JPH0817626A - Electromagnet capable of baking-out - Google Patents

Abstract

PURPOSE:To obtain an electromagnet capable of baking-out at a high temperature, by hermetically sealing an exciting coil in a coil case at a high vacuum, in an electromagnet wherein the exciting coil is accommodated in the coil case. CONSTITUTION:An exciting coil 4 wound around an iron core 2 is accommodated in the inside of a coil case 1 so as to leave a comparatively large space 5, which inside is constituted of the iron core 2 and the coil case 1. A current introducing terminal 3 of the exciting coil 4, and an exhaust pipe 7 for vacuumizing the inside of the coil case 1 containing the exciting coil 4 and the space 5 are installed. The current introducing terminal 3 is insulation-sealed by using alumina insulator 9. A cooling water channel 6 is installed in the coil case 1 itself, and cooling is performed by water flow when an electromagnet 11 is operated. Thereby deformation or rupture is not generated when the pressure in the coil case is increased, so that baking-out at a high temperature is enabled and an electromagnet applicable to an electron beam evaporation source can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnet which can be baked out, and more particularly to an electromagnet which does not deform or rupture a coil case during baking at high temperature.

[0002]

2. Description of the Related Art Among electromagnets, in an electromagnet used in a high temperature and harsh atmosphere, an exciting coil is generally housed in a coil case. For example, in an electromagnet used in contact with high temperature metallic sodium as a coolant in a fast breeder reactor, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent No. 165088, the coil 45 wound around the inner core 46 is housed in a coil case 47, and the coil case 47 is filled with an inert gas at a pressure higher than the pressure of the coolant sodium. Then, the coil wire 51 is formed by coating the electric conductors 54, 57 and 59 with an inorganic substance to form the insulating layer 56.

Further, in a vacuum vapor deposition apparatus or a vacuum melting apparatus, an electron beam evaporation source used in a vacuum chamber is provided with an electromagnet for deflecting an electron beam.
The coil of this electromagnet is sealed in the coil case at atmospheric pressure.

When high-purity vapor deposition or melting is required, operation under an ultra-high vacuum system is required, and in that case, no gas is released from the vacuum chamber or the electron beam evaporation source itself. First, they must be previously baked out and degassed. When the electron beam evaporation source is baked out, the electromagnet for deflecting the electron beam provided therein emits the gas adsorbed to the coil case and other parts, and is also generated from the exciting coil in the coil case. When gas is present, it also diffuses in the coil case material and is released.

As described above, as the electromagnet provided in the conventional electron beam evaporation source, the one in which the exciting coil is sealed in the coil case at atmospheric pressure is used. Therefore, when heating in a vacuum for bake-out, the pressure in the coil case becomes large and the coil case is deformed or ruptured. Therefore, the heating temperature at the time of bake-out is limited to about 100 ° C. there were. On the other hand, increasing the pressure of the inert gas to fill the coil case rather limits the bakeout temperature.

Under the circumstances described above, the vacuum apparatus equipped with the electron beam evaporation source cannot raise the bakeout temperature, and the application of the electron beam evaporation source to the ultra-high vacuum system has caused various obstacles. .

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object thereof is to provide an electromagnet capable of being baked out at a high temperature.

[0008]

The above object is characterized in that, in an electromagnet in which an exciting coil is housed in a coil case, the exciting coil is sealed under vacuum in the coil case. Achieved by an electromagnet.

[0009]

[Function] Since the exciting coil of the electromagnet is hermetically sealed in the coil case under vacuum, the pressure in the coil case does not become high even if it is baked out at a high temperature, so that the coil case is deformed or bursts. There is no such thing.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An electromagnet capable of being baked out according to the present invention will be described below with reference to the drawings.

FIG. 1 is an axial sectional view of an electromagnet 11 of this embodiment, and FIG. 2 is a view taken along the line [2]-[2] in FIG. 1, showing a state before sealing. That is, the iron core 2
The exciting coil 4 for winding the coil has a relatively large space inside the coil case 1 composed of the iron core 2 and the coil case 1.
It is housed with 5 left. Then, the current introducing terminal 3 of the exciting coil 4 and the exhaust pipe 7 for vacuuming the inside of the coil case 1 including the exciting coil 4 and the space 5 are attached. The current introducing terminal 3 is made of alumina insulating material 9
Insulated by. In addition, a cooling water passage 6 is provided inside the coil case 1 itself, and water is cooled when the electromagnet 11 is activated. The exciting coil 4
The conductive wire of (1) is used as a jacket insulating material coated with polyimide.

The operation of sealing the exciting coil 4 together with the space 5 in the coil case 1 under vacuum is performed according to the procedure shown in FIG. First, a terminal tube 31 of a vacuum exhaust line (not shown) is connected to the end of the exhaust pipe 7 and the exhaust pipe 7 is exhausted to a pressure of 10 ^-2 Pa in the direction of the white arrow (A in FIG. 3). Next, while continuing the exhaust, the exhaust pipe 7 is pressed from above and below as indicated by the black arrow by the press-contact tool 25. (B in FIG. 3). Further, the tip end 7a of the exhaust pipe 7 which is pressure-welded is arc-welded so as to make it solid (C in FIG. 3).

