaneous use of two beams of accelerated electrons. For this purpose any two electron accelerator (SU, N 727087, CL H 05 H 5/00, 1983), or one electron accelerator, equipped with two foil Windows for output electron beams, pulsed electromagnet to reject electrons between Volovyk analog of the claimed device is an electron accelerator, contains a source of electrons, an accelerating system, vacuum chamber, two foil window for the output of the electron beam, placed parallel to each other in one plane, and the deflection system and the sweep of the electron beam with blocks of magnets and generators frequency electrical signals (US, N 3679930, CL H 01 J 29/76, 1972).

Using a known accelerator eliminated overheating design lead foil window due to the alternating sweep of the electron beam in a two-outlet boxes. However, using the known two-stage accelerator for irradiation of a moving polymer film, it is impossible to ensure specified for the technological process of production of the polymer film speed continuous move (up to 10 m/min), because the distance between the outlet Windows of the accelerator is not chosen from the condition of providing a certain interval of time between stages of irradiation of the film and of the conditions attaching adjacent foil Windows on the minimum distance that reduce calorific output node of the electron beam.

When applying the known accelerator for the implementation of the two-stage irradiation process, which allows the effect of the e reduces the productivity of the production process of the polymer film as a whole.

The basis of the invention is consisting in the implementation with a high performance two-stage process of irradiation by electrons moving polymer film applied to improve the physical-mechanical properties of polymer films during their radiation treatment due to more efficient use of the energy of the irradiating electrons.

This technical result is achieved by the fact that the electron accelerator containing a source of electrons, an accelerating system, vacuum chamber, two foil window for the output beam of electrons from the vacuum chamber, placed parallel to each other in one plane, and the deflection system and the sweep of the electron beam with blocks of magnets and generators frequency electrical signals, according to the invention the distance between the nearest edges of the Windows along the direction of movement of irradiated electrons of the polymer film is not less than 0.1 m

For a more complete filling of the foil Windows electron beam electron accelerator can contain frequency-phase detector and the Converter control signal, and the inputs of the frequency-phase detector connected respectively with the generator of the m inverter control signal, the output of which is connected to the input of at least one of the specified frequency generators.

In Fig.1 shows a General diagram of the electron accelerator (arrow V indicates the direction of movement of irradiated electrons of the polymer film), and Fig.2 is a cross sectional view of the vacuum chamber of the electron accelerator with views of the irradiated polymer film; Fig.3 shows a functional diagram of the power supply of the electron accelerator of Fig.4 - scheme of the space of States of the molecular structure of polyethylene in primary electron irradiation (the carbon atoms are represented by points) of Fig.5 - scheme of the space of States of the molecular structure of polyethylene in 1 MS after the start of irradiation (the carbon atoms are represented by points) of Fig.6 - scheme of the space of States of the molecular structure of polyethylene after 500 MS after the beginning of irradiation (the carbon atoms are represented by points) of Fig.7 is a graphical temporal changes of free energy F(t) of the polymer system (in relative units) from the exposure dose D(t) (GSR), dialed a polyethylene film with single-stage irradiation; Fig.8 is a graphical temporal changes of free energy F(t) of the polymer system (vlechenii.

Patented electron accelerator refers to the type of direct action accelerators and includes (see Fig.1, 2 and 3) electron source 1 and the accelerating system 2 installed in the chamber 3 filled with gas to increase the electric strength of vacuum chamber 4, in which the deflection of the electron beam, two foil window 5 for the output of the electron beam from the vacuum chamber 4, placed parallel to each other in one plane, the deflection system and the sweep of the electron beam with the blocks of the electromagnets 6 and generators 7, 8 and 9 of the frequencies of electrical signals, frequency-phase detector 10 and the inverter 11 of the control signal.

Foil window 5 for the output of the electron beam serving to separate the vacuum part of the accelerator from the atmosphere, are made of thin titanium foil and placed over the surface irradiated by electrons 12 of the polymer film 13 (see Fig.2). The size of each window is 1000 mm mm Distance between the nearest (inner) edges of the foil window 5 along the direction of movement of irradiated electrons 12 of the polymer film 13 is 250 mm

Blocks of electromagnets 6 has a circular shape, forming part of the system deviation and resortsThe accelerating tube, and on the other with the vacuum part of the output node of the electron beam.

The generator 7 electrical signal transverse sweep of the electron beam (along the X axis, see Fig.2), the generator 8 electric signal longitudinal scan of the electron beam (in the direction along the Y-axis, see Fig.2) and the generator 9 electrical signal periodic deflection of the beam (between the Windows 5) connected to respective blocks of the electromagnets 6.

The inputs of the frequency-phase detector 10 are connected respectively to the generators 7 and 8 of the frequencies of electrical signals transverse and longitudinal scan of the electron beam. The output of the frequency-phase detector 10 is connected to the input of the inverter 11 of the control signal, the output of which is connected to the input of at least one of the frequency generators, namely the input of the generator 8 a longitudinal scan of the electron beam.

