JPS6259857B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a particle detection device capable of measuring the energy, mass, spatial distribution, etc. of charged particles.

In order to analyze or control the characteristics of plasma generated by plasma generators generally used in nuclear fusion reactors, etc., it is necessary to measure the energy, particle type, spatial distribution, etc. of particles emitted from the plasma generator. There is a need. Conventionally, particle detection devices such as those shown in FIGS. 1 and 2 have been used to measure such particles. That is, 1a,
1b is a pair of magnetic poles, these magnetic poles 1a,
The structure is such that a uniform magnetic field is formed between the parts 1b. Reference numerals 2a and 2b are a pair of electrodes, and the structure is such that an electric field is formed between these electrodes 2a and 2b, parallel to and overlapping with the magnetic field. And these magnetic poles 1a, 1b
One side edge of the electrodes 2a and 2b is formed in a straight line, so that the boundaries on one side of the generated magnetic field and electric field are straight. Reference numeral 3 denotes a collimator, which has a slit 4 for regulating the direction of particles, and is configured to allow external particles to enter the magnetic and electric fields from one side in a direction perpendicular to them. Furthermore, 5a and 5b are a plurality of particle detectors, for example, two particles. Each of these particle detectors 5a, 5b is constructed by linearly arranging small electron multiplier type particle detectors 6, and includes the magnetic poles 1a, 1b and the electrodes 2a,
2b, and are arranged along a direction in which their longitudinal directions are orthogonal to the magnetic field and the electric field. Further, these particle detectors 5a and 5b are arranged at positions offset from the collimator 3 by a predetermined distance in a direction parallel to the magnetic field and the electric field. Of the particles incident through the slit 4 of the collimator 3, charged particles such as H ⁺ , D ⁺ and He ⁺ enter the magnetic field and the electric field in a direction perpendicular to these. Due to the magnetic field, the incident charged particles draw semicircular trajectories as shown in Figure 1.
It is deflected by the electric field and displaced in the direction of the electric field as shown in FIG.
a, 5b. The amount of displacement in the direction of this electric field is determined by the ratio of the charge to the mass of the charged particle, and since this ratio is constant depending on the type of charged particle, the strength of the electric and magnetic fields must be determined in advance. For example, the amount of displacement for each charged particle is determined.
Therefore, if the particle detectors 5a and 5b are arranged as described above at positions corresponding to the displacement of the charged particles to be measured, it is possible to determine which particle detectors 5a and 5b the charged particle has entered. The type of charged particle can be determined by Furthermore, the radius of the semicircular locus drawn by a charged particle is determined by the product of the mass and energy of the charged particle. Depending on which particle detector 6 of the particle detectors 5a, 5b this charged particle enters, the charged particle is transmitted from the slit 4 of the collimator 3 to the particle detector 5a, 5b.
Since the incident position, that is, the diameter of the semicircular trajectory, is known, if the strength of the magnetic and electric fields is known in advance, the mass and energy of the charged particle can be calculated depending on which particle detector 6 the charged particle is incident on. The product becomes clear.
As mentioned above, the type of charged particle, that is, the mass, can be determined by the amount of displacement in the direction of the electric field.
The energy of the charged particles can also be determined. Incidentally, in such a particle detection device, the length of the particle detection bodies 5a and 5b is at least 2 times the maximum radius of the semicircular locus drawn by the charged particles.
It has to be doubled. Therefore, if a plurality of collimators 3 are provided to determine the spatial distribution of particles, the spacing between the collimators 3 must be at least twice the maximum radius mentioned above, and the spacing should not be smaller than this. Then, it becomes impossible to determine from which collimator 3 the charged particles incident on the particle detector 6 including the particle detectors 5a and 5b are incident, and measurement becomes impossible. For this reason, in the conventional model, the distance between the collimators 3 has to be increased,
It was not possible to precisely measure the spatial distribution of charged particles. Conventionally, in order to solve this problem, a plurality of particle detection devices have been stacked one on top of the other so that their collimators are slightly shifted from each other. This increases the overall size and makes it impossible to insert into narrow spaces, making it difficult to access the measurement target.
In addition, the power consumption of the magnet that generates the magnetic field becomes large, and a preamplifier, amplifier, etc. must also be provided for each particle detection device, resulting in a problem that the signal processing system becomes complicated.

The present invention was made based on the above circumstances, and its purpose is to be able to arrange the slits into which particles enter at small intervals, to accurately measure the spatial distribution of particles, and to make the entire structure compact. ,
The object is to obtain a particle detection device that can be simplified.

