JP4808879B2 - Electron accelerator and method for accelerating electrons - Google Patents

Abstract

An electron accelerator includes a vacuum chamber having an electron beam exit window. The exit window is formed of metallic foil bonded in metal to metal contact with the vacuum chamber to provide a gas tight seal therebetween. The exit window is less than about 12.5 microns thick. The vacuum chamber is hermetically sealed to preserve a permanent self-sustained vacuum therein. An electron generator is positioned within the vacuum chamber for generating electrons. A housing surrounds the electron generator. The housing has an electron permeable region formed in the housing between the electron generator and the exit window for allowing electrons to accelerate from the electron generator out the exit window in an electron beam when a voltage potential is applied between the housing and the exit window.

Description

[0001]
BACKGROUND OF THE INVENTION
Electron beams are used in many industrial processes, such as drying and curing inks, paints and paints. In addition to sterilizing liquids, gases and surfaces, electron beams are used to clean hazardous waste.
[0002]
A conventional industrial electron beam apparatus includes an electron beam accelerator that irradiates an electron beam onto a material to be processed. The accelerator has a large vacuum chamber surrounded by lead and contains an electron generating filament or a filament powered from a filament power source. During operation, the vacuum chamber is continuously evacuated by a vacuum pump. The filament is surrounded by a housing, which has a grid-like opening facing a metal foil electron emission window located on one side of the vacuum chamber. A high voltage is applied between the filament housing and the radiation window by a high voltage power source. The electrons generated from the filament are accelerated, pass through the opening lattice of the housing from the filament as an electron beam, and are emitted to the outside from the radiation window. A power supply for the radiating device is generally provided to planarize the electric field lines in the region between the filament and the radiating window. This prevents the electrons in the electron beam from concentrating at the center of the beam as shown in graph 1 of FIG. 1, and distributes the electrons uniformly over the entire beam width as shown in graph 2 of FIG. .
[0003]
The disadvantage of using electron beam technology in the industrial field is that conventional electron beam equipment is complex and furthermore, maintaining the equipment requires highly trained personnel in vacuum technology and accelerator technology That is. For example, during normal operation, both the filament and the metal foil of the electron beam radiation window need to be replaced periodically. Accelerators are very large and heavy (generally 20-30 inches (508-762 mm) in diameter, 4-6 feet in length (1220-1830 mm), and thousands of pounds in weight) Such maintenance work must be performed on site.
[0004]
Replacing the filament and the electron beam radiation window requires opening the vacuum chamber, which causes contaminants to enter the vacuum chamber. This exchange requires a long downtime. This is because if the filament and the metal foil of the radiation window are exchanged, the accelerator can be operated only after the accelerator is exhausted and adjusted for high voltage operation. This adjustment requires power from a high-voltage power supply, which is gradually applied over time to incinerate contaminants in the vacuum chamber and the surface of the radiant window that enter when the chamber is opened. Raise. This process takes 2 to 10 hours depending on the degree of contamination. If a radiant window leaks along the way, it must be repaired, further extending the time of this process. Finally, every year or every two years, it is necessary to replace the high voltage insulator of the accelerator and disassemble the entire accelerator. This process takes about 2 to 4 days. As a result, when it is necessary to replace the filament, the electron beam radiation window metal foil, and the high voltage insulator, the manufacturing process requiring electron beam radiation will be interrupted for a long time.
[0005]
SUMMARY OF THE INVENTION
The present invention provides a small and simple electron accelerator for an electron beam device, thereby facilitating maintenance work of the electron beam device, and maintenance work by highly trained personnel in vacuum technology and accelerator technology. It is to eliminate the need.
[0006]
In a preferred embodiment of the present invention, an electron accelerator comprising a vacuum chamber having an electron beam emission window is provided. The radiation window is formed from a metal foil joined in metal contact with the vacuum chamber and hermetically seals between the two. The thickness of the radiation window is less than about 12.5 μm. The vacuum chamber is hermetically sealed and maintains a permanent self-holding vacuum inside. The electron generator is placed in a vacuum chamber and generates electrons. A housing surrounds the electron generator. The housing has an electron transmission region formed between the electron generator and the emission window on the wall, and emits electrons from the electron generator when a voltage is applied between the housing and the emission window. It accelerates as an electron beam out of the window.
[0007]
In a preferred embodiment, the series of openings in the housing form an electron transmission region. Preferably, the radiation window is formed of a titanium foil having a thickness of about 8 to 10 μm and is held by a support plate having a series of holes through which electrons can pass. The configuration of the holes in the support plate can be changed, thereby changing the transmission of electrons across the support plate to generate an electron beam with a desired variable density profile. In general, the outer edge of the radiation window is brazed, welded, or joined to a vacuum chamber so as to hermetically seal with the vacuum chamber.
