JPH07249500A - Supporting structure of non-evaporative getter pump - Google Patents

Abstract

PURPOSE:To shut off the radiation heat radiated from a NRG strip using heat shield. CONSTITUTION:The body 13 of a vacuum chamber is structured hollow and. equipped with sides confronting each other at a certain spacing and an over-anti- under coupling part continuing to the sides, and inside of this chamber body 13 a support arm 21 is installed while a certain spacing is reserved in the extending direction of the chamber body 13. The support arm 21 is fitted with a NEG strip 17 which stretches in the chamber body extending direction. A heat shield 28, which covers this NFG strip 17 being insulated therefrom electrically, and the support arm 21 are mounted on the chamber body 13 through a washer 29.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support structure for a non-evaporable getter pump.

[0002]

2. Description of the Related Art When an electron moving at a speed close to the speed of light is bent in its traveling direction by a magnetic field or an electric field, an electromagnetic wave (light) called radiated light is emitted in the tangential direction of the orbit of the electron.

FIG. 3 shows an example of means for generating synchrotron radiation. Reference numeral 1 denotes a linear accelerator (particle accelerator), which is a straight tube for transferring electrons (charged particles) e. It has an acceleration duct 2.

The acceleration duct 2 is formed so that the inside thereof can be maintained in an ultrahigh vacuum, and a high frequency is applied to the electrons e moving inside the acceleration duct 2 held in the ultrahigh vacuum state to accelerate the electrons e. A high frequency accelerating device 3 is provided.

An electron generator 4 such as an electron gun is provided at one end of the acceleration duct 2, and electrons e generated by the electron generator 4 are emitted toward the hollow portion of the acceleration duct 2. It has become so.

Further, one end of a curved tubular deflection duct 5 is connected to the other end of the acceleration duct 2, and a deflection electromagnet 6 is provided on the curved portion of the deflection duct 5.

Thus, the electron e entering the deflection duct 5 from the acceleration duct 2 can be bent along the deflection duct 5 in the traveling direction by the magnetic field of the deflection electromagnet 6.

Electrons e moving inside the deflection duct 5
Is not accelerated to a speed close to the speed of light, so that it does not emit radiated light even if the traveling direction is bent by the magnetic field of the deflection electromagnet 6.

Reference numeral 7 is a synchrotron, and the synchrotron 7 has a circular duct 8 for causing the electron e to form a circular orbit, and the deflection duct is provided at a required position of the circular duct 8. The other end of 5 is connected.

The inside of the circular duct 8 can be maintained in an ultrahigh vacuum. A bending electromagnet 9 is provided on the curved portion of the circular duct 8 so that the electrons e entering from the deflecting duct 5 into the circular duct 8 held in an ultrahigh vacuum are provided.
The traveling direction is bent along the circular duct 8 by the magnetic field of the deflection electromagnet 9 so as to circulate inside the circular duct 8.

On the other hand, a high frequency accelerating device 10 is provided at a required position of the circular duct 8, and the electrons e circulating inside the circular duct 8 are given a high frequency by the high frequency accelerating device 10 to generate the speed of light. It is designed to accelerate to a speed close to.

Further, the required curved portion of the circular duct 8 has an electron e which moves at a velocity close to the speed of light in the curved portion.
One end of a straight tubular horizontal beam channel 11 for guiding the radiant light beam S emitted by bending the traveling direction of the beam is connected to the outside of the circular duct 8.

Reference numeral 12 denotes an experimental device, and the experimental device 12
Is connected to the other end of the beam channel 11.

The radiant light beam S emitted from the circular duct 8 to the beam channel 11 is guided to the experimental device 12.

The circular duct 8 is constructed so as to connect a plurality of vacuum chamber bodies 13 having a cross section as shown in FIG. Inside the vacuum chamber body 13, a beam chamber 14 extending in the traveling direction of the electron beam, a pump chamber 15 extending along the beam chamber 14, and a slot portion communicating the beam chamber 14 and the pump chamber 15 with each other. 16
And are provided.

Inside the pump chamber 15,
NEG (Non Evapo) that constitutes the getter pump
A rable getter strip 17 is supported on the vacuum chamber body 13 in an electrically insulated state.

4 and 5 schematically show an example of the support structure of the NEG strip 17 in the vacuum chamber body 13, and in this example, along the upper and lower surfaces of the inner circumference of the pump chamber 15 of the vacuum chamber body 13, respectively. One row of NEG strips 17, 17 is provided.

Two grooves 1 extending in the longitudinal direction of the pump chamber 15 are formed on the upper and lower inner peripheral surfaces of the pump chamber 15 of the vacuum chamber body 13.
8 is formed, and the base plate 2 is made of aluminum or the like in the groove 18 and has a plurality of screw holes 19 formed at predetermined intervals in the longitudinal direction.
0 and 20 are inserted and attached respectively.