Accelerating system 2 is an accelerator tube (see Fig.3) with an equipotential ring 14 connected to a rectifier device 15 through a resistance voltage divider 16, which provides a uniform potential distribution along the length of the accelerating tube.

Gene is Nala are part of the equipment management accelerator, which is connected with the block 17 measuring the total current of the rectifier to measure the beam current and the voltage divider 18 for measurement of accelerating voltage (see Fig.3).

Does the electron accelerator as follows.

Electrons, enitirely the cathode of the electron source 1 (in other terminology, the injector of electrons) are accelerated in the accelerating system 2 by application of a potential difference of 400 to 600 kV to equipotential rings 14. The electron beam generated in the accelerating system, enters the vacuum chamber 4, which is surrounded by blocks of electromagnets 6, which scan the beam in two mutually perpendicular directions X and Y.

The power to the electromagnets 6 is powered by two generators 7 and 8 of the sawtooth current generator 9 rectangular bipolar pulses. In order of frequency f1and f2generators 7 and 8 were located in a predetermined ratio (f1/f2- irrational number) determining random values phase of the sawtooth line scan of the electron beam on the foil boxes 5, which is necessary for a more complete filling of the Windows of the beam, the signals from the outputs of the generators are served in the frequency-phase detector 10. At the output of the detector ry enters the Converter 11 of the control signal. The converted signal is then modulatory input of the generator 8 to adjust a given frequency ratio f1and f2.

After the sweep of the electron beam in one of the foil window 5, the beam is deflected by changing the polarity of the pulse produced by the generator 9, the second foil window 5, which similarly is the scan of the electron beam. The frequency of the longitudinal scanning of the electron beam in the Y-direction is chosen equal to 300 Hz, and the frequency of the transverse scan in the X-direction is 3 kHz. Frequency deviation (shift) of the electron beam between the Windows is changed in the range from 25 to 50 Hz.

Irradiation of polymer films when the electron accelerator is as follows.

The irradiated polymer film 13 is moved with velocity V in a given direction X with a drive of any known construction. The minimum value of the velocity of the film is determined based on the set conditions of the technological process of production of the polymer film and is approximately 10 m/min.

The plot of the film 13 under the first direction of movement of the foil window, oudestraat to set the dose, the value of which is sufficient for the transition of a polymeric material film of free molecular state in the partially cross-linked condition characterized by the formation of three-dimensional molecular structures with higher molecular weight. The length of the originally irradiated area of the film 13, respectively V1.

After moving film 13 to the second foil window 5 is repeated exposure (second stage radiation) beam of accelerated electrons 12 on each initially irradiated area of the polymer film during the time2to set full set dose irradiation. The length of the exposed section of the film is V2(for this example1=2).

The time interval t between the first end and the beginning of the second stage of irradiation shall not be less than 500 m/s, which is necessary to ensure two-stage processing of the polymer film defining the improvement of physico-mechanical properties of polymeric material.

The specified time interval corresponds at a given process speed of the polymer film (Vmin= 10 m/min) the minimum distance between the foil Windows is 0.25 m). Thus, when moving polymer film at a given speed between the two foil Windows 5 electron accelerator is automatically performed two-stage irradiation of polymeric material film, thereby increasing the efficiency of the technological process radiation modification of polymer films.

In the specific example embodiment of the invention in radiation modification of polyethylene film dose dialed the plot of the film in the first stage of irradiation is selected in the range from 20 to 30 kGy.

As the polymer material from which the film is exposed to radiation modification, can be used a wide class slivaushiesia polymer systems such as polyolefins, polyacrylates, and other linear molecular slivaushiesia structures.

Patentable invention is based on the following experimental and theoretical premises.

Studies of structural changes and the properties of the irradiated polymer films, for example polyethylene allowed us to identify distinct stages through which the polymer with increasing dose.

At the initial stage of irradiation, etc is inany molecules and the creation of three-dimensional polymers with higher molecular weight. Purchased this stage the properties of the polymer are determined not so much emerging hard links, forming a branched molecular system as intermolecular interactions between these systems, allowing their mutual displacements and deformations under external mechanical influences. In such conditions, the polyethylene in its properties becomes close to koutsokoumnis materials.

With further increase of the dose density of cross-linking increases and the structure of polyethylene is transformed into a uniform spatial grid. Due to this, the material acquires a new and useful properties : increases the modulus of elasticity, increases the tensile strength, there is resistance to chemical and thermal influences.

At the third stage, starting around 300 kGy and above, the polyethylene begins to turn into a solid glassy material that are not of interest for the modification process of the films.

The presence of these stages in the recruitment process dose gives grounds to consider the kinetics of the emerging transformations in the individual stages. The polymeric material can be represented as a complex system, costeau structure of matter. It is instantaneous electro-chemical subsystem accepts input energy irradiation and instantly modified in accordance with the dialed dose by spatial redistribution of electronic communications and inertial nuclear subsystem perceives these changes and adapts them with significant delay.