[0008]
Preferably, the vacuum chamber includes an elongated ceramic member. In one preferred embodiment, the elongated ceramic member is corrugated so that high voltages can be used. A ring-shaped spring member is coupled between the radiation window and the corrugated ceramic member to compensate for the difference in expansion coefficient.
[0009]
In another preferred embodiment, the elongated ceramic member has a smooth surface and a metal shell surrounds the ceramic member. The semimic member has a frustoconical hole through which an electrical lead extends to supply power to the electron generator. A flexible or flexible insulating plug surrounds the electrical lead, and the plug has a frustoconical surface that seals against the inner surface of the frustoconical hole. A retaining cap is secured to the shell and retains the plug in the frustoconical hole.
[0010]
The present invention also provides an electron accelerator comprising a vacuum chamber having an electron beam emission window. An electron generator is placed in the vacuum chamber and generates electrons. A housing surrounds the electron generator and has an electron transmission region formed between the electron generator and the emission window in the housing. The electron transmission region accelerates electrons from the electron generator to the outside of the emission window as an electron beam when a voltage is applied between the housing and the emission window. The housing is provided with a passive electric field shaper (shaping means), and makes the electric field lines between the electron generator and the emission window flat to make the electron distribution in the lateral direction of the electron beam uniform.
[0011]
Preferably, the electron transmission region comprises a first series of openings in the housing between the electron generator and the emission window, while passive electrical line shapers (shaping means) oppose each other in the electron generator housing. A second and third series of openings formed in the sides are provided.
[0012]
The present invention provides a small replaceable modular electron beam accelerator. When the filament or electron beam emission window needs to be replaced, the entire accelerator is replaced, which significantly reduces the downtime of the electron beam device. This also does not require skilled personnel in terms of vacuum technology and accelerator technology to maintain the device. Also, there is no need to replace the high voltage insulator on site. Furthermore, the electron beam accelerator of the present invention has fewer components and requires less power than conventional electron beam accelerators, thus realizing low cost, simplicity and high efficiency. Due to the miniaturization of the accelerator, it is suitable for use in devices with limited space, such as small printing presses, or devices for line web sterilization and curing between stations.
[0013]
The foregoing and other objects, features and advantages of the present invention will become apparent from the following detailed description of preferred embodiments of the invention as illustrated in the accompanying drawings. In the drawings, the same reference numeral refers to the same part in the different drawings. The drawings are not necessarily to scale, emphasis being placed on illustrating the principles of the invention.
[0014]
Detailed Description of Preferred Embodiments
2 and 3, the electron beam accelerator 10 is a replaceable modular accelerator and is incorporated in an electron beam device housing (not shown). The accelerator 10 includes an elongated, generally cylindrical, outer shell 14 that is sealed at both ends. The proximal end of the outer shell 14 is closed with a proximal end cap 16 welded to the outer shell. Preferably, the outer shell 14 and end cap 16 are each made of stainless steel, although alternative methods may be made of other suitable metals.
[0015]
The tip of the accelerator is closed with an electron beam radiation window membrane made of titanium foil, which is brazed to the stainless steel tip end cap 20 along the outer edge 23. The end cap 20 is welded to the outer shell 14. The radiation window 24 is generally about 6-12 μm thick, more preferably about 8-10 μm. Alternatively, the radiating window 24 can be made of any other suitable metal foil, such as a suitable non-metallic low density material such as magnesium, aluminum, or ceramic. Furthermore, the radiation window 24 can be welded or joined to the end cap 20. A rectangular support plate 22 having holes or openings 22a through which electrons pass is bolted to the end cap 20 using bolts 22b to help retain the radiating window 24. Support plate 22 is preferably made of copper for heat dissipation, but may alternatively be made of other suitable metals such as stainless steel, aluminum, or titanium. The hole 22 a in the support plate 22 is about 1/8 inch (3.2 mm) in diameter and provides an opening of about 80% so that electrons pass through the emission window 24.
[0016]
The end cap 20 is provided with a cooling passage 27 through which coolant is pumped to cool the end cap 20, the support plate, and the radiation window 24. The coolant enters from an inlet (inlet) 25a and exits from an outlet (outlet) 25b. The inlet 25a and the outlet 25b are connected to the electron beam refrigerant supply port and the return port of the electron beam apparatus housing. The refrigerant supply port and the return port are provided with an “O” ring seal for sealing the inlet 25a and the outlet 25b. The accelerator 10 is about 12 inches (305 mm) in diameter, 20 inches (508 mm) long, and weighs about 50 pounds (23 kg).
