JPS6240344Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an ion gun that generates field ions from a highly reactive liquid metal using electrohydrodynamics (EHD).

As an ion gun for generating an ion beam in an ion microanalyzer, etc., an ion gun that generates field ions using EHD rather than liquid metal has been proposed. In this type of ion gun, when a liquid metal such as cesium is highly reactive with air or moisture in the air and is extremely difficult to handle in the air, it is difficult to use the liquid metal as the ion species. It is necessary to safely introduce the ion gun into the ion gun without causing any reaction with other substances. The reactive metals mentioned above are used in a vacuum-evacuated state sealed in glass ampoules, but conventional equipment can safely load reactive metals without reacting with air, etc. I stopped talking.

This idea was made in view of the above points.The ampoule stored in the ampoule storage space is provided with a thermal expansion material for crushing under vacuum, and the thermal expansion material is expanded by applying heat from the outside. The purpose of the present invention is to provide an ion gun that expands and presses an ampoule to break it, loads a reactive metal into the ion gun without contacting it with air, and safely and stably generates field ions.

The present invention includes an evacuated storage space for storing an ampoule of reactive metal and communicating with a reservoir portion of the metal, a thermal expansion material for crushing the ampoule, and a means for heating the thermal expansion material. This is an ion gun that is characterized by the following.

The present invention will be explained below with reference to the drawings. FIG. 1 is a vertical sectional view showing an ion source according to an embodiment of the invention, FIG. 2 is a partially enlarged view thereof, and FIG. 3 is a partially enlarged view showing the operating state.

In the drawing, 1 is a capillary/needle type
As shown in FIG. 2, the details of the EHD emitter section include a capillary 1a forming a reservoir for liquid metal 2, a capillary 1a that is spot-welded to the base 1b of this capillary 1a, and
It consists of a tungsten needle 1d that projects outside the capillary with a gap 1c formed between it and the tip of the capillary.

The emitter section 1 is fixed to the lower end of the emitter fixing material 3, and the emitter fixing material 3 is fixed to the lower end of the ampoule holder 4. A thermal expansion material 6 is attached to the emitter fixing member 3 with a thermal expansion material fixing fitting 5 interposed therebetween in such a manner that it can be thermally expanded. An ampoule 8 containing liquid metal 2 is stored in the ampoule storage space 7, and one end of the ampoule 8 is brought into contact with the thermal expansion material 6 by the ampoule holder 4.
It is stored more prominently. The ampoule holder 4 is fixed to a cap 9, which includes a high voltage introduction terminal 15 and a heat shielding plate 1 having a reflective function.
0 is fixed to the outer periphery of the emitter fixing member 3 and the emitter portion 1 with a gap therebetween. A heater 11 is provided in the gap and is held by the heat shield plate 10 without contacting the emitter fixing material. Further, an extraction electrode 12 is provided opposite to the emitter portion 1, and a pore 12a is provided in the center of the extraction electrode 12. Further, a ground electrode 13 (cathode) is provided opposite the extraction electrode 12, and a pore 13a is provided in the center thereof coaxially with the pore 12a and the emitter section 1.

A lens barrel for forming an ion probe including a focusing lens, a deflection system, etc., and an exhaust port for evacuating the ion gun chamber 14 are provided below the ground electrode, but are not shown in the figure.

In the ion gun constructed as described above, ampoule 8 containing a reactive metal is inserted into ampoule holder 4 and sealed with cap 9. next,
For example, a heater 11 consisting of a resistance type heater
When the heater 11 is heated by electricity from a heater power source (not shown), the radiant heat generated by the heater 11 and the heat shield plate 11 are
The emitter fixing material 3 is heated by the reflected heat from the emitter, and the heat heats the thermal expansion material 6 by thermal conduction via the thermal expansion material fixing fitting 5. The heated thermal expansion material 6 made of bimetal, for example, begins to curve little by little and comes into contact with one end of the ampoule 8, and the further heated thermal expansion material 6 applies concentrated stress to a part of the ampoule 8, and finally the ampoule 8 curves to the point where it is destroyed. As a result, the sealed liquid metal 2 is filled into the capillary 1a of the emitter section 1, resulting in the state shown in FIG.

Next, the ion beam is generated by energizing the heater 11 to heat the liquid metal filled in the reservoir of the emitter section 1. In this case, the emitter fixing material 3
The emitter section 1 may be heated with separate heaters, or may be heated with the same heater. Alternatively, the capillary 1a of the emitter section 1 may be provided with temperature sensing means to heat the capillary 1a so that the temperature is always constant. Next, an extraction voltage is applied between the emitter part 1 and the extraction electrode 12, and an accelerating voltage is applied between the emitter part 1 and the extraction electrode 13 to form a strong electric field at the tip of the needle 1d. The liquid metal flows out from the gap 1c of the needle 1d due to electrostatic force, reaches its tip from the surface of the needle 1d, and as shown in FIG. This occurs due to the balance between the surface tension of the metal 2 and electrostatic force.

A very large electric field is generated at the tip of the protrusion 2a, and the electric field evaporates and ionizes the metal ions, resulting in an ion beam 16. Ion beam 1 passing through the pore 12a of the extraction electrode 12
6 is further accelerated by the ground electrode 13 and sent through the pore 13a to an ion probe forming column (not shown). The amount of liquid metal loaded into the ampoule 8 can be used semi-permanently, but if the ampoule 8 needs to be reloaded due to an operational error, the cap 9 is removed and the same operation as described above is performed.

Reactive metals that can be used in this invention include:
Examples include cesium, gallium, gold, aluminum, and other metals. In addition, although the above embodiment is applied to a capillary/needle type ion gun, it is applicable to a needle type, capillary type, and other types.
It can be applied to ion guns that generate field ions using EHD, and also to ion guns that use reactive metals as well as EHD.

As described above, according to the present invention, the ampules housed in the ampoule storage space are crushed by the thermal expansion material under vacuum, so that the reactive liquid metal can be safely and reliably released without contacting with air with a simple operation. Can be loaded.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of an ion gun showing an embodiment of the present invention, FIG. 2 is a partially enlarged view thereof, and FIG. 3 is a partially enlarged view showing an operating state. 1: Emitter part, 1a: Capillary, 1
b: spot weld, 1c: gap, 1d: needle, 2: liquid metal, 2a: Taylor cone protrusion,
3: Emitter fixing material, 4: Ampoule holder,
5: Thermal expansion material fixing fitting, 6: Thermal expansion material, 7: Ampoule space, 8: Ampoule, 9: Cap, 10:
Heat shield plate, 11: heater, 12: extraction electrode, 12
a: Pore, 13: Ground electrode, 13a: Pore, 1
4: Ion gun chamber, 15: High voltage introduction terminal, 16: Ion beam.

Claims (1)

[Scope of utility model registration request] A vacuum-evacuated ampoule storage space that stores an ampoule of a reactive metal and communicates with a reservoir portion of the metal, a thermal expansion material for crushing the ampoule, and a means for heating the thermal expansion material. An ion gun characterized by: