Electron microscope
The present invention is to provide an electron microscope capable of being activated to an appropriate temperature by disposing an NEG at an extraction electrode around an electron source. The present invention is an electron microscope provided with an electron gun, in which the electron gun includes an electron source, an extraction electrode, and an accelerating tube, the accelerating tube is connected to the extraction electrode at a connection portion, the extraction electrode includes a first heater and a first NEG, and the first heater and the first NEG are spaced apart in an axial direction of an electron beam emitted from the electron source.
1. An electron microscope comprising:
an electron gun, wherein
the electron gun includes an electron source, an extraction electrode, and an accelerating tube,
the accelerating tube is connected to the extraction electrode at a connection portion,
the extraction electrode includes a first heater and a first NEG,
the first heater and the first NEG are spaced apart in an axial direction of an electron beam emitted from the electron source, and
the first heater is arranged on an outer surface of the extraction electrode extending in the axial direction of the electron beam.
2. The electron microscope according to claim 1 , further comprising:
a second heater that is disposed around the accelerating tube.
3. The electron microscope according to claim 2 , wherein
the first NEG is provided between the first heater and the connection portion.
4. The electron microscope according to claim 3 , wherein
the first heater is heated to 400° C. or higher,
the second heater is heated to 300° C. or higher,
the connection portion is heated by the second heater to a temperature lower than a temperature of the second heater, and
a temperature of the first NEG is higher than a temperature of the connection portion and lower than a temperature of the first heater.
5. The electron microscope according to claim 4 , wherein
the first heater is disposed in a vacuum container inside the electron gun.
6. The electron microscope according to claim 5 , wherein
the second heater is disposed outside the vacuum container.
7. The electron microscope according to claim 6 , further comprising:
an ion pump, wherein
a second NEG is provided between an electrode having a ground level of the accelerating tube and the ion pump.
8. An electron microscope comprising:
an electron gun, wherein
the electron gun includes an extraction electrode and an accelerating tube,
the accelerating tube is connected to the extraction electrode at a connection portion,
the extraction electrode includes a first heater and a first NEG, the first heater heats the extraction electrode by constantly energizing during baking of the electron gun, and
the first NEG is heated by a thermal gradient between the first heater and the connection portion,
the first heater is arranged on an outer surface of the extraction electrode extending in the axial direction of the electron beam; and
the first heater and the first NEG are spaced apart in an axial direction of an electron beam emitted from the electron gun.
9. The electron microscope according to claim 8 , further comprising:
a second heater for baking the electron gun around the accelerating tube.
10. The electron microscope according to claim 9 , wherein
the first NEG is provided between the first heater and the connection portion.
11. The electron microscope according to claim 10 , wherein
the first heater is heated to 400° C. or higher,
the second heater is heated to 300° C. or higher,
the connection portion is heated by the second heater to a temperature lower than a temperature of the second heater, and
a temperature of the first NEG is higher than a temperature of the connection portion and lower than a temperature of the first heater.