[0017]
A high voltage electrical connection receptacle 18 connected to the connector 12 of the high voltage power cable is attached to the proximal end cap 16. A high voltage cable supplies power from the high voltage power supply 48 and the filament power supply 50 of FIG. The high voltage power supply 48 preferably provides approximately 100 kV, but may alternatively be increased or decreased depending on the thickness of the radiating window 24. The filament power supply 50 preferably supplies approximately 15V. The two electrical leads 26a / 26b shown in FIG. 2 extend from the receptacle 18 down to a disk-shaped high voltage ceramic insulator 28 that divides the accelerator 10 into an upper insulating chamber 44 and a lower vacuum chamber 46. It penetrates. To join the ceramic insulator 28 to the outer shell, the insulator 28 is first brazed to a metal intermediate ring 29 having the same expansion coefficient as the insulator 28, such as KOVAR®. Next, the intermediate ring 29 is brazed to the outer shell 14. The upper chamber 44 has SF after exhausting. ₆ It is filled with an insulating medium such as a gas, but may alternatively be filled with oil or a solid insulating medium. Gaseous and liquid insulating media can be filled and discharged through the shut-off valve 42.
[0018]
The electron generator 31 is located in the vacuum chamber 46 and preferably comprises three 8-inch (203 mm) long tungsten filaments 32 (FIG. 4) electrically connected in parallel. Alternatively, two filaments 32 can be used. The electron generator 31 is surrounded by a stainless steel housing 30. The filament housing 30 has a series of lattice-like openings 34 provided on the flat bottom wall 33 and a series of openings 35 provided on the four side walls of the housing 30, and these openings 34, 35 are electron passage regions. Is forming. The filament 32 is preferably disposed in the housing 30 approximately halfway between the bottom wall 33 and the top wall of the housing 30. The opening 35 does not extend substantially above the filament 32.
[0019]
Electrical leads 26a and wires 52 shown in FIG. 3 electrically connect the filament housing 30 to the high voltage power supply 48. Electrical lead 26 b passes through hole 30 a in filament housing 30 and electrically connects filament 32 to filament power supply 50. The radiating window 24 is electrically grounded, causing a high voltage to be applied between the filament housing 30 and the radiating window 24.
[0020]
The vacuum chamber 46 is provided with an inlet (exhaust port) 39 shown in FIG. 2 for exhausting the vacuum chamber 46. The inlet 39 has a stainless steel outer pipe 36 welded to the outer shell 14 and a sealable copper tube 38 brazed to the outer pipe 39. After evacuating the vacuum chamber, the pipe 38 is cold pressed with pressure to form a seal 40 and hermetically seal the vacuum chamber 46.
[0021]
In use, the accelerator 10 is incorporated in the electron beam apparatus and electrically connected to the connector 12. The housing of the electron beam apparatus or the lead enclosure surrounding the accelerator 10 is incorporated. The filament 32 is powered from a filament power supply 50 (AC or DC) and is heated up to about 4200 ° F. to generate free electrons in the filament 32. The high voltage between the filament housing 30 and the emission window 24 applied from the high voltage power supply 48 of FIG. 3 accelerates free electrons 56 on the filament 32 shown in FIG. It radiates outside through the opening 34 of the housing 30 and the radiation window 24 (FIG. 3).
[0022]
The side opening 35 generates a weak electric field around it, and this electric field flattens the high voltage electric field line 54 between the filament 32 and the radiation window 24 with respect to the plane of the bottom wall 33 of the housing 30 (this Parallel to the plane). By flattening the high voltage electric field lines 54, the electrons 56 of the electron beam 58 are relatively straight from the housing 30 through the opening 34 without focusing to a central position as shown in graph 1 of FIG. Radiated. As a result, the electron beam 58 is a broad beam having a profile similar to that of graph 2 of FIG. 1 and having a width of about 2 inches (50.8 mm) and a length of about 8 inches (203 mm). The thin high-density electron beam in the graph 1 of FIG. 1 is not preferable because the hole penetrating the radiation window 24 is burned out.
