JPH0329300A - Strong focussing type charged particle acceleration/ deceleration tube - Google Patents

Abstract

PURPOSE:To accelerate and decelerate ion beams at high efficiency arranging a plurality of electrode couples comprising opposed paired electrodes to overlap each other along the common axis, and applying differential DC voltages to the respective electrode couples in arranged order while arranging the electrode couples orthogonally alternately in the counter direction. CONSTITUTION:A positive ion generated at an ion source 1 is induced by the potential difference between the ion source 1 and an inducing electrode 2 and formed an ion beam B which is led to an acceleration tube A and gradually accelerated along the direction of the common axis (z) through the inside of electrode couples 3, 4... which act as the acceleration electrode. When the positive ion arrives at the overlapped section of the electrode couples 3, 4, the potential of the positive ion becomes the mean between ones of the electrode couples 3,4, and further, when the positive ion arrives at the overlapped section of the electrode couples 4, 5, the potential of the positive ion becomes the means between ones of the electrode couples 4, 5. The beam B in the acceleration tube A is accelerated along the direction of the (z) axis while being focused forcedly along the direction of (x) and (y) axes alternately.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a highly focused charged particle acceleration/deceleration tube for accelerating or decelerating charged particles such as ions and electrons using a direct current voltage. This article relates to an acceleration/deceleration tube suitable for horizontally moving ion beam generators, etc. Conventional technology> Conventionally, in order to accelerate or decelerate a charged particle beam such as an ion beam using a DC voltage, an acceleration/deceleration tube having a hollow cylindrical or circular plate-shaped electrode as shown in Fig. 3 has been used. is used. Note that FIG. 3 shows an example of the configuration of an ion beam generator using this acceleration/deceleration tube as an acceleration tube for accelerating an ion beam, and FIG. 3(a) shows the arrangement of each component. The schematic diagram (b) shows the electrodes 33 (34.
FIG. 35) is an explanatory diagram showing the shape of FIG.

In this configuration example, the ion a31, the extraction electrode 32, and the acceleration tube 30 are arranged along two axial directions, and the acceleration tube 30 has three hollow cylindrical electrodes 33, 34, 35. It is structured by Further, a DC voltage from a high-voltage power supply (not shown) is applied to the ion ag3l and the extraction electrode 32, while a DC voltage from a high-voltage power supply 36 is applied to the electrodes 33, 34, 35 by a series resistor. is applied. Further, at this time, the voltage applied to the electrodes 33, 34, 35 is generally set to become lower as it goes from the electrode 33 located on the extraction electrode 32 side to the electrode 35 on the final stage side. .35 is designed to function as an accelerating electrode.

Therefore, the ions generated in the ion source 31 are extracted in a beam shape by the potential difference between the ions 'a31 and the extraction electrode 32, and then the ions are extracted from the electrode 32 which functions as an accelerating electrode.
, 34.35, it is sequentially accelerated along the z-axis direction. On the other hand, if it is necessary to decelerate the ion beam, the third
By reversing the positive and negative poles of the high-voltage power supply 36 in the configuration example of the ion beam generator shown in the figure, the electrode 33 located on the extraction electrode 32 side is moved from the electrode 35 on the final stage side.
Generally, the higher the DC voltage is applied, the higher the setting is. Then, due to this, the electrodes 33, 34, 35
will function as a deceleration electrode, and the ion 'a3l
The ions generated in the extraction electrode 32 are extracted in a beam shape by the electrodes 33, 34.3, which function as deceleration electrodes.
5, the speed is reduced along two axes.

<Problems to be Solved by the Invention> By the way, in the acceleration/deceleration tube having the above configuration, the major problem is 1! This method has the disadvantage that it is not possible to accelerate or decelerate a flowing ion beam with high efficiency.

The reason for this inconvenience is that the focusing power of the hollow cylindrical ffipi33, 34, 35 is weak, and when accelerating or decelerating a large current ion beam, each part of the beam This is thought to be because the beam diverges along the X-axis and y-axis directions due to the Coulomb force acting between ions. The present invention has been devised in view of these disadvantages, and has a method of accelerating and decelerating a charged particle beam with high efficiency, which has a large focusing power in the process of accelerating and accelerating charged particles using a DC voltage, and which has a large current. IjA can do it!
! The purpose is to provide a bundled charged particle acceleration/deceleration tube.

