WO2004107463A1 - ビーム電流計 - Google Patents
ビーム電流計 Download PDFInfo
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- WO2004107463A1 WO2004107463A1 PCT/JP2004/007346 JP2004007346W WO2004107463A1 WO 2004107463 A1 WO2004107463 A1 WO 2004107463A1 JP 2004007346 W JP2004007346 W JP 2004007346W WO 2004107463 A1 WO2004107463 A1 WO 2004107463A1
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- WIPO (PCT)
- Prior art keywords
- magnetic shield
- current sensor
- magnetic
- beam current
- squid
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/02—Details
- H01J37/24—Circuit arrangements not adapted to a particular application of the tube and not otherwise provided for
- H01J37/243—Beam current control or regulation circuits
Definitions
- the present invention relates to a beam ammeter, and more particularly, to a beam ammeter capable of measuring a weak beam current nondestructively and with high accuracy.
- the conventional magnetic modulation type DCCT has a problem that the lower limit of current measurement is on the order of several ⁇ A, and it is not possible to measure a weak beam current of about several nA.
- SQUID super is conductive
- GSI liquid helium temperature
- a beam ammeter capable of measuring a weak beam current of about several nA has a sensitivity 1000 times higher than a conventional beam ammeter that measures a beam current of the order of several ⁇ A. Will have.
- geomagnetism 10- 5 T cerebral magnetic field is 10- 13 T, since at the point of central force even 20cm of the magnetic field beam ⁇ produces is 1 0_ 15 T, weak in several nA
- a beam ammeter capable of measuring a large beam current must measure a very weak magnetic field.
- FIGS. 1 and 2 show a schematic structural configuration of a conventional beam ammeter using the above-described SQUID and a magnetic shield made of a superconductor operating at liquid helium temperature. I have. That is, FIGS. 1 and 2 are mechanical structural diagrams for contributing to the understanding of the present invention. Only the simple configuration is shown, and illustrations of various electrical connection states, electrical conduction states, and detection means for temperature and the like are omitted. 1 is a sectional view taken along line AA in FIG. 2, and FIG. 2 is a sectional view taken along line BB in FIG.
- reference numeral 1 denotes a beam current sensor made of a superconductor
- reference numeral 2 denotes a magnetic shield made of a superconductor
- reference numeral 3 denotes a SQUID
- reference numeral 4 denotes a refrigerant tank
- Reference numeral 5 indicates a vacuum container
- reference numeral 6 indicates an upper flange
- reference numeral 7 indicates a beam datum
- reference numeral 8 indicates a gantry
- reference numeral 9 indicates liquid helium as a refrigerant
- reference numeral 10 indicates the inside of the vacuum container 5.
- a vacuum region is shown
- reference numeral 11 indicates an atmospheric region outside the vacuum vessel 5.
- the upper surface 5a of the vacuum vessel 5 is closed by an upper flange 6, and through-holes 5c forming beam ducts 7 are formed at opposing positions on the peripheral wall, and the bottom surface 5b The side is supported on a gantry 8.
- the beam is made to enter from one through-hole 5c constituting one beam duct 7 and exit from the other through-hole 5c constituting the other beam duct 7.
- a cylindrical beam current sensor 1 is installed in the vacuum vessel 5 so that the beam incident into the vacuum vessel 5 passes through the inner diameter side, and a SQUID 3 is provided on the upper surface side of the beam current sensor 1. is set up.
- the SQUID 3 is positioned between the beam current sensor 1 and the cylindrical magnetic shield 2 made of a superconductor is installed so as to surround the outer diameter side of the beam current sensor 1.
- the above-described beam current sensor 1, SQUID 3, and magnetic shield 2 are arranged in a donut-shaped refrigerant tank 4, and the beam passes through a hollow portion on the inner diameter side of the donut-shaped refrigerant tank 4.
- the refrigerant tank 4 is filled with liquid helium as a refrigerant, and the beam current sensor 1, the SQUID 3, and the magnetic shield 2 disposed in the refrigerant tank 4 are cooled to the liquid helium temperature.
- a vacuum device not shown
- FIG. 3 is a schematic perspective view of the configuration of the beam current sensor 1 to which the SQUID 3 is attached.
