JPS60121659A - Particle analyzer - Google Patents

Abstract

PURPOSE:To check influence of a fringe field on a deflection field by a method, in which when analyzing mass or the like of each particle while deflecting changed particles by an electric field and a magnetic field, the passage of a particle beam to be analyzed to the deflection field is provided with a schielding member. CONSTITUTION:A charged particle beam 2 is incident from an incident port 3 of a vacuum container 1 for being shaped by the collimators 4 and 5 held inside a tublar body 15 made of soft iron or the like provided so as to surround its passage while further being introduced into a magnetic field composed of magnetic poles 6a and 6b for deflecting each particle by 180 deg. following a circular orbit. Next, while being put into an electric field composed of electrodes 7a and 7b for being deflected and incident to a two-dinsional position in the particle detectors 8 to be fixed by mass and energy of each particle. Accordingly, by shielding with the tublar body 15 the orbit can be prevented from being bent due to a fringe field to be generated on the peripheral parts of the respective electrodes 6 and 7 thus improving reliability of measurement.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a particle system in which the II or energy of each particle is analyzed by deflecting charged particles or neutral particles with a deflection field such as an electric field or a magnetic field. Regarding analyzers.

[Technical background of the invention and its problems]

Conventionally, particle analyzers that analyze the mass or energy of charged particles and neutral particles have been used to analyze the above physical quantities by injecting a particle beam into a deflection field such as an electric field or a magnetic field and detecting the amount of deflection of each particle. There are known methods that perform analysis.

Such particle analyzers, for example - charged particle mass energy analyzers for analyzing the mass and energy of charged particles such as H+, D+, are typically constructed as shown in FIGS. 1 and 2. There is. That is, in the figure, reference numeral 1 denotes a vacuum vessel, and the side wall of the vacuum vessel 1 is provided with an input port 3 that is an input port for the charged particle beam 2.

Inside the vacuum container 1, collimators 4 and 5, magnetic poles 6a and 6b, and electrodes 7a and 7b are arranged on the trajectory of the charged particles.

A particle detector 8 is housed in each case. Collimator 4
．． 5, the charged particle beam 2 is made into a predetermined thickness and then shaped into a parallel beam. The magnetic poles 5a and 5b have rectangular magnetic pole faces 9 whose longitudinal direction is the vertical direction in FIG.
a and 9b, and these magnetic pole faces 9a and 9b are arranged to face each other with a predetermined gap in between. These magnetic poles 5a and 6b generate a magnetic field in a direction perpendicular to the plane of the paper in FIG. 1 by energizing coils 10a and 10b wound around them, respectively.

Further, the electrodes 7a and 7b are made of trapezoidal plates whose width increases from the top to the bottom in FIG.
The magnetic pole surface 9
a and 9b and are arranged to face each other in parallel, and generate an electric field in the same direction as the magnetic field. In addition, numeral 11 in the figure is an exhaust port leading to a pump (not shown) that exhausts the gas P in the vacuum container 1.

In the charged particle mass energy analyzer configured in this manner, the charged particle beam 2 introduced into the vacuum vessel 1 from the input boat 3 is shaped into a parallel beam by the collimators 4 and 5, and is shaped into a parallel beam by the collimators 4 and 5. It is introduced into the magnetic field generated by M6a and M6b.

Each particle of the charged particle beam 2 introduced into the magnetic field receives a force in a direction perpendicular to the direction of movement of the particle and the direction of the magnetic field,
It is deflected 180° following a circular trajectory.

At this time, the radius of motion of each particle is determined by the kinetic energy of each particle. Therefore, each particle oriented in the 1806 pan is distributed on a straight line at a position corresponding to the kinetic energy at the end of the magnetic field.

Each charged particle that has passed through the magnetic field is further deflected in the direction of the electric field by being introduced into the electric field generated by the electrodes 7a, 7b. The amount of deflection of each particle at this time is determined by the mass of each particle.

Thus, each particle is incident on the particle detector 8 at a two-dimensional position determined by the mass and energy of each particle, and the mass and energy of each particle are detected here.

By the way, in such a charged particle mass energy analyzer, between the magnetic poles 6a and 6b or between the electrode 7a.

Ideally, the magnetic flux and electric flux generated between 7b are all in the same direction, but in reality, there is a so-called fringe field in which the magnetic flux or electric flux curves outward at each peripheral edge. Existing. Therefore, particles with low energy that have passed through the collimators 4 and 5 are influenced by the fringe field before being introduced into the magnetic field, and their trajectory is slightly bent as shown by Q in the figure. Put it away. Such a deviation in the trajectory is amplified to a non-negligible extent in the vicinity of the particle detector 8, so in conventional particle analyzers of this type, the trajectory of the particle beam is determined by taking into account the influence of the fringe field. It needed to be fixed. However, since the influence of such fringe fields on charged particles is a problem involving various complex factors, it cannot be easily predicted. There were problems such as slippage.