[0023]
To further illustrate the function of the side opening 35, FIG. 5 shows the housing 30 without the side opening. As can be seen from FIG. 5, in a state where the side opening 35 is omitted, the electric field line 54 is curved upward in an arch shape. Since the electrons 56 travel so as to be substantially orthogonal to the electric field lines 54, the electrons 56 are focused on a thin electron beam 57. In contrast, in FIG. 4, the electric field lines 54 are flat and the electrons 56 travel in the state of a wide, substantially unfocused electron beam 58. Therefore, in the conventional accelerator, it was necessary to flatten the high-voltage field line using the power source of the high-voltage extractor (extractor) and to uniformly distribute the electrons in the lateral direction of the electron beam. In the present invention, by providing the opening 35, the same result can be obtained by a simple and inexpensive method.
[0024]
When replacing the filament 32 or radiation window 24 of FIG. 2, the entire accelerator 10 need only be removed from the electron beam device housing and replaced with a new accelerator 10. Since the new accelerator 10 has been adjusted in advance for high voltage operation, the downtime of the electron beam device is only a few minutes. The operator of the electron beam apparatus does not need to be highly proficient in maintaining vacuum technology or accelerator technology because only a single part needs to be replaced. Furthermore, since the accelerator 10 is small and light, it can be replaced by one person.
[0025]
In order to recondition the old accelerator 10, it is desirable to send the old accelerator to another location, such as a company specializing in vacuum technology. First, the radiation window 24 and the support plate 22 are removed, and the vacuum chamber 46 is opened. Next, the housing 30 is removed from the vacuum chamber 46 and the filament 32 is replaced. If necessary, the insulating medium in the upper chamber 44 is discharged from the valve 42 provided in the outer shell 14. Thereafter, the housing 30 is mounted in the vacuum chamber. The support plate 22 is bolted to the end cap 20 and the radiation window 24 is replaced with a new one. The outer edge 23 of the new radiant window 24 is brazed to the end cap 20 to form a sealing structure. Since the radiation window 24 covers the support plate 22, the bolt 22 b, and the bolt hole, there is no leakage even if there is no “O” ring or the like, and this window 24 has an auxiliary function of sealing the front surface of the support plate 22. Yes. The copper pipe 38 is removed and a new copper pipe is brazed to the pipe 36. These adjustments are performed in a controlled clean air environment to prevent contamination of the vacuum chamber and the radiant window.
[0026]
By assembling the accelerator 10 in a clean environment, the radiation window 24 can easily be 8 to 10 μm thick or 6 μm thick. This is because dust or other contaminants are prevented from being deposited on the radiation window 24 between the radiation window 24 and the support plate 22. Such contaminants pierce the radiation window 24 with a thickness of less than 12.5 μm. In contrast, the electron beam emission window of a conventional accelerator requires a thickness of 12.5 to 15 μm because it is assembled in a dusty field during maintenance work. The thickness of the radiation window of 12.5 to 15 μm is sufficient to prevent dust from piercing the radiation window.
[0027]
Since the radiation window 24 of the present invention is generally thinner than the radiation window of a conventional accelerator, the power required to accelerate electrons to pass through the radiation window 24 is significantly less. For example, in a conventional accelerator, about 150 kV is required to accelerate electrons through a radiation window having a thickness of 12.5 to 15 μm. On the other hand, in the present invention, about 80 to 125 kV is sufficient to penetrate the radiation window having a thickness of 8 to 10 μm.
[0028]
As a result, the accelerator 10 is more efficient than the conventional accelerator to generate an equivalent electron beam. Furthermore, since a lower voltage is sufficient, the accelerator 10 can be made smaller, and a disk-shaped insulator 28 that is smaller than the cylindrical or conical insulator used in the conventional accelerator can be used. The reason that the accelerator 10 can be made smaller than the conventional accelerator is that the components of the accelerator 10 can be assembled closer to each other because the voltage is low. If the inside of the vacuum chamber is controlled to a clean environment, components can be assembled closer together. In addition to operating at high voltages, conventional accelerators are rich in contaminants within the accelerator, and it is necessary to provide spacing between components to prevent arcing between them. In fact, in conventional accelerators, contaminants from the vacuum pump enter the accelerator during use.
[0029]
The vacuum chamber 46 is then evacuated from the inlet 39 and the tube 38 is cold crimped and sealed. When the vacuum chamber 46 is sealed, the vacuum chamber 46 remains permanently in a vacuum and there is no need to activate the vacuum pump. This makes it easy and inexpensive to operate the accelerator 10 of the present invention. Thereafter, the accelerator 10 is preconditioned for high voltage operation. In this adjustment, the accelerator 10 is connected to the electron beam apparatus, and the voltage is gradually increased to incinerate all the contaminants in the vacuum chamber 46 and the radiation window 24. All molecules remaining in the vacuum chamber 46 are ionized by a high voltage and / or electron beam and accelerated toward the housing 30. The ionized molecules collide with the housing 30 and are trapped on the surface of the housing 30, resulting in a further increase in vacuum. The vacuum chamber 46 can also be evacuated while the accelerator 10 is preconditioned for high voltage operation. The accelerator 10 is removed from the electron beam device and stored for reuse.
