JPH0616110B2 - Neutral particle mass energy analyzer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a mass energy analyzer for analyzing the mass and energy of neutral particles generated from a nuclear fusion device.

(Prior Art) FIG. 1 is a block diagram of a conventional neutral particle mass energy analyzer. A stripping cell 2 is provided in a vacuum vessel 1 directly connected to a fusion device (not shown) by a vacuum joint.
A deflection electromagnet 3, an electrostatic deflection plate 4 and a particle detector 5 are installed. The stripping cell 2 has a function to charge-exchange the incident neutral particles 6 with a neutral gas stored in the cell and ionize the neutral particles 6 to change them into incident ions. The deflecting electromagnet 3 has a function of causing the injected ions to undergo Larmor motion.

Therefore, the incident ions passing through the deflecting electromagnet 3 make circular motions having different radii of rotation according to the energy of the incident ions. That is, the deflecting electromagnet 3 has a function of discriminating the momentum of incident ions. The electrostatic deflection plate 4 has a function of displacing in a direction perpendicular to the paper surface by applying an electric field to incident ions after the end of the Larmor motion due to the difference in mass.

In this way, the incident ions deflected with different displacements due to the difference between mass and energy are detected by the position detection type particle detector 5 installed behind the electrostatic deflection plate 4 depending on the arrival position. And are detected.

When the coordinate axes x, y and z are defined in the directions shown in the figure, the incident neutral particle 6 causes the Rama motion by the magnetic field B used in the z direction of the deflecting electromagnet 3, and its traveling direction is 18
Rotate 0 degrees. If the rotation diameter at this time is X, Becomes

However, m is the mass of the neutral particles, V is the velocity, q is the charge amount,
B is a magnetic field.

Next, by the electric field applied in the z direction in the electrostatic deflection plate 4,
Incident ions are applied in the z direction. If the displacement in the z direction detected by the particle detector 5 is Z, Becomes Here, 1 is a passage electrode length of incident ions passing through the electrostatic deflector 4, l'is a distance between the component deflector 4 and the particle detector 5, and E is an electric field of the electrostatic deflector 4.

The path of the incident neutral particles 6 traveling through the stripping cell 2 is f, one side of the electrostatic deflector 4 on the particle incident side is j, and the intersection of this path f and one side j is 0. Then, as shown in FIG. 1, if the extension line h of the particle detector 5 and the extension line of the rear end side i of the electrostatic deflection plate 4 pass through the intersection point 0, the particle detector 5 The displacement of incident ions in the z direction at a position is the same for particles having different momentums if the mass is the same.

Therefore, in the conventional energy analyzer, the electrostatic deflection plate 4 has a trapezoidal shape as shown in FIG.

(Problems to be Solved by the Invention) FIG. 2 is a view showing a cross-sectional structure of the electrostatic deflection plate 4 when cut along the line AA ′ shown in FIG. When attempting to perform mass energy analysis of incident neutral particles over a wide range from high energy to low energy, in the conventional analyzer, the electrode length l at which the particles pass through the electrostatic deflector 4 is particularly low on the low energy side. When the distance is smaller than the distance Δ, there is a problem that particles are changed from passing through the orbit I to the orbit II due to the effect of the leakage electric field as shown in FIG. For this reason, on the low energy side, the displacement in the Z direction at the detection position of the particle detector 5 becomes large, so that there is a disadvantage that detection cannot be performed when the roof is detected or a detection result with a large error is displayed.

An object of the present invention is to provide a neutral particle mass energy analyzer capable of sufficiently measuring even low-energy neutral particles.

[Structure of Invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention has a stripping cell that ionizes incident neutral particles to make incident ions, and a magnetic field is applied to the incident ions to cause Larmor motion. And a deflection electromagnet for rotating the advancing direction of the incident ion by 180 degrees with a different radius of rotation depending on the energy of the incident ion, and an electric field is applied to the incident ion after the end of the Larmor motion to change the mass of the incident ion. And an electrostatic deflector for deflecting the traveling direction with different displacements, and a particle detector installed behind the electrostatic deflector so as to detect the energy and mass of the incident ions depending on their arrival positions. In the apparatus for analyzing the mass energy of neutral particles, an accelerating electron for accelerating the traveling speed of the incident ions between the deflection electromagnet and the electrostatic deflection plate. It is characterized in that the electrostatic deflector is provided with poles, the ion-passing electrode length l is substantially given by the following equation, and is sufficiently longer than the deflector spacing.