[Purpose of the invention]

The present invention has been made in consideration of these circumstances, and its purpose is to suppress the influence of fringe fields of charged particles, thereby eliminating the need for adjustments to correct the trajectory of particle beams and making it easier to use. The object of the present invention is to provide a particle analyzer that is easy to use and highly reliable.

[Summary of the invention]

The present invention is characterized in that a member of the seal 1 for blocking the influence of the deflection field is provided in close proximity to the path of the particle beam that reaches the deflection field such as an electric field or a magnetic field.

〔Effect of the invention〕

With such a configuration, the path of the particle beam to the diagonal field is magnetically or electrostatically shielded, making it less susceptible to the effects of the fringe field. Therefore, the trajectory of the particle beam to be analyzed along the above path can be stabilized magnetically or electrostatically, and as a result, the reliability of measurements can be improved and adjustment work that was previously required. This has the advantage that it can be omitted.

(Example of the invention) Hereinafter, details of the present invention will be explained based on illustrated embodiments.

FIG. 3 shows an embodiment in which the present invention is applied to a charged particle mass energy analyzer, and the same parts as in FIG. 1 are designated by the same reference numerals. Therefore, we will omit the explanation of the redundant parts.

This embodiment differs from conventional analyzers in that the vacuum vessel 1
A cylindrical body 15 surrounds the path of the charged particle beam 2 from the entrance port 3 in the interior to just before the entrance ends of the magnetic poles 6a and 6b.
This is because we have established This cylindrical body 15 is made of, for example, soft iron, and exhibits the magnetic sealing effect 1~ inside the cylindrical body 15 and the electrostatic shielding effect. Collimators 4.5 are arranged inside the cylindrical body 15 at predetermined intervals in the traveling direction of the charged particle beam 2. In addition, 16.17 in FIG. 3 indicates the gas inside the space surrounded by the cylindrical body 15, the input port 1-3, and the collimator 4, and the gas inside the space surrounded by the cylindrical body 15, the collimator 4, and the collimator 5. These holes are for exhausting the gas inside the space to the outside of the container 1 through the vacuum container 1, respectively.

With such a configuration, the magnetic ti6a from the collimator 5
, 6b will be electromagnetically and electrostatically shielded, so that even charged particles with low energy will have stable trajectories. Therefore, according to this embodiment, the reliability of measurement is improved, and the effort of adjusting the analyzer in advance in consideration of the influence of the fringe field on charged particles can be saved. I can do it. Moreover, in this case, the cylindrical body 15 made of a shielding member is provided at a specific location within the vacuum container 1. Since the structure is extremely simple, the analyzer as a whole does not become complicated.

Note that the present invention is not limited to the above embodiments,
For example, as shown in FIG. 4, the collimator 5 and the magnetic pole 5a,
5b and the path of the charged particle beam 2 between the electrodes 7a, 7
A plate member 20 made of an electrostatic shielding material such as aluminum may be provided between the member and the member b. Even with such a simple configuration, the path of the charged particle beam 2 electrostatically blocks the fringe field generated at the electrodes 7a and 7b, so it is possible to stabilize the motion trajectory of the charged particles. can. Further, the above path may be shielded only magnetically.

Although the above example is an example in which the present invention is applied to a charged particle mass energy analyzer, the present invention can also be applied to a neutral particle analyzer in which a charge exchange cell is installed at the location where the collimator 4.5 is installed. Applicable.

It goes without saying that the present invention is applicable not only to particle mass energy analyzers, but also to particle energy analyzers in which only a magnetic field is formed in a vacuum container, and particle mass analyzers in which only an electric field is formed in a vacuum container. stomach.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view showing a conventional multiparticle mass energy analyzer, and Figure 2 is a cross-sectional view of the charged particle mass energy analyzer taken along line A-A in Figure 1 and viewed in the direction of the arrow. 3 is a schematic sectional view showing a charged particle mass energy analyzer according to an embodiment of the present invention, and FIG. 4 is a schematic cross-sectional view showing a charged particle mass energy analyzer according to another embodiment of the present invention. FIG. 1... Vacuum vessel, 2... Loaded particle beam, 3...
Input boat, 4, 5...Collimator, 6a, 6b...
・Magnetic pole, 7 a, 7 b -71 pole, 8...Particle detector, 9a, 9b...Magnetic surface, 10a, 10b...
・Coil, 11...Exhaust port, 15...Between 4j (body,
16.17...hole, 20...plate. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] Deflect the particle beam to be analyzed using a deflection field such as an electric field or a magnetic field,
In a particle analyzer that analyzes the mass or energy of each particle constituting the beam by detecting the amount of deflection, the particle analyzer is configured to analyze the mass or energy of each particle constituting the beam by detecting the amount of deflection. A particle analyzer characterized by being provided with a shield member that blocks the influence of fringe fields.