JP3277474B2 - Synchrotron ring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchrotron ring, and more particularly to a method for removing a large amount of gas generated by irradiating the inner wall of a vacuum container with synchrotron radiation generated in a vacuum container of the synchrotron ring. And a gas elimination device for maintaining an ultra-vacuum inside the vacuum vessel.

[0002]

2. Description of the Related Art FIG. 2 shows a synchrotron ring of a race track type. This synchrotron ring is
The electron or positron accelerated by the injection accelerator 200 orbits along a racetrack-type orbit.
Hereinafter, the case of electrons will be described as an example. For this reason, this synchrotron ring has a race track type vacuum vessel 1. Each of the pair of deflecting units 201 is formed of a deflecting electromagnet, and is provided outside the vacuum vessel 1 to deflect the electron beam 2 within the vacuum vessel 1 so as to follow a pair of arc-shaped orbits. Around the vacuum vessel 1 that determines two linear trajectories that communicate between a pair of arc-shaped orbits, an incident electromagnet 202 that enters the electron beam 2 from the accelerator 200 for incidence into the vacuum vessel 1, Eight converging electromagnets 203 composed of quadrupole electromagnets are arranged. The high-frequency accelerating cavity 204 is provided on a linear trajectory different from the linear trajectory on which the incident electromagnet 202 is provided,
It has a function of accelerating the electron beam 2.

In this manner, the synchrotron ring causes the electron beam 2 to circulate and accumulate in the vacuum vessel 1 along a predetermined orbit including an arc-shaped orbit. At this time, when the electron beam 2 is accumulated, the synchrotron radiation 3 is generated in the deflecting unit 201 in the tangential direction of the movement of the electron beam 2. Since the synchrotron radiation 3 irradiates the inner wall of the vacuum vessel 1, a large amount of gas is generated, the degree of vacuum deteriorates, and the storage life of the electron beam 2 is shortened.

[0004] Referring to FIG. 3, a conventional synchrotron ring is a vacuum elimination device that eliminates gas generated in the vacuum vessel 1 when the inner wall of the vacuum vessel 1 is irradiated with synchrotron radiation 3. Exhaust pumps 5 and 8
It has. The central portion of the vacuum vessel 1 is formed with an inner wall of the vacuum vessel 1 and a slit 6 in order to stably circulate the electron beam 2.
And 7 constitute the beam duct unit 100. An evacuation pump 5 is arranged via a slit 6 outside the orbit of the electron beam 2, and an evacuation pump 8 is arranged via a slit 7 inside the orbit of the electron beam 2. In addition, a beam dump 4 is provided in a portion irradiated with the synchrotron radiation 3 to reduce gas generated by a means for cooling the beam dump 4 and the like.

[0005] As shown, the vacuum pumps 5 and 8 and the slits 6 and 7 are provided on both sides of the virtual neutral surface 102.

[0006]

The inside of the vacuum vessel 1 is evacuated to a medium vacuum by a roughing exhaust pump (not shown) provided outside, and the built-in vacuum exhaust pumps 5 and 8 are provided.
Evacuates to an ultra-high vacuum. However, when the electron beam 2 accumulates, the synchrotron radiation 3 irradiates the inside of the vacuum vessel 1, so that a large amount of gas is generated as described above. At this time, the exhaust gas is exhausted by the vacuum exhaust pump 5 while restricting the presence of the generated gas to the portion B in the figure by the slit 6, thereby preventing the gas duct 100 from entering the beam duct portion 100 and the inside of the beam duct portion 100 where electrons circulate. Is to be maintained in an ultra-high vacuum, but a large amount of gas is exhausted by the vacuum exhaust pumps 5 and 8 (mainly by the vacuum exhaust pump 5). 2
Will shorten the storage life.

Further, these built-in vacuum pumps 5
And 8 employ ion pumps, cryopumps, and evaporative / non-evaporable getter pumps, which are generally expensive, complicated in structure, unstable in exhaust capacity, contamination / heat generation during activation, and exhaust capacity. There are problems such as shortage.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a gas elimination device which can efficiently and inexpensively and efficiently remove a large amount of gas generated by irradiating the inner wall of a vacuum vessel with synchrotron radiation and maintain the inside of the vacuum vessel at ultra-vacuum. Provided is a synchrotron ring provided with the same.

[0009]

According to the present invention, there is provided a vacuum vessel, a beam duct provided in the vacuum vessel, and a gas removing device for removing gas generated in the vacuum vessel. In the synchrotron ring, the gas elimination device includes at least a pair of electrodes provided in the vacuum vessel and applied with positive and negative voltages, respectively, and the pair of electrodes is formed outside the beam duct unit. The gas duct is electrically suctioned to eliminate or promote the elimination, and the beam duct portion and the chamber formed outside the beam duct portion are separated by a slit. Are separated, and the slit is
A synchrotron ring is obtained, wherein the synchrotron ring is provided with both the pair of electrodes for eliminating or facilitating the removal of the gas generated in the vacuum vessel.