[0030]
FIG. 6 shows a system including three accelerators 10a, 10b, 10c. These accelerators are arranged in a zigzag manner so as to irradiate the electron beam over the entire width of the moving product 62 without gaps. Irradiate with electron beam 60. Since the electron beams of the accelerators 10a, 10b, and 10c are thinner than the outer diameter of one accelerator, the electron beam 60 cannot be irradiated over the entire width of the product 62 even if the three are arranged side by side. Instead, the accelerator 10b is arranged slightly laterally rearwardly with respect to the accelerators 10a and 10c along the moving direction of the product 62. As a result, the side ends of the respective electron beams 60 are aligned in the lateral direction without gaps. As a result, as shown in the figure, the entire surface of the moving product 62 is irradiated by the electron beam 60 in a stepped manner. Although three accelerators are shown, as an alternative method, four or more accelerators 10 are arranged in a zigzag to irradiate a wider product, or two accelerators 10 are arranged in a zigzag to form a narrow width product. Can also be irradiated.
[0031]
7 and 8 illustrate another preferred method of electrically connecting leads 26a and 26b to filament housing 30 and filament 32. FIG. The lead wire 26 a is fixed to the upper wall of the filament housing 30. Three filament brackets 102 extend downward from the top wall of the filament housing 30. A filament mount 104 is attached to each bracket 102. An insulating block 110 and a filament mount 108 are attached to the wall of the filament housing 30 opposite the filament mount 104. Filament 32 is stretched between filament mounts 104 and 108. . A flexible (flexible) lead wire 106 electrically connects the lead wire 26b and the filament mount 108. Filament bracket 102 has a spring action to compensate for expansion and contraction of filament 32 during use. The cylindrical bracket 112 supports the housing 30 instead of the lead wires 26a / 26b.
[0032]
The filament arrangement 90 shown in FIG. 9 is another preferred method of electrically connecting a plurality of filaments to increase the width of the electron beam beyond that provided by a single filament. The filaments 92 are arranged in parallel and are electrically connected in series with each other by electrical leads 94.
[0033]
The filament arrangement 98 shown in FIG. 10 shows a series of filaments 97 that are arranged in parallel and are electrically connected in parallel by two electrical leads 96. This filament arrangement 98 also has the effect of expanding the width of the electron beam.
[0034]
The accelerator 70 shown in FIG. 11 is another preferred embodiment of the present invention. The accelerator 70 generates an electron beam in the direction of an angle of 90 degrees with respect to the electron beam generated by the accelerator 10 of FIG. In the accelerator 70, unlike the accelerator 10, the filament 78 is not perpendicular to the major axis A of the vacuum chamber 88 but parallel to it. Further, a radiant window 82 is disposed on the outer shell 72 rather than the vacuum chamber end cap 74 and extends parallel to the major axis A. The radiation window 82 is held by a support plate 80 attached to the side wall of the outer shell 72. An elongated filament housing 75 surrounds the filament 78 and has a lattice-like opening 34 that opens in a direction perpendicular to the long axis A on one side wall 76 of the housing 75. The side opening 35 of the filament housing 75 opens in a direction perpendicular to the opening 34. The end cap 74 closes the end face of the vacuum chamber. The accelerator 70 is suitable for irradiating a wide area with an electron beam without using a plurality of zigzag accelerators (FIG. 6), and is suitable for use in a narrow place. The accelerator 70 can be about 3-4 feet long (900-1200 mm) and can be arranged in a zigzag to achieve a wider illumination range.
[0035]
The accelerator 100 shown in FIG. 12 shows still another embodiment of the present invention. Accelerator 100 includes a generally cylindrical outer shell 102 formed of a ceramic material having a vacuum chamber 104 therein. The outer shell 102 has a closed proximal end 106 and an open distal end 118 on the opposite side. The outer surface of the outer shell 102 includes a series of corrugations 102a, which allows the accelerator 100 to operate at a higher voltage than when the outer shell 102 is a smooth surface. The open end 118 has a portion with a smooth outer surface. A metal end cap 110 surrounds and covers the smooth open tip 118 of the outer shell 102 to seal the vacuum chamber 104.
