JP2627420B2 - Fast atom beam source - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-speed atomic beam source that efficiently emits a high-speed atomic beam.

[Conventional technology]

An atom that is thermally moving in the normal temperature atmosphere has a kinetic energy of about 0.05 eV. Atoms that fly with much higher kinetic energy than this are called "fast atoms", and when they flow in a beam in one direction, they are called "fast atom beams".

FIG. 1 shows an example of a conventionally proposed high-speed atomic beam source that emits argon atoms having a kinetic energy of 0.5 to 10 KeV among the conventional sources for generating high-speed atomic beams of gas atoms.
In the figure, 1 is a cylindrical cathode, 2 is a donut-shaped anode, 3 is
0.5 to 10 KV DC high-voltage power supply, 4 is a gas introduction hole, 5 is an argon gas, 6 is a plasma, 7 is a fast atom beam emission hole, 8
Is a fast atom beam.

In such a configuration, components other than the DC high-voltage power supply 3 are housed in a vacuum vessel, and after sufficiently exhausting, an argon gas 5 is injected into the inside of the cylindrical cathode 1 from the gas introduction hole 4. Here, the anode 2 has a positive potential by the DC high-voltage power supply 3,
A high DC voltage is applied so that the cathode 1 has a negative potential. As a result, a glow discharge occurs between the cathode 1 and the anode 2, and plasma 6 is generated, and argon ions and electrons are generated.
Further, in this discharge, electrons emitted from the bottom surface of the cylindrical cathode 1 are accelerated toward the anode 2 and pass through the central hole of the anode 2 to reach the bottom surface on the opposite side of the cylindrical cathode 1 where the velocity is increased. , And starts to be accelerated again toward the anode 2. Thus, the electrons vibrate at a high frequency between the two bottom surfaces of the cylindrical cathode 1 through the central hole of the anode 2, and collide with the argon gas during that time to generate a large number of argon ions. The argon ions thus generated are accelerated toward the bottom surface of the cylindrical cathode 1 to obtain sufficient kinetic energy. This kinetic energy is about 1 kV when the discharge sustaining voltage between the anode 2 and the cathode 1 is about 1 KV, for example.
It is about KeV. The space in the vicinity of the bottom surface of the cylindrical cathode 1 is a turning point of electrons that vibrate at a high frequency and is a space where many low-energy electrons are present. Argon ions that have entered this space recombine with electrons and return to argon atoms. In the collision between the ion and the electron, the mass of the electron is negligibly smaller than that of the argon ion, so that the kinetic energy of the argon ion is inherited by the atom without any loss and becomes a fast atom. Some of the argon ions that have entered the space near the bottom surface of the cylindrical cathode 1 lose contact with the argon gas floating in the space and return to neutral argon atoms. Since the contact between the ions and the argon gas is not so severe as to change the kinetic energy, the kinetic energy of the ions is passed on to the neutral atoms as they are, and high-speed argon atoms are generated. Therefore, the kinetic energy of the fast atom in these cases is about 1 KeV. These fast atoms are emitted as fast atom beams 8 from emission holes 71 formed in one bottom surface of the cylindrical cathode 1.

[Problems to be solved by the invention]

However, in the conventional high-speed electron beam source, the ions (residual ions) that failed to become the fast atoms are emitted from the fast atom beam emission hole 7 together with the fast atoms. In order to remove the fast atoms and remove only the fast atoms, a method of installing a deflector after the fast atom beam emission hole 7 and applying a high DC voltage to the deflector is required, and a DC voltage power supply is required. In addition, there was a point that it was unusable in consideration of insulation for applying high voltage.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a compact high-speed atomic beam source that efficiently emits a high-speed atomic beam having any energy from low energy to high energy. Is provided.