A plurality of support arms 21 made of a thin strip of aluminum or the like are attached to the base plates 20 and 20 by being tightened by a plurality of fixing members 22 which can be screwed into the screw holes 19. There is.

The above-mentioned support arm 21 is bent in a U-shape, and both ends on the open side formed by opening and closing,
When mounted inside the pump chamber 15, each is bent outward in such a manner that it becomes substantially horizontal, and is further folded back inward. The widthwise ends of the NEG strip 17 are formed at both ends bent inward. Is formed so as to fix and support the NEG strip 17 by sandwiching both side edges thereof, and has a hole through which the threaded portion of the fixing member 22 can be inserted, in a substantially central portion of the bottom portion in contact with the base plate 20, and It is formed so as to be electrically insulated from the base plate 20 by applying a ceramic coating 23 on both upper and lower surfaces of the bottom portion or by interposing a spacer made of ceramics or the like.

The NEG strip 17 is a ribbon-shaped one having a width of 30 mm and a thickness of about 0.2 mm formed by vacuum-depositing powder of zirconium, vanadium, etc. on a thin plate of constantan.
When zirconium and vanadium are activated by raising the temperature to about 0 ° C., the zirconium and vanadium have a property of adsorbing gas molecules.

In the above vacuum chamber body 13, the inside of the pump chamber 15, the slot portion 16 and the beam chamber 14 is decompressed by a mechanical pump such as a turbo pump (not shown), and a voltage is applied to an electrode (not shown). Then, a current (about 70 to 90 A) flows through the NEG strips 17, 17. As a result, the NEG strips 17, 1
7 is heated to about 450 ° C. by Joule heat. NE
When zirconium and vanadium are activated by heating the G strips 17 and 17 to about 450 ° C. and raising the temperature, the zirconium and vanadium adsorb gas molecules and the inside of the vacuum chamber main body 13 is 10 ⁻⁹ to 10 ^{−. Ten}
An ultrahigh vacuum state of about Torr is set.

[0023]

However, in the above-mentioned support structure for the non-evaporable getter pump, when the temperature of the NEG strip 17 arranged in the vacuum chamber body 13 is raised, the radiant heat emitted from the NEG strip 17 is emitted. The temperature of the received chamber body 13 is about room temperature, and the temperature difference between the chamber body 13 and the NEG strip 17 is large, which causes a large amount of electric power required to raise the temperature of the NEG strip 17.

Further, there is a problem that the chamber body 13 may be deformed if it receives too much radiant heat.

In view of the above-mentioned situation, the present invention suppresses the transfer of heat from the NEG strip to the vacuum chamber main body when the temperature of the NEG strip is raised, and
It is an object of the present invention to provide a support structure for a non-evaporable getter pump that can reduce the power for heating the strip and prevent the deformation of the vacuum chamber body.

[0026]

In order to achieve the above object, in the support structure of the non-evaporable getter pump of the present invention,
A support arm is arranged inside the vacuum chamber body having a hollow structure at a predetermined interval in the extension direction of the vacuum chamber body, and a NEG strip extending in the extension direction of the vacuum chamber body is attached to the support arm, and the NEG strip is attached. A heat shield covering and electrically insulated from the NEG strip is attached to the vacuum chamber body via the electrically insulating member along with the support arm. In addition, it is preferable that a large number of holes for allowing gas molecules to flow are formed in the heat shield.

Further, if the cross section of the heat shield is U-shaped or circular, the rigidity of the heat shield itself is improved.

[0028]

In the present invention, the heat shield blocks the radiant heat of the NEG strip and suppresses the movement of heat.

When a large number of holes are provided in the heat shield, the holes enhance the flow of gas molecules and promote the progress of vacuuming in the vacuum chamber body.

Further, when the cross section of the heat shield is U-shaped or circular, deformation of the heat shield due to heat is suppressed.

[0031]

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2 show the outline of one embodiment of the support structure of the non-evaporable getter pump of the present invention.
In the figure, the same parts as those in FIG.

The heat shield 28 shown in this embodiment has the following structure.

That is, it has a bottom surface 24 having a required width and extending in the extension direction of the base plate 20, and a side surface 25 which is continuous with both side portions of the bottom surface 24 in the width direction and rises with a curved surface bulging outward. The side surface 25 is formed so that each tip edge portion thereof has a substantially U-shaped cross section facing each other with a predetermined space therebetween, and can cover the support arm 21 and the NEG strip 17, and further, in the height direction of the side surface 25 and A large number of elongated holes 26 extending in the longitudinal direction, which are arranged at predetermined intervals in the longitudinal direction, are provided, and the bottom surface 24 has
Holes 27 through which the threaded portions of the fixing member 22 can be inserted are provided at substantially the same intervals as the pitch of the threaded holes 19 formed in the base plate 20.