- This beam current sensor 1 is formed by forming a linear insulator in a circumferential shape (headband shape) on the outer diameter side surface of a peripheral wall surface made of a superconductor, leaving only a partial region (bridge portion). Let's do it.
- the insulator is circumferentially arranged at the center of the beam current sensor 1 in the axial direction.
- SQUID3 is arranged in the above-mentioned bridge section.
- the SQUID3 Since the SQUID3 is arranged in the bridge, the magnetic field formed in the bridge due to the passage of current can be measured with high sensitivity, and the magnetic field measured with high sensitivity is converted into a current value, so that the beam current can be measured. Can be measured non-destructively and with high accuracy.
- the shielding current can be efficiently concentrated.
- a gradiometer In order to measure such a magnetic field formed in the azimuthal direction on the bridge portion with a good SN ratio, it is preferable to use a gradiometer as the SQUID3.
- the gradiometer has input coils for detecting the magnetic field on the left and right, and when external noise magnetic flux tries to enter the left and right input coils, if the magnitude and direction of the external noise magnetic field Is exactly the same, the external noise flux is completely canceled out, while the magnetic field formed in the bridge due to the passage of the beam has the same magnitude as described above. It's a reversed phase magnetic field with the opposite direction This is because a commonly used input coil can detect with twice the sensitivity compared to one type of SQUID.
- the external noise magnetic field can be significantly reduced, and by applying such superconducting technology, the sensitivity limit of the conventional magnetic modulation type DCCT can be greatly improved. Is now available.
- the magnetic shield 2 made of a superconductor is provided.
- the magnetic shield 2 for example, a bismuth-based superconducting material is fired at a thickness of 300 microns on a cylindrical ceramic made of magnesium oxide having a high purity of 99.9% or more. be able to. Note that creating such a magnetic shield requires processes such as baking and compression for about 4 weeks.
- an XY stage driven by a stepping motor equipped with a Helmholtz coil and an SQU ID system for magnetic field measurement were manufactured and measured. That is, as shown in Fig. 5, an external magnetic field is generated in the magnetic shield 2 by the Helmholtz coil, and the magnetic field is attenuated by driving the magnetic field probe equipped with the SQUID3 between the magnetic shield 2 and the beam current sensor 1. The rate was measured.
- Fig. 6 shows the results of measuring the attenuation rate of the magnetic field by applying a magnetic field of 3.5 ⁇ m in parallel with the magnetic shield 2 at a 1 Hz cycle.
- the position of the magnetic shield 2 Omm force Magnetic Shows the center of the cylindrical shape of the air shield 2.
- the attenuation rate S (z) is the magnetic field generated by the Helmholtz coil as B, and the magnetic field at the position z of the magnetic probe in the magnetic shield 2 is
- liquid helium is used as a refrigerant, which complicates the cooling mechanism.
- liquid helium itself which is a coolant (refrigerant) itself, is not low, there is a problem that the cost increases.
- liquid helium when used as a refrigerant, it takes several hours for SQUID to operate stably when replenishing liquid helium. there were.
- Non-Patent Document 2 "SQUID” based beam current meter, IEEE Trans, on Magnetics, Vol. MAG—21, No. 2, 1985, p. 997
- Non-Patent Document 3 i Cryogenic current comparator for the absolute mea surement of nA beams ", AIP Conf. Proc. 451 (Beam Instrumentation Workshop), 1998, p. 163
- Non-Patent Document 4 Design and performance of an HTS current comparat or for charged particle—beam measurements", L. Hao et al., IEE E Trans, on Appl. Supercond. (ASC2000), Vol. 11, No. 1, 20 01-3, p. 635
- Non-Patent Document 5 "High sensitivity measurement of beam current in storage ring", Tetsumi Tanabe, Megumi Shinada, Journal of the Physical Society of Japan Vol. 54, No. 1, 1999, p. 34
- the present invention has been made in view of the background of the invention as described above, the problems of the conventional technology, and the demand for the conventional technology, and an object thereof is to provide a superconductor cooling mechanism.
- the aim is to provide a beam ammeter that simplifies the process and enables significant cost reduction.
- Another object of the present invention is to provide a beam ammeter capable of sufficiently shielding an external magnetic field so as to perform highly sensitive beam current measurement without being affected by the external magnetic field. Things.