[Means for solving the problem]

A fast atom beam source according to the present invention comprises a cylindrical cathode having a beam emission hole on the side of a cylinder, and a cylindrical ion block disposed concentrically outside the cylindrical cathode and having a fast atom emission hole on the side of the cylinder. It has an electrode structure consisting of an electrode and a rod-shaped anode disposed inside the cylindrical cathode and parallel to the central axis of the cylindrical cathode, and has a beam emission hole of the cylindrical cathode, and a cylindrical ion block. A fast atom emission hole of the electrode and a rod-shaped anode are arranged side by side on the same line, and a DC high-voltage power supply for discharge is connected between the cylindrical cathode and the rod-shaped anode to form a rod-shaped anode and a cylindrical ion-blocking electrode. Are maintained at the same potential, and a magnet for applying a magnetic field substantially parallel to the central axis of the cylinder is provided between the cylindrical cathode and the cylindrical ion blocking electrode.

[Action]

In the present invention, the residual ion electrons are removed by a blocking electric field for ions applied between a cylindrical cathode having an emission hole and a cylindrical ion blocking electrode and a deflection magnetic field for electrons. In addition to the need for a DC high-voltage power supply for driving the deflector, there is no need to consider insulation for applying a high voltage.

〔Example〕

FIG. 1 is a partially cutaway configuration view showing an embodiment of an ion neutralizer according to the present invention. In the figure, 21 is a cylindrical cathode made of pure iron, 22 is a bar-shaped anode, 23 is a ring-shaped permanent magnet, 24
Is a magnetic field, 25 is a negative DC high voltage power supply, 26 is a beam emission hole, 27
Is a cylindrical ion blocking electrode, 28 is a high-speed electron beam emission hole, 29
Is a mixed beam of fast atoms and ions, 30 is a fast atom beam,
Reference numeral 31 denotes a gas introduction hole, and the interval between the cylindrical cathode 21 and the rod-shaped anode 22 is set to be much smaller than the interval between the cylindrical cathode 21 and the ion blocking electrode 27. The rod-like anode 22, the beam emission hole 26, and the fast atom beam emission hole 28 are arranged so as to be aligned on the same line. A negative DC high voltage is applied to the cylindrical cathode 21 by a power supply 25. The rod-shaped anode 22 and the ion blocking electrode 27 are kept at the same potential. Also, since the cylindrical cathode 21 is made of pure iron, the magnetic field
Is the cylindrical cathode without entering the space inside the cylindrical cathode 21.
The voltage is applied only to the space between the cylindrical cathode 21 and the ion blocking electrode 27 in parallel with the central axis of 21. In addition, components other than the power supply 25 are housed in a vacuum vessel and sufficiently exhausted,
For example, oxygen gas is injected into the inside of the cylindrical cathode 21 from outside the vacuum vessel through the gas introduction hole 31.

In such a configuration, the rod-shaped anode 22 is
A glow discharge is generated between the cathode and the cylindrical cathode 21 to generate a large amount of oxygen ions. On the other hand, the interval between the cylindrical cathode 21 and the ion blocking electrode 27 is set to be much wider than the interval between the cylindrical cathode 21 and the rod-shaped anode 22, so that no discharge occurs during this interval. The generated oxygen ions are accelerated toward the cylindrical cathode 21, and when they reach the vicinity of the cylindrical cathode 21, sufficient kinetic energy is obtained. Oxygen ions that have obtained sufficient kinetic energy come into contact with oxygen gas drifting in the vicinity of the cylindrical cathode 21 to lose charge and return to neutral oxygen atoms. The contact between oxygen ions and oxygen gas
The kinetic energy of the oxygen ions is passed on to the neutral atoms as they are, not so intense as to change the kinetic energy.
At 29, the light is emitted from the beam emission hole 26 toward the ion blocking electrode 27. The beam 29 contains not only fast atoms but also ions (residual ions) that failed to become fast atoms. Since the potential of the ion blocking electrode 27 is maintained at the same potential as the rod-shaped anode 22, an electric field is applied to the space between the cylindrical cathode 21 and the ion blocking electrode 27 in a direction to block the movement of the residual ions. You will have. Beam 29
The residual ions mixed into the ion gradually lose energy, and when reaching the ion blocking electrode 27, the velocity becomes almost zero and cannot be emitted out of the fast atom beam emission hole 28. Only fast atoms will be released.
This is the fast atomic beam 30. Also, some of the fast atoms and residual ions that have exited the beam emission holes 26 collide with the residual gas floating in this space and ionize them, generating ions and electrons. Due to the electric field between the cylindrical cathode 21 and the ion blocking electrode 27, ions are accelerated in the direction of the cylindrical cathode 21 and electrons are accelerated in the direction of the ion blocking electrode 27. Fast atom emission holes 28 mixed with fast atoms 30
Concerns that are released from However, in the space between the cylindrical cathode 21 and the ion blocking electrode 27, since the magnetic field 24 and the electric field are applied at right angles, the electrons draw a circular orbit without going straight, and the fast atom emission holes 28 Can not be released from Even if electrons emitted from the fast atom emission holes 28 are collected, they do not enter the fast atom beam 30 because the motion direction is greatly different from the emission direction of the fast atom beam 30.