Further, according to the present invention, there is provided a synchrotron ring wherein the pair of electrodes is formed of a non-evaporable getter material or a cryopanel.

[0011]

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 4 shows a cross section of a portion corresponding to the AA cross section of FIG. 2 in the synchrotron ring according to the first embodiment of the present invention. The deflecting unit 201 disposed outside the vacuum vessel 1 is constituted by a deflecting electromagnet including coils 205 and 206 and an iron core 207. In the synchrotron ring according to the first embodiment of the present invention, the other deflecting unit 201 in FIG. 2 has the same structure as in FIG.

FIG. 1 shows a main part of a synchrotron ring according to a first embodiment of the present invention, and shows a vacuum vessel 1 of FIG. 4 and a cross section of the inside thereof. 1, the same parts as those in FIG. 3 are denoted by the same reference numerals.

A chamber formed outside the slit 6 (part B)
, A pair of electrodes 10 is arranged so as to sandwich the virtual neutral plane 102 so as not to interfere with the synchrotron radiation 3. The pair of electrodes 10 extend parallel to the neutral plane 102. The pair of electrodes 10 is insulated and fixed to the vacuum vessel 1 with an insulating material 103. From the pair of electrodes 10,
A pair of electrode lead wires 1 is connected to the outside (in the atmosphere) of the vacuum vessel 1 via a vacuum seal and an insulated terminal 104, respectively.
05 are drawn out, and a pair of electrode leads 105
Is connected to a power supply 11. For example, a positive voltage of several volts to several tens of volts is applied to one of the pair of electrodes 10 by the power supply 11, and the other of the pair of electrodes 10 is, for example, −.
A negative voltage of several volts to several tens of volts is applied. The vacuum vessel 1 is grounded. The pair of electrodes 10 is made of a metal plate such as copper or aluminum, a non-evaporable getter material, or a cryopanel.

The pair of electrodes 10 is generated in the vacuum vessel 1 by irradiating the inner wall of the vacuum vessel 1 with synchrotron radiation 3 generated after the electron beam 2 is accumulated in a race-track orbit. The pair of electrodes 10 electrically aspirate the ionized gas by utilizing the fact that the gas is ionized by the synchrotron radiation 3 into the ionized gas. It is to be excluded. In other words, the electrode of the pair of electrodes 10 to which a positive voltage is applied is one that electrically attracts and removes the negative (negative) ions of the ionized gas, and the positive (positive) ions of the ionized gas is , And the electrode 10 to which a negative voltage is applied among the pair of electrodes 10 is electrically repelled. Conversely, the electrode of the pair of electrodes 10 to which a negative voltage is applied is one that positively removes positive (positive) ions from the ionized gas by electrical attraction and removes negative (negative) ions from the ionized gas. Electrically repels the electrode of the pair of electrodes 10 to which a positive voltage is applied.

FIG. 5 is a sectional view showing a main part of a synchrotron ring according to a second embodiment of the present invention. The same parts as those in FIGS. 1 and 3 are denoted by the same reference numerals. FIG. 5 shows an example in which the pair of electrodes 10 extend perpendicular to the neutral surface 102 and the pair of electrodes 10 is arranged as a baffle (baffle plate).
) Electrode plates.

FIG. 6 is a sectional view showing a main part of a synchrotron ring according to a third embodiment of the present invention. The same parts as those in FIG. 5 are denoted by the same reference numerals. In FIG. 6, a pair of slits 6 are formed on the vacuum container 1 with the insulating material 1.
06, a pair of slits / electrodes 6 are drawn out from the pair of slits / electrodes 6 to the outside (in the atmosphere) of the vacuum vessel 1 via a vacuum seal and an insulated terminal 107, respectively. The wire 108 is drawn out, and the pair of electrode lead wires 108 is connected to the power supply 11 ′. For example, a positive voltage of several volts to several tens of volts is applied to one of the pair of slit / electrodes 6 by the power supply 11 ′, and − is applied to the other of the pair of slit / electrodes 6, for example.
A negative voltage of several volts to several tens of volts is applied.

Similarly, after a pair of slits 7 are insulated from the vacuum vessel 1 with an insulating material 109 to form a pair of electrodes, a vacuum seal and an insulated terminal 109 are formed from the pair of slit / electrodes 7. A pair of electrode lead wires 108 is drawn out of the vacuum vessel 1 (in the atmosphere) via each of them, and the pair of electrode lead wires 108 is connected to a power supply 11 '. For example, a positive voltage of several volts to several tens of volts is applied to one of the pair of slits and electrodes 7 by the power supply 11 ′, and −several volts to several tens of volts is applied to the other of the pair of slits and electrodes 7. Is applied.

By applying a voltage to the slit / electrodes 6 and 7, ionized gas present in the beam duct 100 is removed by suction. It is also possible to remove ions which are ionized by the electron beam 2 itself, are trapped by the electron beam 2 and orbit together with the electron beam 2 (this ion makes the electron beam 2 unstable). Becomes

Although a voltage of several volts to several tens of volts is applied to the slit / electrodes 6 and 7, the electron beam 2 usually has an energy of 600 MeV to 1 GeV. It can be said that the applied voltage has no effect on the electron beam 2.