- a beam ammeter includes a beam current sensor, a SQUID, and a magnetic shield placed in a vacuum of an insulated vacuum vessel, and the beam current sensor, the SQUID, and a magnetic shield.
- the beam current sensor, the SQUID and the SQUID are cooled by using a refrigerator as the cooling means, and by conducting heat from the heat conduction means such as the cold head and cold finger of the refrigerator placed inside the insulated vacuum vessel.
- the magnetic shield is cooled.
- the beam ammeter according to the present invention there is no need to use a coolant such as liquid helium or liquid nitrogen, so that the cooling mechanism is simplified and the cost can be significantly reduced.
- liquid nitrogen when used as the refrigerant, there is a possibility that liquid oxygen is contained in the liquid nitrogen, and since liquid oxygen has magnetism and can be a noise source, liquid nitrogen is not used. In the beam ammeter, there is no need to take measures against noise generation by using liquid nitrogen.
- the magnetic shield has a multilayer structure so that the external magnetic field is sufficiently shielded and the beam current is measured with high sensitivity without being affected by the external magnetic field. That is, the present invention provides a cylindrical superconductor beam current sensor in which a beam incident into the vacuum vessel passes through the inner diameter side and a bridge portion is formed on the outer diameter side in the vacuum vessel. SQUID is arranged on the bridge part of the beam current sensor, and the SQUID is positioned between the beam current sensor and the beam current sensor. A magnetic shield made of a superconductor is provided, and the beam passes through the inner diameter side of the beam current sensor to measure the beam current of the beam. In the beam ammeter, the beam current sensor, the SQUID, and the magnetic shield are used. A refrigerator is used as a cooling means for one cell.
- the refrigerator has heat conduction means arranged in the vacuum vessel, and the beam current sensor, the SQUID, and the magnetic shield are cooled by heat conduction through the heat conduction means. That's what I did.
- the refrigerator is a pulse tube refrigerator.
- a heater is provided in the vacuum vessel in the vicinity of the SQUID so as to stabilize the temperature of the SQUID.
- a magnetic magnetic shield is provided so as to surround the magnetic shield in the vacuum vessel.
- a magnetic magnetic shield is provided so as to surround the vacuum container.
- the present invention Since the present invention is configured as described above, it has an excellent effect that the cooling mechanism of the superconductor can be simplified and the cost can be greatly reduced. .
- the present invention is configured as described above, it is possible to simplify the measurement work and to shorten the measurement time. It works.
- the present invention since the present invention is configured as described above, it has an excellent effect that the magnetic shield performance can be improved and high-sensitivity beam current measurement can be performed.
- FIG. 1 is a schematic sectional view of a conventional beam ammeter using a SQUID and a magnetic shield made of a superconductor operating at liquid helium temperature, and is a sectional view taken along line A—A in FIG. It is sectional drawing by a line.
- FIG. 2 is a schematic cross-sectional view of a conventional beam ammeter using a SQUID and a magnetic shield made of a superconductor operating at liquid helium temperature, and is a cross-sectional view taken along the line B_B in FIG. is there.
- FIG. 3 is a schematic perspective view of a configuration of a beam current sensor to which a SQUID is attached.
- FIG. 4 is an explanatory diagram of a gradiometer.
- FIG. 5 is an explanatory diagram of a SQUID system for measuring a magnetic field for measuring the effect of a magnetic shield.
- FIG. 6 is a graph showing the results of measuring the attenuation rate of the magnetic field using the SQUID system shown in FIG.
- FIG. 7 is a schematic cross-sectional explanatory diagram of a beam ammeter according to an example of an embodiment of the present invention, and is a cross-sectional view taken along line CC of FIG. 8 and line EE of FIG. 9;
- FIG. 8 is a schematic cross-sectional explanatory diagram of a beam ammeter according to an example of an embodiment of the present invention, and is a cross-sectional view taken along line DD of FIG. Garden 9]
- FIG. 9 is an explanatory diagram of a configuration of a beam ammeter according to an example of an embodiment of the present invention, and is an overall schematic external configuration diagram including an arrangement of a refrigerator.