FIG. 4 is a schematic view showing the electron beam evaporation source 10 to which the electromagnet 11 of this embodiment is attached. A in FIG. 4 is a front view seen from the tungsten filament 15 side, and FIG. 4B is a view. 4 is a view in the direction of the [B]-[B] line in A of FIG. That is, in FIG. 4A, the electromagnet 11 is provided below the water-cooled copper hearth 17, and the magnetic force line 14 draws a loop from the magnetic pole 12 to the electromagnet 11 via the magnetic pole 13 as shown by a broken line. And FIG.
2B, the electron beam 16 shown by the thin line generated from the tungsten filament 15 is deflected by the formed magnetic field and irradiates the evaporation material 18 in the water-cooled copper hearth 17, and the evaporation material 18 is heated and melted. And is further vaporized as a vapor stream 19 shown by a chain line. The water-cooled copper hearth 17 and the electromagnet 11 are respectively water-cooled pipes 21 and 22.
Cooled by. In order to avoid complication of the drawing, the electron beam 16 is omitted in A of FIG. 4 and the magnetic field line 14 is omitted in B of FIG.

For example, when performing vacuum deposition in an ultra-high vacuum system, as described above, the electron beam evaporation source 10 is heated under vacuum together with the vacuum chamber and adsorbed H ₂ O, CO, and Degassing of other gases, that is, bakeout is performed. The electromagnet 11 of this embodiment can be bake out by draining the cooling water from the cooling water passage 6 to empty it and then heating it to a high temperature in the temperature range of 250 to 400 ° C. Excitation coil 4, space 5 even when heated to such a high temperature
This is because the inside of the coil case 1 including is not evacuated and the coil case 1 is not deformed or ruptured.
By this high temperature bake-out, the gas release rate after bake-out can be reduced within a range of 1 to 2 digits as compared with the conventional bake-out at a temperature of about 100 ° C.

Although the embodiment of the present invention has been described above, the present invention is not limited to this, and various modifications can be made based on the technical idea of the present invention.

For example, in the present embodiment, the exciting coil 4,
The inside of the coil case 1 including the space 5 is set to a pressure of 10 ^-2 Pa, but it may be set to a pressure of about 10 ^-4 Pa if necessary, or a vacuum of about 1 Pa in some cases.

Further, since the coil case 1 is evacuated as described above, even if a small amount of gas is generated from the coating of the conductive wire of the exciting coil 4, the pressure inside the coil case 1 hardly rises. In this respect, in the past, as a conductor wire that can withstand high temperatures, only an inorganic coated wire which is poor in flexibility and expensive can be used, whereas the electromagnet 1 of the present invention can be used.
In No. 1, a flexible and heat-resistant practical polyimide coated wire can be used. Instead of this polyimide, heat resistant and flexible such as aromatic polyamide or tetrafluoroethylene-based polymer. A conductor wire coated with an organic polymer having a large size may be used. If a high temperature bake-out is not required, a general cross-linked polyethylene coated wire may be used. Furthermore, instead of organic heat-resistant polymer, S
It is possible to further increase the upper limit temperature of bakeout by using a conductive wire coated with an inorganic substance such as iO ₂ , Al ₂ O ₃ and MgO.

Further, although the electromagnet capable of bakeout of the present embodiment is described as being used for an electron beam evaporation source, it can be used for electromagnets in other high temperature fields, and it has acid resistance and alkali resistance. If necessary, the whole may be coated with a heat-resistant and chemical-resistant organic polymer such as a tetrafluoroethylene-based polymer.

[0019]

As described above, according to the electromagnet capable of bakeout of the present invention, since the inside of the coil case is under a high pressure and no deformation or rupture occurs, it is possible to bake out at a high temperature. By applying this electromagnet to an electron beam evaporation source for deflecting an electron beam, vacuum vapor deposition under an ultrahigh vacuum, vacuum melting and the like are possible.

Also, since the electromagnet of the present invention capable of bakeout has a vacuum inside the coil case, even if a small amount of gas is generated from the conductor of the exciting coil, the internal pressure hardly rises. , And requires little consideration of the gas released from the coating material. Furthermore, because it is a vacuum,
There is no need to consider oxidation of the coating material of the conductor or other chemical reaction with the outside air.

[Brief description of drawings]

FIG. 1 is an axial cross-sectional view of an electromagnet capable of bakeout according to an embodiment.

FIG. 2 is a view taken along the line [2]-[2] in FIG.

FIG. 3 is a diagram showing a procedure of sealing an exciting coil under vacuum in the electromagnet of the present embodiment.

FIG. 4 is a schematic view of an electron beam evaporation source having an electromagnet according to the present embodiment, where A is a front view and B is a partially omitted side view.

[Explanation of symbols]

1 Coil Case 2 Iron Core 3 Current Introducing Terminal 4 Excitation Coil 5 Space 6 Cooling Channel 7 Exhaust Pipe 9 Insulating Sealing Material for Current Introducing Terminal 10 Electron Beam Evaporation Source 11 Bakeout-enabled Electromagnet

Claims (3)

[Claims] 1. An electromagnet in which an exciting coil is housed in a coil case, wherein the exciting coil is sealed under vacuum in the coil case. 2. The electromagnet according to claim 1, wherein the conductive wire used in the exciting coil is coated with an organic heat-resistant polymer made of any one of polyimide, aromatic polyamide, and tetrafluoroethylene-based polymer. 3. The electromagnet according to claim 1, which is attached to an electron beam evaporation source for deflecting the electron beam.