In FIG. 1, FIG. 5, and FIG. 6, the inside of the vacuum vessel 1 is evacuated to an ultra-high vacuum by the above-described roughing exhaust pump and the built-in vacuum exhaust pump 8, and then the electron beam 2 is accumulated. When the synchrotron radiation 3 emitted by the accumulation of the electron beam 2 irradiates the inner wall of the vacuum vessel 1, a large amount of gas is generated in a portion B in the drawing. Since this gas is present in the portion B, the gas is directly or indirectly ionized by the synchrotron radiation 3 with a high probability and becomes charged. That is, most of the gas (which should be evacuated) which is generated in a large amount in a state where the electron beam 2 is accumulated becomes a ionic state. On the other hand, positive and negative voltages are respectively applied to the pair of electrodes 10, and the ionized gas is drawn to these electrodes and exhausted.

When the electrode 10 is made of a non-evaporable getter material or a cryopanel, the inherent exhaust capability is greatly improved. That is, in the conventional case of FIG. 3, the gas to be evacuated is exhausted in a state of moving randomly because it does not utilize the fact that the gas to be evacuated is ionized, but in this embodiment, the gas to be evacuated is ionized. When the electric field is generated by utilizing the fact that the electric field is generated, the electric field is moved by the electric attraction force or the repulsive force toward the adsorption surface, so that the adsorption efficiency is increased.

In FIGS. 5 and 6, the electrode 10 serving as the suction surface is arranged as a baffle (baffle plate), so that the gas generated on the inner wall of the vacuum vessel 1 is less likely to enter the beam duct 100. Has become.

In FIG. 6, in addition to the case of FIG. 5, positive and negative voltages are applied to the slit / electrodes 6 and 7 constituting the beam duct section 100 from the power supply 11 '. Therefore,
The ion gas existing in the beam duct unit 100 can be exhausted. Further, when the non-evaporable getter material or the cryopanel is used for the slit / electrodes 6 and 7, gas other than the ion gas can be exhausted.

[0026]

As described above, according to the present invention, the gas generated by irradiating the inner wall of the vacuum vessel with the synchrotron radiation in the vacuum vessel of the synchrotron ring is directly or with a high probability due to the synchrotron radiation. The gas is exhausted by the electrode to which the voltage is applied, paying attention to the state of being indirectly ionized and having a charge, and the gas can be efficiently exhausted at low cost. A cheaper metal plate of copper, aluminum, or the like can be used as the electrode. In this case, the structure and operation are simple and inexpensive, and the problem of heat generation and contamination does not occur. When a non-evaporable getter material or a cryopanel is used as the electrode, the inherent exhaust capacity is dramatically improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a synchrotron ring according to a first embodiment of the present invention.

FIG. 2 is a plan view showing the entire structure of a synchrotron ring to which the present invention is applied.

FIG. 3 is a sectional view of a main part of a conventional synchrotron ring.

FIG. 4 is a cross-sectional view of a portion corresponding to the AA cross section of FIG. 2 of the synchrotron ring according to the first embodiment.

FIG. 5 is a sectional view of a main part of a synchrotron ring according to a second embodiment of the present invention.

FIG. 6 is a sectional view of a main part of a synchrotron ring according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Electron beam 3 Synchrotron radiation 4 Beam dump 5 Vacuum exhaust pump 6 Slit (slit and electrode) 7 Slit (slit and electrode) 8 Vacuum exhaust pump 10 Electrode 11 Power supply 11 'Power supply

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-2-288099 (JP, A) JP-A-64-48397 (JP, A) JP-A-3-49200 (JP, A) JP-A 5- 36500 (JP, A) JP-A-2-116798 (JP, A) JP-A-4-133300 (JP, A) JP-A-5-226098 (JP, A) JP-A-6-68993 (JP, A) JP-A-6-162989 (JP, A) JP-A-6-243995 (JP, A) JP-A-6-75054 (JP, A) JP-A-6-20799 (JP, A) JP-A-6-188099 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H05H 13/04

Claims (2)

(57) [Claims] 1. A synchrotron ring comprising a vacuum container, a beam duct provided in the vacuum container, and a gas elimination device for eliminating gas generated in the vacuum container, wherein the gas elimination device is , Including at least a pair of electrodes provided in the vacuum vessel, respectively applied with positive and negative voltage, the pair of electrodes are arranged in a chamber configured outside the beam duct portion, The gas is electrically suctioned to eliminate or promote the elimination, and the beam duct portion and a chamber formed outside the beam duct portion are separated by a slit, and the slit is A synchrotron reactor, which is provided with the pair of electrodes for eliminating or facilitating the removal of gas generated in a vacuum vessel by electrical suction. Grayed. 2. The synchrotron ring according to claim 1, wherein the pair of electrodes are formed of a non-evaporable getter material or a cryopanel.