- FIG. 10 is a schematic diagram of electric current of an electric heater.
- FIG. 11 is a block diagram showing a feedback circuit configuration of a SQUID element.
- FIG. 12 is a schematic cross-sectional explanatory diagram showing another embodiment of a beam ammeter according to the present invention.
- FIG. 8 is a cross-sectional view corresponding to FIG. 1 and FIG.
- FIG. 13 is a schematic structural explanatory view showing another embodiment of the beam ammeter according to the present invention.
- FIG. 14 is an enlarged conceptual sectional view of an end portion shown by a circular broken line in FIG. Garden 15]
- FIG. 15 is an enlarged conceptual sectional view showing another embodiment of the beam ammeter according to the present invention, and is a sectional view corresponding to FIG.
- Pulse tube refrigerator a Cornoledo, head b Norelev motor c Gas compressor
- FIGS. 7 to 9 and FIGS. 12 to 15 showing the beam ammeter according to the present invention described below show only the mechanical structure of the beam ammeter according to the present invention.
- known techniques can be applied. Therefore, illustration is omitted, and the description is appropriately made using known techniques. Omitted.
- FIG. 7, FIG. 8, and FIG. 9 show a schematic structural configuration of a beam ammeter according to an example of the embodiment of the present invention.
- Fig. 7 is a cross-sectional view taken along line C-C in Fig. 8 and a line E-E in Fig. 9
- Fig. 8 is a cross-sectional view taken along line D-D in Fig. 7, and
- Fig. 9 includes the arrangement of the refrigerator.
- FIG. 1 is an overall schematic configuration diagram. 7 is a drawing corresponding to FIG. 1 described above, and FIG. 8 is a drawing corresponding to FIG. 2 described above.
- the vacuum container 5 ′ is configured as an insulated vacuum container, and the upper surface 5 ′ a side of the vacuum container 5 ′ is an upper flange having an opening 6 ′ a formed in the center. Blocked by 6 '. As will be described later, the cold finger 12f connected to the cold head 12a of the pulse tube refrigerator 12 is inserted through the opening 6'a into the vacuum vessel 5 '.
- reference numeral 12 denotes a pulse tube refrigerator as a refrigerator for cooling the beam current sensor 1, SQUID 3, and magnetic shield 2 disposed in the vacuum vessel 5 '
- reference numeral 12a denotes a pulse
- the reference numeral 12f denotes a cold finger as a heat conduction means of the pulse tube refrigerator 12, and the cold finger 12f connected to the cold head 12a denotes a vacuum.
- the inside of the vacuum vessel 5 ' is communicated from the opening 6'a of the vessel 5'.
- reference numeral 12b denotes a valve motor of the pulse tube refrigerator 12 installed on the gantry 8
- reference numeral 12c denotes a gas compressor of the pulse tube refrigerator 12
- reference numeral 12d denotes a gas piping of the pulse tube refrigerator 12.
- Reference numeral 12e denotes a gas pipe of the pulse tube refrigerator 12
- reference numeral 12f denotes a cold finger connected to the cold head 12a as described above
- reference numeral 13 denotes a cold finger 12f connected to the cold finger 12f.
- reference numeral 14 denotes a pair of donut shaped to support the beam current sensor 1 and the magnetic shield 2.
- Reference numeral 15 denotes a mechanically flexible braided conductor arranged to connect the cooling plate 13 and the support plate 14 to ensure heat conduction
- reference numeral 16 denotes a pair.
- Thermal conductive sheets are provided between the support plate 14 and both end surfaces of the beam current sensor 1 and the magnetic shield 2 to reduce thermal resistance
- reference numeral 17 denotes a fastening for connecting the pair of support plates 14.
- Reference numeral 18 denotes a nut for fixing the tightening bolt 17 to the support plate 14
- reference numeral 19 denotes a spring disposed between the support plate 14 and the nut 18, and reference numeral 20 denotes one side.
- Reference numeral 21 denotes an anti-vibration rubber provided between the gantry 8 and the bottom surface 5 ′ b of the vacuum vessel 5 ′
- reference numeral 22 denotes an electric power attached to the cooling plate 13 as a position near the SQUID 3. Show the heater.
- Reference numeral 5′c indicates a through hole that constitutes the beam duct 7 at a position facing the peripheral wall surface.