[0036]
An end cap 110 having a radiating window 24 is brazed to an intermediate annular metal spring 108 that is brazed to the outer shell 102. Thus, an annular spring 108 is engaged between the end cap 110, which is a ceramic member, and the radiation window 24, and the spring 108 seals the vacuum chamber 104. The spring 108 allows the ceramic outer shell 102 and the end cap 110 to maintain a hermetic seal therebetween while allowing different rates of expansion and contraction in the radial and axial directions. The spring 108 accomplishes this by spacing the end cap 110 slightly away from the outer shell 102 and further comprising a resilient material. The spring 108 has an annular inner V-shaped ridge 108 a, and its inner leg is brazed to the outer shell 102. An annular outer flange 108 b projects radially outward from the V-shaped raised portion 108 a and is brazed to the end cap 110.
[0037]
The end cap 110 includes an outer annular wall 112 and an inner annular wall 114, forming an annular gap 116 therebetween, into which the open tip 118 of the outer shell 102 enters. The gap 116 is wider than the wall thickness of the tip 118 so that the tip 118 is spaced from the side and bottom surfaces of the gap 116 and a vacuum is applied around the tip 118 as indicated by the gaps 116a, 116b, 116c. A space or passage for connecting the chamber 104 to the inlet 39 is formed. By this passage, the vacuum chamber 104 is exhausted through the inlet 39. The inlet 39 is brazed or welded to the outer annular wall 112 of the end cap 110 and extends through the wall.
[0038]
Further, the end cap 110 includes a support plate 22 having a through hole 22a. The radiant window 24 is joined to the end cap on the support plate 22, generally by heating and pressurizing, or by brazing or welding. A cover plate 120 having a central opening 120a covers and protects the radiation window 24. The end cap 110 has a cooling passage 27 similar to the passage shown in FIG. Although the end cap 110 is shown as a single piece, it may be formed from multiple parts in an alternative manner. For example, the support plate 22 and the annular wall 114 may be separate components. Furthermore, the annular wall 114 can be eliminated if necessary.
[0039]
Filament housing 30 is positioned in vacuum chamber 104 directly below the closed proximal end 106 of outer shell 102. Electrical leads 26a / 26b extend through the proximal end 106 of the outer shell 102 and are sealed thereto. The filament 30 and the electron generator 31 are the same as those shown in FIG. Although an opening 35 is shown in the filament housing 30, an alternative method can eliminate this opening.
[0040]
The accelerator 130 shown in FIG. 13 is still another preferred accelerator. The accelerator 130 includes a metallic outer shell 122 that surrounds a ceramic inner shell 124 having a smooth outer surface. Preferably, the open tip 118 of the inner shell 124 extends to the support plate 22 thereby forming an annular wall (ceramic member) 136 of ceramic material between the vacuum chamber 134 and the outer shell. Alternatively, the tip 118 may be terminated before reaching the support plate 22. Inner shell 124 has a frustoconical opening 124 a that extends through a proximal end 119 opposite the distal end 118. An electrical lead 128 having a connector 138 extends through the frustoconical opening 124a and supplies power to the filament housing 30 and the electron generator 31 via the electrical lead 26a / 26b.
[0041]
The filament housing 30 and electron generator 31 are similar to those of the accelerator 100 (FIG. 12). The electrical lead 128 extends through the central opening 126a of a flexible (flexible) insulating plug 126 made of a polymeric material. The insulating plug 126 includes a mating frustoconical outer surface 126b for sealing the hole 124a in close contact with the frustoconical hole 124a. A retaining cap 140 secured to the outer shell 122 applies an axial compressive force to the plug 126, pressing the plug 126 against the converging surface of the frustoconical hole 124 a and pressing the plug 126 against the outer periphery of the electrical lead 128. The space between the electrical lead 128 and the plug 126 is sealed. Preferably, the plug 126 is 10 ¹⁴ -10 ¹⁵ Manufactured from ethylene propylene rubber with electrical resistance of Ω-cm. The inner shell 124 is 10 ¹⁴ It is desirable to have an electrical resistance of Ω-cm.
[0042]
FIG. 14 shows a preferred filament 32 for the electron generator used in the accelerators 100 and 130 (FIGS. 12 and 13). The filament 32 is formed in a substantially W shape by a series of curves. This allows the filament 32 to expand and contract during operation without the need for support by an elastic member or a member loaded with spring force. The end of the filament 32 is bent into a hairpin shape as shown in FIG. 14, so that the end can be inserted into an opening or slot in the electrical leads 26a and 26b. If necessary, a plurality of filaments 32 can be used.