If the gas introduced through the gas introduction hole 31 is argon, a high-speed electron beam of argon is emitted. Further, the magnet 23 may be an electromagnet. Further, the cylindrical cathode 21 need not be pure iron, but may be any conductive material having high magnetic permeability.

Further, the dose of the emitted fast atomic beam 30 can be adjusted by the amount of gas to be injected. The kinetic energy of the fast atomic beam 30 can be set to a predetermined value by adjusting the voltage of the high-voltage power supply 25.

〔The invention's effect〕

As described above, according to the present invention, it is not necessary to use a deflector for obtaining a pure high-speed atomic beam by removing residual ions. The operability is also improved at the same time as the consideration of insulation against voltage is not required. Also,
When high-speed ions or atoms collide with a solid, spatter is generated on the surface of the solid, and secondary atoms, secondary ions, and light are emitted. It is well known that these phenomena are used for processing and analysis. However, when the solid is an insulator, it is charged by the collision of ions, and the incidence of subsequent ions is obstructed, so that processing and analysis do not proceed. On the other hand, such a phenomenon is caused by the impact of electrically neutral atoms. There is a remarkable difference that processing and analysis can be performed without delay. In this sense, the small high-speed atomic beam source according to the present invention has excellent effects such as extremely high utility.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a fast atom beam source according to one embodiment of the present invention, and FIG. 2 is a diagram showing a configuration of a conventional fast atom beam source. 21: Pure iron cylindrical cathode, 22: Rod anode, 23: Permanent magnet, 24: Magnetic field, 25: Negative DC high voltage power supply, 26 ...
Beam emission hole, 27: ion blocking electrode, 28: fast atom beam emission hole, 29: mixed beam of fast atoms and ions, 30
…… High-speed atomic beam, 31 …… Gas inlet.

Claims (1)

(57) [Claims] A cylindrical cathode having a beam emission hole on a side surface of a cylinder; a cylindrical ion blocking electrode disposed concentrically outside the cylindrical cathode and having a fast atom emission hole on the side surface of the cylinder; An electrode structure consisting of a rod-shaped anode disposed inside the cylindrical cathode and parallel to the central axis of the cylindrical cathode, a beam emission hole of the cylindrical cathode, and fast atom emission of the cylindrical ion blocking electrode The hole and the rod-shaped electrode are arranged on the same line, a DC high-voltage power supply is connected between the cylindrical cathode and the rod-shaped anode, and the rod-shaped anode and the cylindrical ion-blocking electrode are held at the same potential, A high-speed atom beam source, wherein a magnet for applying a magnetic field is provided in a space between the cylindrical cathode and the cylindrical ion blocking electrode substantially in parallel with a central axis of the cylinder.