(However, l '... distance between the electrostatic deflection plates and the particle detector, q ... charge amount, electric field E 2 _... electrostatic deflection plate, Z-direction displacement amount in the Z 0 _... microchannel plate detector , U ₀ ... Potential energy obtained by incident ions by the accelerating electrode, B ... Magnetic field by the deflection electromagnet, x ... Larmor diameter, m ... Mass of neutral particles) (Function) The mass energy analyzer for neutral particles according to the present invention, Energy is given to the ionized neutral particles by the acceleration electrode provided between the displacement electromagnet and the electrostatic deflection plate, and the ion passage electrode length of the electrostatic deflection plate through which the ions pass is made sufficiently longer than the distance between the deflection plates to make it static. The influence of the leakage electric field of the electric deflection plate is eliminated.

(Embodiment of the Invention) An embodiment of the present invention will be described in detail below with reference to FIGS. 3 and 4.

The same parts as those shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. FIG. 3 is a block diagram showing an embodiment of the present invention, and FIG. 4 is a sectional view of a portion cut along the line BB 'shown in FIG. Compared with the conventional device shown in FIG. 1, in the embodiment shown in FIG. 3, an accelerating electrode 7 for accelerating the traveling speed of incident ions is provided between the deflecting electromagnet 3 and the electrostatic deflecting plate 4a. It has been newly added. Assuming that the potential energy obtained by the accelerating electrode 7 by the incident ions is U ₀ and the displacement in the Z direction at the particle detector 5 is Z ₀ , the ion passing through the electrostatic deflection plate 4a when the initial velocity of the incident ions is V ₀ The electrode length l is given by the following equation.

However, l 'is the distance between the electrostatic deflection plates 4a and particle detector 5, x is Rama diameter, E ₂ is the electric field between the electrostatic deflection plates 4a. When the incident ion energy is small (3)
ceremony, Becomes In the conventional apparatus as shown in FIG. 1, since the acceleration electrode 7 does not exist, U ₀ = 0 and therefore the ion passage electrode length 1 becomes 0, but in the embodiment shown in FIG. 3, U ₀ > 0. If U ₀ is sufficiently large, the ion passing electrode length l will be The size is proportional to. Therefore, if the potential energy U ₀ is given so as to satisfy l> Δ, it is possible to eliminate the deviation of the trajectory of the incident ions due to the influence of the leakage electric field of the electrostatic deflection plate 4a.

〔The invention's effect〕

As described in detail based on the above embodiments, in the present invention, by using an accelerating electrode, energy is given to ionized neutral particles, and further, the length of the ion passing electrode of the electrostatic deflecting plate through which the ions pass is set to the deflecting plate. Since the distance is made sufficiently longer than the distance, the influence of the electric field of leakage of the electrostatic deflection plate can be eliminated. Therefore, low-energy neutral particles can be measured sufficiently accurately.

[Brief description of drawings]

FIG. 1 is a block diagram of a conventional mass energy analyzer, FIG. 2 is a sectional view taken along the line AA ′ in FIG. 1, and FIG. 3 is a block diagram showing an embodiment of the present invention. FIG. 4 is a sectional view taken along the line BB ′ in FIG. 2 ... Stripping cell, 3 ... Bending electromagnet, 4a ...
... Electrostatic deflector, 5 ... Particle detector, 6 ... Neutral particles, 7
…… Accelerating electrode.

Claims (1)

[Claims] 1. A stripping cell for ionizing incident neutral particles into incident ions, and a magnetic field applied to the incident ions to cause Larmor motion to cause the incident ions with different radii of rotation depending on the energy of the incident ions. A deflection electromagnet that rotates the advancing direction of the ions by 180 degrees, an electrostatic deflection plate that applies an electric field to the incident ions after the end of the Larmor motion, and deflects the advancing directions with different displacements according to the mass of the incident ions, and the incidence. A neutral particle mass energy analyzer comprising a particle detector installed behind the electrostatic deflection plate so as to detect the energy and mass of the ion depending on the arrival location of the ion, in the neutral particle mass energy analyzer. An accelerating electrode for accelerating the advancing velocity of the incident ions is provided between the electrode and the electro-deflecting plate, and the ion-passing electrode length l has a shape given by the following equation. One deflector mass energy spectrometer neutral particles, characterized in than that with sufficiently lengthened the electrostatic deflection plates intervals. (However, l '... distance between the electrostatic deflection plates and the particle detector, q ... charge amount, electric field E 2 _... electrostatic deflection plate, Z-direction displacement amount in the Z 0 _... microchannel plate detector , U ₀ ... potential energy obtained by the incident ions by the accelerating electrode, B ... magnetic field by the deflection electromagnet, X ... Larmor diameter, m ... mass of neutral particles)