[0043]
As shown in FIG. 15, if necessary, the holes 22a of the support plate 22 in the accelerators 100 and 130 (FIGS. 12 and 13) are filled or filled so that the resulting emitted electron beam crosses the beam. And have a variable density profile. Alternatively, instead of filling or filling the holes 22a, the holes 22a can be disposed in the support plate 22 to form a desired pattern of hole distribution during manufacture. Although a specific shape 142 is shown in FIG. 15, any desired shape can be formed.
[0044]
As shown in FIG. 16, the extension nozzle 144 can be secured to the accelerators 100 and 130 (FIGS. 12 and 13) as required. In this case, the radiation window 24 can be disposed at the tip of the nozzle. The nozzle 144 can be inserted into narrow openings such as cups and bottles and used to sterilize the interior.
[0045]
The electronic accelerator of the present invention is suitable for liquid, gas (such as air) or surface sterilization, as well as medical products, food, hazardous medical waste and hazardous waste purification. Other applications include ozone generation, fuel spraying, and chemical bonding of materials. Furthermore, the electron accelerator of the present invention can be used for curing inks, coatings, adhesives and sealants. In addition, materials such as polymers can be cross-linked while irradiated with an electron beam to improve structural properties.
[0046]
The series of openings 35 in the filament housing 30 form a passive field line shaper that changes the shape of the field lines, in particular a flattener that flattens the field lines. The term “passive” means that the electric field lines are formed without the need for a separate extractor power supply. The electric field line can be formed using a plurality of filaments. In addition, partition lines or passive electrodes can be placed between the filaments to form the electric field lines in another shape. Multiple filaments, septa or passive electrodes can be used as a flattener that flattens and other shapes the electric field lines.
[0047]
While the invention has been illustrated and described in terms of preferred embodiments, those skilled in the art will recognize that various changes in shape or detail may be made without departing from the spirit and scope of the invention as defined in the appended claims. It will be understood that it is feasible.
[0048]
For example, while certain embodiments of the present invention have been described with multiple filaments, in an alternative method, only one filament can be used. In addition, the outer shell (except for the ceramic outer shell 102), end cap, and filament housing are preferably made from stainless steel, but alternative methods include other suitable metals such as titanium, copper, Alternatively, KOVAR (registered trademark) or the like can be used. The end caps 16, 20 are typically welded to the outer shell 14, but can be brazed instead. The hole 22a of the support plate 22 can be a non-circular shape such as a slot. The dimensions of the filament 32 and the outer diameter of the accelerator 10 can be changed depending on the application. Also other suitable materials such as glass can be used for the insulator 28.
[0049]
Preferably, the thickness of the titanium radiation window is less than 12.5 μm (6-12 μm), but can be thicker than 12.5 μm for specific applications, if desired. For radiation windows thicker than 12.5 μm, the high voltage power supply needs to supply approximately 100 kV to 150 kV. If the radiation window is made of a material that is lighter than titanium (such as when using aluminum), the same electron beam characteristics can be obtained while making the radiation window thicker than the corresponding titanium radiation window. it can. Preferably, the accelerator has a cylindrical cross section, but may have other suitable shapes, such as a rectangular or elliptical cross section. If the accelerator of the present invention is manufactured in large quantities to reduce the cost, it can be used as a disposable unit. The receptacle 18 of the accelerator 10, 70 can be arranged perpendicular to the long axis A to save space. Finally, the various structures of different embodiments of the present invention can be combined or omitted.
[Brief description of the drawings]
FIG. 1 is a characteristic diagram in which a graph showing the distribution of electrons in a focused electron beam and a graph showing a state in which electrons are uniformly distributed over the entire width of the electron beam are superimposed.
FIG. 2 is a side sectional view of an electron beam accelerator according to the present invention.
FIG. 3 is a schematic diagram showing power connections of the accelerator of FIG. 2;
FIG. 4 is a cross-sectional end view of the filament housing showing electric field lines.
FIG. 5 is a cross-sectional end view of the filament housing, showing electric field lines when there is no side opening 35;
FIG. 6 is a plan view of a system incorporating a plurality of electron beam accelerators.
FIG. 7 is a schematic end cross-sectional view of a filament housing showing another preferred method of electrically connecting the filaments.
FIG. 8 is a schematic bottom sectional view of FIG. 7;
FIG. 9 is a schematic diagram of another preferred filament arrangement.
FIG. 10 is a schematic diagram of yet another preferred filament arrangement.
FIG. 11 is a side cross-sectional view of another preferred electron beam accelerator.
FIG. 12 is a side cross-sectional view of yet another preferred electron beam accelerator.