The present invention will be explained below with reference to an embodiment shown in FIGS. 3 to 5. 101a, 101 in the figure
b is a pair of magnetic poles, these magnetic poles 101
a and 101b face each other with a predetermined interval. And these magnetic poles 101a, 101b
A uniform magnetic field of a predetermined strength is formed in the gap between the two by a magnet (not shown). Further, 102a and 102b are a pair of electrodes, and these electrodes 102a and 102b are housed in the gap between the magnetic poles 101a and 101b. A predetermined voltage is applied between these electrodes 102a, 102b, and these electrodes 102a,
It is configured such that electric fields are formed between the magnetic fields 102b that are parallel to the magnetic field and overlap each other.
One side edges of these magnetic poles 101a, 101b and electrodes 102a, 102b are formed in a straight line, so that the boundary on one side of the generated magnetic field and electric field is straight. Also, 103
a, 103b, 103c... are collimators, and a plurality of collimators are arranged at relatively small intervals in the direction along one side edge of the magnetic poles 101a, 101b and the electrodes 102a, 102b. And these collimators 103a, 103b, 103c
... is a slit 10 that regulates the direction of incidence of charged particles
4... and passed through these slits 104...
Charged particles such as H ⁺ and D ⁺ are located at the magnetic poles 101a and 10.
1b and the magnetic field and electric field formed in the gap between the electrodes 102a and 102b in a direction perpendicular to these fields. Also, 1
05a and 105b are position-sensitive particle detectors. These position-sensitive particle detectors 105a, 10
5b has an elongated shape, and its longitudinal direction is the magnetic pole 101.
a, 101b and along one side edge of the electrodes 102a, 102b. These position-sensitive particle detectors 105a, 105b are provided to be displaced relative to the collimators 103a, 103b, 103c, etc. in accordance with the amount by which charged particles to be measured are displaced in the direction of the electric field within the electric field. , for example, D ⁺ particles are sent to the position-sensitive particle detector 105a, and H ⁺
The particles are configured to respectively enter the position-sensitive particle detectors 105b. The position-sensitive particle detectors 105a, 105b are the product of the incident position y of the charged particle in the longitudinal direction, that is, along one side edge of the magnetic poles 101a, 101b and the electrodes 102a, 102b, and the energy k of the charged particle. It is capable of determining k.y and energy k, and its configuration will be explained below with reference to FIG. 5. This position-sensitive particle detector 105a, 10
5b is a device using a semiconductor, and 106 is its substrate. An n-side electrode 107 and a p-side electrode 108 are adhered to both sides of this substrate 106, and the n-side electrode 107 has a sufficiently small electrical resistance, and the p-side electrode 108 has a predetermined electrical resistance per unit length. have. And the n-side electrode 107
A terminal 109 is provided at one end of the terminal 10.
9 is connected to a power supply via a predetermined resistor 110 and to a signal processing circuit 112 via a preamplifier 111. In addition, the p-side electrode 1
08 are provided with terminals 113 and 114, respectively, one terminal 113 is connected to a signal processing circuit 112 via a preamplifier 115, and the other terminal 114 is connected to the ground side. These position-sensitive particle detectors 105a and 105b
When a charged particle is incident at the position indicated by the arrow A, which is y apart from the other end, electrons in the full band of the semiconductor at this incident position are excited and pumped up into the conduction band, and at this incident position, the electrons are transferred from the n-side electrode 107 to the p A pulsed current Io flows through the side electrode 108, and the pulse height of this current Io is proportional to the energy k of the incident charged particle. Since the n-side electrode 107 has a sufficiently low electrical resistance, this n-side electrode 107
Since the pulse height of the current flowing through the terminal 109 of the n-side electrode 107 is equal to the current Io flowing at the incident position of the charged particle regardless of the incident position of the charged particle, by detecting the current flowing through the terminal 109 of the n-side electrode 107, The energy k of the incident charged particle is then determined. Further, this current Io is divided into a current I ₁ directed toward one terminal 113 and a current I ₂ directed toward the other terminal 114 at the p-side electrode 108 . The ratio of these currents I ₁ and I ₂ is determined by the ratio of resistances from the charged particle incident position to the respective terminals 113 and 114. Since this p-side electrode 108 has a predetermined electrical resistance per unit length, each of the terminals 113, 114 from the incident position
The electrical resistance from the incident position to each terminal 1
It is proportional to the distance to 13,114. Therefore, the effective length of the position-sensitive particle detectors 105a and 105b, that is, the distance between the terminals 113 and 114, is
y ₀ , the distance from the incident position to one electrode 113 is
y ₁ and the distance from the incident position to the other electrode 114 is y, the current I ₁ flowing through one terminal 113 is I ₁ =I ₀ ×y/y ₀ (1). Therefore, by detecting this current I ₁ , the product k·y of the energy k of the incident charged particle and the distance y from the other end to the incident position can be determined.