Fixing member 22 formed of an electrical insulator
A plurality of washers 29 having holes through which the screw portions of the heat shield 28 are inserted are arranged at the positions of the screw holes 19 provided in the base plate 20, and the heat shield 28 is provided on the bottom face 24 of the heat shield 28. 27 is placed so as to match the location of the washer 29, and each support arm 21 is mounted on the washer 29, and both open end portions of the support arm 21 are oriented in the width direction of the base plate 20 and are made of ceramic. It is arranged so that the outer surface on the closed side with the coating 23 abuts on the washer 29, and the screw portion of the fixing member 22 is inserted into the hole on the bottom surface of the support arm 21 and the base plate 2
By screwing into the screw hole 19 of 0 and tightening,
The washer 29, the heat shield 28, and the support arm 21 are fixed on the base plate 20.

Then, both side edges of the NEG strip 17 in the width direction are placed on the bent portions of the front end portions of the support arm 21 on the open side, and the bent portions are pressed to perform NE.
By sandwiching both side edges of the G strip 17, the NEG strip 17 is stretched inside the pump chamber 15 of the vacuum chamber body 13.

According to the above, since the NEG strip 17 is formed by the heat shields 28 having the long holes 26 on both side surfaces, the heat generated by the radiant heat emitted from the heat shield 28 and absorbed in the vacuum chamber body 13 is absorbed. Since the movement can be suppressed and the gas molecules can pass through the long hole 26, the heat shield 28 does not hinder the progress of the vacuumization inside the vacuum chamber body 13.

Further, since the cross section of the heat shield 28 is formed in a substantially U shape, the rigidity of the heat shield 28 is increased, and the heat shield 28 is less likely to be thermally deformed.

In order to increase the rigidity of the heat shield 28, it is possible to use one having a circular cross section.

In the embodiment described above, the heat shield 2
The NEG strip 17 may be covered by another heat shield having a U-shaped opening facing upward, but having a cross-sectional shape such that the U-shaped opening faces sideways or downwards. Slot 2 for heat shield 28
A hole having a shape different from that of 6 may be formed.

Further, as long as the cross-sectional shape of the heat shield 28 is a shape having an opening, gas molecules flow through the opening, so that it is possible to omit the formation of the hole.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

[0043]

According to the support structure of the non-evaporable getter pump of the present invention, various excellent effects as described below can be obtained.

I) According to the first aspect, the NEG strip is formed by the heat shield so as to cover the NEG strip, and the transfer of heat due to the radiant heat radiated from the NEG strip and absorbed in the vacuum chamber body is suppressed. Electric power for raising the temperature can be saved, and deformation of the vacuum chamber body can be prevented.

II) According to claim 2, the gas molecules can pass through a large number of holes provided in the heat shield, so that the heat shield does not hinder the progress of vacuuming inside the vacuum chamber body.

III) According to claims 3 and 4,
Because the rigidity of the heat shield is improved due to the cross-sectional shape,
It is possible to prevent deformation of the heat shield due to heat.

[Brief description of drawings]

FIG. 1 is a cross-sectional view schematically showing an embodiment of a support structure for a non-evaporable getter pump according to the present invention.

FIG. 2 is a perspective view schematically showing a heat shield related to FIG.

FIG. 3 is a configuration diagram illustrating an outline of an example of a unit that generates radiated light.

FIG. 4 is a cross-sectional view schematically showing an example of a vacuum chamber of a conventional particle accelerator related to FIG.

FIG. 5 is a schematic cross-sectional view of a NEG strip support device related to FIG. 4;

[Explanation of symbols]

 13 Vacuum Chamber Main Body 17 NEG Strip 21 Support Arm 26 Long Hole (Hole) 28 Heat Shield 29 Washer (Electrically Insulating Member)

Claims (4)

[Claims] 1. A vacuum chamber body having a hollow structure is provided with support arms at predetermined intervals in the extension direction of the vacuum chamber body, and a NEG strip extending in the extension direction of the vacuum chamber body is attached to the support arm. ,
A support for a non-evaporable getter pump, characterized in that a heat shield that covers the NEG strip and is electrically insulated from the NEG strip is attached to the vacuum chamber body together with the support arm via an electrically insulating member. Construction. 2. The support structure for a non-evaporable getter pump according to claim 1, wherein a large number of holes for passing gas molecules are formed in the heat shield. 3. The support structure for a non-evaporable getter pump according to claim 1 or 2, wherein the heat shield has a U-shaped cross section. 4. The support structure for a non-evaporable getter pump according to claim 1, wherein the heat shield is formed in a circular cross section.