Means for Solving the Problems> In order to achieve the above objects, the present invention provides two electrodes 3a and 3b, 4a and 4b facing each other, as shown in FIG. 1 corresponding to the embodiment. , . . . while alternately orthogonally intersecting the plurality of electrode pairs 3, 4, .
Each pair of electrodes 3.4. ... is provided with a DC power supply circuit that applies a DC voltage with a potential difference in a predetermined direction according to the arrangement order.

<Function> According to the above precept, each electrode pair 3.4. ... against
By applying a DC voltage with a potential according to the arrangement order on the axis, the charged particles will be accelerated or decelerated along the z-axis direction. At this time, each electrode pair is 3.4
The potential of the charged particles at the overlapping portion of , .
At the b position, the X-axis direction, and at the cross-section c-c position, the y
A force acts to strongly focus the charged particle beam along the axial direction. As a result, this charged particle beam as a whole is accelerated or decelerated along the z-axis direction while each electrode pair 3.4. ... will be focused along the X-axis or y-axis direction.

<Example> Hereinafter, an example of the present invention will be described based on the drawings. Figure 1 shows the configuration of an ion beam generator when the acceleration/deceleration tube according to the present invention is used as an acceleration tube for accelerating a positive ion beam. Schematic structural diagram showing the arrangement state of, Fig. 1(b) ~
(d) is line bb, line cc, and d in Figure 1(a).
- It is a cross-sectional view along the d line. The ion beam generator in this embodiment has ions #l
and an extraction electrode 2 disposed adjacent to the extraction port thereof, and an acceleration tube A is provided on the downstream side of the extraction electrode 2.

A high voltage power source (not shown) is connected to the ion source 1 and the extraction electrode 2, and a DC voltage is applied from this high voltage power source. Accelerator tube A consists of two electrodes (described later) that each face each other. ! Defective electrode pairs, for example, 5 electrode pairs3.
4. 5. 6 and 7 are arranged along the acceleration direction of the ion beam B, that is, along the z-axis direction which is the mutual axis, and each electrode pair 3.4, . . . are perpendicular to each other.

Each of the electrode pairs 3, 4, . . . includes two electrodes 3a and 3b, 4a and 4b, 5a and 5b, . It is constructed by arranging electrodes 6a and 6b and 7a and 7b facing each other around two axes.If the axes that are orthogonal to each other on a plane perpendicular to the z-axis are the X-axis and the y-axis, then the electrodes 3a and 3b , 5a and 5b and 7a and 7b
are opposed along the X-axis direction, and electric currents 4a and 4b and 6a and 6b are opposed along the y-axis direction. Also, at this time, electrode pairs 3 and 4 adjacent to each other along the z-axis direction
, 4 and 5, 5 and 6, and 6 and 7 are overlapped with each other.

Furthermore, the electrode pairs 3, 4,... arranged in this way
A DC power supply circuit S that applies a DC voltage with a potential difference in a predetermined direction according to the arrangement order around C is connected to the high voltage power supply 8 and a resistor R5. After dividing the pressure by ..., each electrode pair 3
, 4,... And electrodes 3, 4 . The voltage applied to each of the electrode pairs 3, 4, . is designed to function as an accelerating electrode. In addition, at this time, each electrode pair 3, 4, .
Two electrodes 3a and 3b . 4a and 4b, . . . are electrically connected and have the same potential. Next, the function and operation of the ion beam generator when the acceleration/deceleration tube according to the present invention is used as the acceleration tube A will be explained. The positive ions generated in the ion source 1 are extracted by the potential difference between the ions St and the extraction electrode 2, and are guided to the acceleration tube A as an ion beam B, thereby forming an electrode pair 3, 4 that functions as an acceleration electrode. , ... are sequentially accelerated along the z-axis direction.