In simplified form, the response of the polymer system is a consequence of the following two processes.

The offset of carbon atoms (see Fig.4), between which arose cross connection, to the new equilibrium parameters corresponding to the minimum energy in the field of localization of these bound States. The characteristic relaxation time of this process practically does not depend on the accumulated dose, weakly depends on the structure of the material and is approximately 1 MS.

The configuration change of the molecular chains (see Fig.5) associated with the minimization of energy in total conformational space. This process is initiated after the process of local displacements of carbon atoms and includes part of the structural reorganization of the system, which is caused by the formation and release outside of the matrix-free products of radiolysis, such as molecular the pout stage of irradiation, when the polymer system is not stitched completely and represents the structure of the movable branched polymer molecules (see Fig.5).

Analysis of experimental data for slivaushiesia polymeric materials shows that the restructuring of the system associated with the effect of conformational adjustment, lasts, depending on the external conditions (temperature, mechanical loads, and so on) from 500 MS to 2 C.

Thus, the minimum time from the start of irradiation of the polymer film before the end of the conformational adjustment of the polymer system is 500 MS.

With further increase of irradiation dose, before the formation of fully cross-linked structure of the polymer material (see Fig.6), the processes associated with conformational adjustment, practically does not occur, and emerging cross connection fix and strengthen the previously formed structure.

When the one-stage irradiation of the polymer film full dose D0typed much faster than is necessary to achieve the optimal system configuration with minimum free energy f

For example, when one-stage irradiation of polyethylene film, dizusas is pozicii full dose D0will be 300 MS. During this time, when the selected value of current of the electron beam is typed specified dose of film - 50 kGy (see Fig.7, curve 1).

The irradiation process can be intensified by increasing the current of the electron beam, for example, three times. In this case, a given dose (50 kGy) will be called for 100 MS (see Fig.7, curve 2). In the above example (see Fig. 7) one-step film irradiation dose (Dmol) 20 kGy corresponds to the junction of polyethylene from free molecular state in the cross-linked condition characterized by the formation of three-dimensional molecular structures with higher molecular weight. After dialing the specified dose (respectively after 120 MS for curve 1 and 30 MS for curve 2, see Fig.7) the process of relaxation free energy F stops and polyethylene sewn in the spatial structure of the residual free energy F, which is greater, the more intense was the process of irradiation (see Fig.7 curve 1 according to F(t) corresponds to curve 1 according to D(t), and curve 2 F(t) - curve 2 D(t).

When carrying out work patentable electron accelerator is used more adapted to the internal kinetics of p is taking ends with the formation of a branched molecular structure (see Fig.5) when the dose dial for time 1. The dose of Dmoldialed each section of the film in the first stage of irradiation, pick up enough to go polymeric material film of free molecular state in the partially cross-linked condition characterized by the formation of three-dimensional molecular structures with higher molecular weight. In this example, the dose of Dmolequal to 20 kGy.

After a time interval t after the end of the first stage), necessary for relaxation free energy F of the system when the first dose Dmolthat is the second stage of irradiation during the time2to set the total dose D0sufficient to complete the crosslinking of the polymer structure in a uniform spatial grid.

When the electron accelerator used to implement the two-stage irradiation, must be implemented the following conditions, ensuring optimal use of energy irradiation to obtain the specified properties of the polymer film:

< / BR>
where P0- dose irradiation (Gy/s).

From the presented graphical dependence (see Fig.8) view F and stitched into a more optimal spatial configuration. This phenomenon provides overall improved efficiency of use of energy of the irradiating electrons and the improvement of physical and mechanical properties of the irradiated polymer film.

Thus, by placing foil window of the accelerator on the moving film at a distance L Vt = 0.1 m from each other, it is possible to undertake a two-stage irradiation of the film after a preset time interval t 500 MS , which provides a higher output radiation modification of polymer films, improving the efficiency of use of energy of the electron beam and the improvement of physical and mechanical properties of polymeric material.

Patented electron accelerator is intended for use in radiation technology and can be used for radiation modification of organic materials, in particular polymer films.

The invention can be used to create high-performance processing lines for the production of radiation modified polymer films.

As the exposed film can be applied to a wide class slivaushiesia polymeric materials such as polyolefins, polyacrylates, and other ones, accelerating system, vacuum chamber, two foil window for the output beam of electrons from the vacuum chamber, placed parallel to each other in one plane, and the deflection system and the sweep of the electron beam with blocks of magnets and generators frequency electrical signals, characterized in that the distance between the nearest edges of the Windows along the direction of movement of irradiated electrons of the polymer film is not less than 0.1 m

2. The accelerator under item 1, characterized in that it contains a frequency-phase detector and the Converter control signal, and the inputs of the frequency-phase detector connected respectively to the generators of frequencies of the electrical signals of the longitudinal and transverse sweep of the electron beam, and its output to the input of the inverter control signal, the output of which is connected to the input of at least one of the specified frequency generators.

 

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