FIG. 13 is a side cross-sectional view of yet another preferred electron beam accelerator.
FIG. 14 is a bottom view of another preferred filament arrangement.
FIG. 15 is a plan view showing a support plate with a pattern of filled holes to produce an electron beam with a variable density profile in the transverse direction of the beam.
FIG. 16 is a side view of the extension nozzle.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 22 ... Support plate, 26a, 26b ... Electrical lead wire, 24 ... Radiation window, 30 ... Housing, 31 ... Electron generator, 34, 35 ... Opening (electron transmission region), 35 ... Electric field line shaper, 56 ... Electron, 58 ... Electron beam, 100, 130 ... Electron accelerator, 102, 124, 136 ... Ceramic member, 104, 134 ... Vacuum chamber, 122 ... Outer shell, 124a ... Frustum-shaped hole

Claims (14)

A vacuum chamber comprising an elongate ceramic member having an annular wall portion and the electron beam emission window continuous ceramic material having an open end,
A metal end cap covering the open end is attached to the open end of the ceramic annular wall, and the radiation window made of metal foil is joined to the end cap in a metal contact so as to hermetically seal between the two. A vacuum chamber in which the radiation window less than 12.5 μm thick is held by the support plate of the end cap and hermetically sealed to maintain a permanent self-holding vacuum inside;
An electron generator disposed in the vacuum chamber for generating electrons;
A housing surrounding the electron generator, having an electron transmission region formed between the electron generator and a radiation window, wherein electrons are applied when a voltage is applied between the housing and the radiation window. A housing that accelerates as an electron beam from the electron generator to the outside of the radiation window;
Electronic accelerator equipped with.   2. The electron accelerator according to claim 1, wherein the elongated ceramic member is corrugated.   3. The electron accelerator according to claim 2, further comprising an annular spring member engaged between the radiation window and the ceramic member.   2. The electron accelerator according to claim 1, wherein the vacuum chamber further comprises a metal shell surrounding the ceramic member. 5. The electrical lead of claim 4, wherein the ceramic member includes a frustoconical hole, and the electron accelerator further extends through the frustoconical hole to provide power to the electron generator;
A flexible insulating plug having a frustoconical surface surrounding the electrical lead and sealing the frustoconical hole;
A retaining cap secured to the shell and retaining the plug within the frustoconical hole;
Electronic accelerator equipped with.   The electron accelerator of claim 1, wherein the electron transmission region comprises a series of openings in the housing. 2. The electron accelerator according to claim 1, wherein the radiation window is formed of a titanium foil having a thickness of 8 to 10 [mu] m. Te claim 1 odor, comprising a support plate having a series of through holes for passing the electron, the series of holes, electrons transmitted across the support plate to form the electron beam with a variable density profile An electron accelerator that is arranged to change its sex. A vacuum chamber comprising an elongate ceramic member having an annular wall of continuous ceramic material having an open end and an electron beam radiation window;
A metal end cap covering the open end is attached to the open end of the ceramic annular wall, and the radiation window made of metal foil is joined to the end cap in a metal contact so as to hermetically seal between the two. Providing a vacuum chamber in which the radiation window less than 12.5 μm thick is held by the end cap support plate and hermetically sealed to maintain a permanent self-holding vacuum inside;
Generating electrons using an electron generator disposed in the vacuum chamber;
The electron generator is surrounded by a housing, the housing has an electron transmission region formed between the electron generator and the emission window, and when a voltage is applied between the housing and the emission window Accelerating electrons from the electron generator to the outside of the radiation window as an electron beam;
Accelerating electrons containing. 10. The method of claim 9, wherein providing the vacuum chamber further comprises corrugating the elongated ceramic member. 11. The method of claim 10, wherein providing the vacuum chamber further comprises engaging an annular spring member between the radiating window and a ceramic member. 10. The method of claim 9, wherein providing the vacuum chamber further comprises enclosing the ceramic member with a metal shell. In claim 12, the step of providing the vacuum chamber, wherein the ceramic member and the including step the frustoconical hole,
Generating the electrons by extending an electrical lead through the frustoconical hole to provide power to the electron generator;
Enclosing the electrical lead with a flexible insulating plug with a frustoconical surface that seals the frustoconical hole;
Holding the plug in the frustoconical hole using a holding cap secured to the shell;
Including methods. In claim 9, the step of providing the vacuum chamber, in addition, before Symbol support plate has a series of holes through the plate for passing the electron beam, said series of holes, a variable density profile Placing the electron beam across the support plate to change the electron transmission to form the electron beam.

Images