When the positive ions reach the overlapping portion of the electrode pairs 3.4, the potential of the positive ions becomes intermediate between the potentials of the electrode pairs 3 and 4. Therefore, in this overlapping part, see Figure 2 (
As shown in a), when viewed from the ion beam B, the electrodes 3a and 3b that cross the electrode pair 3 are positive, and the electrodes 4a and 4b that cross the electrode pair 4 have a positive potential on the X-axis and y-axis plane. is negative, so a quadrupole horizontal electrode is constructed. Therefore, the ion beam B that has reached these overlapping parts is
It will be strongly focused along the axial direction. Note that at this time, there will be strong divergence along the y-axis direction, but since the focusing force is greater than this divergent force, the combination will result in strong focusing.

Furthermore, when the positive ions reach the overlapping part of the electrode pair 4 and 5, the potential of these positive ions is 1! The potential is midway between the potentials of pole pairs 4 and 5. Then, the X-axis in this overlapping part -
As shown in FIG. 2(b), the potential on the y-axis plane is determined by the potential of the electrodes 4a and 4b forming the electrode pair 4 when viewed from the ion beam B.
is positive, and the electrodes 5a, 5 forming the TF1 pole pair 5
As a result of b becoming negative, the ion beam B that reaches this overlapping portion is strongly focused along the y-axis direction. In this way, the ion beam B is
While being strongly focused alternately along the axial direction and the y-axis direction,
It will be accelerated along the z-axis direction.

In the above description, it is assumed that the positive ion beam is accelerated by the acceleration tube A, but the present invention is not limited to this.
It is also possible to accelerate a negative ion beam by reversing the direction of the potential difference applied to...
It goes without saying that charged particle beams such as electron beams can also be accelerated in a similar manner.

Furthermore, when it is necessary to decelerate the ion beam, the positive and negative poles of the high voltage power supply 8 in the configuration example of the ion beam generator shown in FIG. The setting may be such that a higher DC voltage is applied from electrode pair 3 to electrode pair 7 in the final stage example. That is, by this, electrode pairs 3, 4, 5
．． As a result, the ions generated in the ion source 1 and extracted in the form of a beam by the extraction electrode 2 are transferred to the electrode pair 3 which functions as the deceleration electrode.
, 4, 5.6, and 7, the speed is reduced along two axes.

Effects of the Invention> As explained above, according to the present invention, charged particles are focused along the X-axis direction or y-axis direction at the overlapping portion of each electrode pair, and the charged particles are focused in the z-axis direction as a whole. As a result, even charged particle beams with large currents can be accelerated or decelerated with high efficiency, which is an excellent effect.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 show the configuration of the ion beam generator when the acceleration/deceleration tube according to the present invention is used as an acceleration tube for accelerating a positive ion beam.
FIG. 1(a) is a schematic structural diagram showing the arrangement of each component, and FIGS. 1(b) to 1(d) are lines bb and cc in FIG. 1(a), respectively. It is a cross-sectional view taken along the line dd, and FIG. 2 is a cross-sectional view for explaining the action. Also,
Figure 3 shows an example of the performance of an ion beam generator using a conventional acceleration/deceleration tube as an acceleration tube.
a) is a schematic configuration diagram showing the arrangement of each component;
b) is an explanatory diagram showing the shape of the electrode viewed from the z-axis direction, which is the common axis. In the figure, numeral 1 is an ion source, 2 is an extraction electrode, and 3.
4, 5, 6.7 are electrode pairs, 3a, 3b, 4a, 4b, 5
a, 5b, 6a, 6b, 7a, and 7b are electrodes, 8 is a high-voltage power supply, A is an acceleration tube (acceleration tube), B is an ion beam, R is a resistor, and S is a DC power supply circuit.

Claims (1)

[Claims] (1) A plurality of electrode pairs, each consisting of two electrodes facing each other, are alternately orthogonally crossed in opposite directions, overlapped with each other, and arranged along a common axis, and each electrode pair is arranged in a predetermined manner according to the arrangement order. A strongly focused charged particle acceleration/deceleration tube characterized in that it is provided with a DC power supply circuit that applies a DC voltage with a potential difference in the direction of .