In one embodiment of the present invention configured as described above, the charged particles are e.g.
04 into the magnetic and electric fields. Then, a semicircular trajectory T with radius r is drawn by the magnetic field.
The position-sensitive particle detector 105 is deflected by 180° and is also displaced by the electric field by z in the direction of the electric field.
a, 105b. Then, this displacement z is calculated as follows, where m is the mass of the incident charged particle, q is the electric charge, B is the strength of the magnetic field, and E is the strength of the electric field, z=π ² /2×E/B ² ×m/ q...(2) becomes. Since the ratio m/q of charge q to mass m of a charged particle is constant depending on the type of charged particle, which position-sensitive particle detector 105a, 105
The type of charged particle can be determined depending on whether it is incident on b. In addition, the position-sensitive particle detector 105
a, 105b, the energy K of the incident charged particle
Since the product K·y of the energy K and the incident position y is obtained, both the energy K and the incident position y of the charged particle are obtained. Also, the radius r of the semicircle drawn by the charged particle is is required. Therefore, as described above, if the mass m and energy K of a charged particle are determined, the radius r of its trajectory can be determined. Furthermore, since the incident position y of this charged particle is also determined as described above, which collimator 103a, 103b,
103c... can be determined. Therefore, as shown in FIG. 3, a charged particle that passes through the collimator 103a and draws a trajectory T ₁ with a radius r ₁ and a charged particle that passes through the collimator 103a and draws a trajectory T 1 with a radius
Even if charged particles that draw a trajectory T ₂ of r ₂ are incident on the same position of the position-sensitive particle detectors 105a, 105b, which collimator 103a,
103b, 103c, etc. can be determined. Therefore, these collimators 103
a, 103b, 103c, . . . can be arranged at as small intervals as necessary, regardless of the maximum radius of the trajectory drawn by the charged particles. Therefore, the spatial distribution of charged particles can be precisely measured, a large number of collimators 13a, 13b, 13c, . . . can be provided in one particle detection device, and the structure can be made simple and compact. Note that the position-sensitive particle detector 1
When charged particles incident on 05a and 105b pass through the electric field, their energy increases by △K=π ² /2 (E/B) ² m...(4), but this energy increase △K is Since this is extremely small compared to , it can be ignored, or the signal processing circuit 112 may correct it depending on the case.

Note that the present invention is not limited to the above embodiment.

For example, neutral particles can also be detected by providing a gas cell in or before and after a slit through which the particles pass, and converting the charge of the neutral particles to ionize them.

Furthermore, position-sensitive particle detectors are not necessarily limited to those using semiconductors, but may also use ionization type or other types.The point is to determine the energy and position of incident charged particles. It's fine as long as it's possible.

As described above, the present invention provides a plurality of slits that allow particles to be incident in a direction perpendicular to magnetic and electric fields that are parallel to each other and overlap each other, and that receives particles that are deflected in the magnetic and electric fields and detects the incident particles. A position-sensitive particle detector capable of detecting position and energy is provided. Therefore, since the type and energy of the incident particle and which slit it entered from are detected, the spacing between the multiple slits can be made as small as necessary, regardless of the maximum radius of the trajectory drawn by the particle in the magnetic field. It is possible to measure the spatial distribution of particles with high accuracy, and since a large number of slits can be provided in one device, the structure is simple and compact, and its effects are great. be.

[Brief explanation of the drawing]

1 and 2 show a conventional example, with FIG. 1 being a schematic plan view and FIG. 2 being a schematic side view. 3 to 5 show an embodiment of the present invention, in which FIG. 3 is a schematic plan view, FIG. 4 is a schematic side view, and FIG. 5 is a schematic configuration of a position-sensitive detector. It is a diagram. 101a, 101b...magnetic pole, 102a, 102
b...Electrode, 103a, 103b, 103c...Collimator, 104...Slit, 105a, 105b
...position-sensitive particle detector, 107...n-side electrode, 1
08...p side electrode.

Claims (1)

[Claims] 1 A pair of magnetic poles forming a uniform magnetic field, a pair of electrodes forming a uniform electric field parallel to and overlapping with this magnetic field, and arranged along a direction orthogonal to the magnetic field and the electric field, and the magnetic field and a plurality of slits that cause particles to enter the electric field in a direction perpendicular to these, and the energy of the particles that are provided along the direction in which the slits are arranged and are deflected by 180 degrees in the magnetic field, and the energy of the particles that are incident in the direction in which the slits are arranged. A particle detection device comprising: a position-sensitive particle detector for detecting the incident position of the particles in the direction along the particle detector.