- cryogenic cable connecting the SQUID3 and the controller (not shown) is connected to the atmosphere through a vacuum-tight flange (not shown).
- the control signal is digitized between the controller and the feedback circuit (see Fig. 11) to minimize the electrical noise that is mixed into the signal. Communication is performed through the network.
- the electric heater 22 is disposed on the cooling plate 13 near the SQUID 3. Since SQUID3 requires a stability within several mK, the heating amount of the electric heater 22 is controlled so that the temperature of SQUID3 is kept constant. That is, a temperature sensor (not shown) is attached to the cooling plate 13 together with the electric heater 22, and a temperature controller (not shown) for controlling the amount of heating of the electric heater 22 transmits temperature information from the temperature sensor. Based on the above, feedback is applied to the current value of the electric heater 22 to stabilize the temperature of the SQUID3. In order to realize the high stability of the temperature of SQUID3, for example, PID (Proportional plus Integral plus Derivative) control can be used as the temperature controller.
- PID Proportional plus Integral plus Derivative
- the bottom surface 5 ′ of the vacuum vessel 5 ′ is supported on the gantry 8 via a vibration-proof rubber 21.
- the beam enters from one through-hole 5'c constituting one beam duct 7 and exits from the other through-hole 5'c constituting the other beam duct 7. Has been done.
- a cylindrical beam current sensor 1 is installed so that the beam incident into the vacuum vessel 5 ′ passes through the inner diameter side.
- the SQUID 3 is positioned between the beam current sensor 1 and the cylindrical magnetic shield 2 made of a superconductor is installed so as to surround the outer diameter side of the beam current sensor 1.
- the above-described beam current sensor 1 and the magnetic shield 2 in which the SQUID 3 are arranged are supported at both ends thereof by a pair of donut-shaped support plates 14, and the pair of support plates 14 are fastened by tightening bolts 17 and nuts 18.
- the magnetic shield 2 in which the beam current sensor 1 and the SQUID 3 are arranged and the support plate 14 are integrated.
- the integrated beam current sensor 1, magnetic shield 2 having SQUID 3 arranged thereon, and support plate 14 are arranged such that the beam incident into vacuum vessel 5 ′ is formed on the inner diameter side of beam current sensor 1 and the inner diameter side of support plate 14. It is arranged in a vacuum vessel 5 'via a heat insulating support rod 20 in such a positional relationship as to pass through the space.
- one end of the heat insulating support rod 20 is The other end of the heat insulating support rod 20 is fixed to the support plate 14 while being fixed to the inner wall surface of the vacuum vessel 5 ′.
- Two heat-insulating support rods 20 are provided for each support plate 14, and only an angle P (the angle P is preferably 10 degrees or more) outward with respect to the center line OO in FIG. In addition to being tilted, it is tilted outward by an angle Q (the angle Q is preferably 10 degrees or more) with respect to the center line 0-0 in FIG.
- the support plate 14 is connected to the cooling plate 13 via a braided conductor 15, and the support plate 14 and the beam current sensor are connected by heat conduction from the cooling plate 13 connected to the cold head 12a via the cold finger 12f. 1, magnetic shield 2 and SQUID3 are configured to be cooled.
- the support plate 14 serves to mechanically support the beam current sensor 1 and the magnetic shield 2 and to perform heat conduction cooling, a material having high mechanical strength and good heat conduction, for example, It is preferable to be made of copper or the like.
- the contact parts of the cold head 12a, cold finger 12f, cooling plate 13, braided conductor 15, support plate 14, heat conduction sheet 16, beam current sensor 1, magnetic shield 2 and SQUID3 include oil compound and apiezon grease. It is preferable to apply a material having good heat conductivity even at a low temperature.
- the measurement principle of the beam ammeter using such a beam current sensor 1 and SQUID3 is the same as the measurement principle described in the section of "Background of the Invention and Conventional Technology" above, and the description is incorporated herein. Thus, the description thereof will be omitted.
- current sensor 1, magnetic shield 2, and SQUID 3 are arranged in a vacuum, and serve as a heat conducting means of pulse tube refrigerator 12.
- Current sensor 1, magnetic shield 2 and SQUID3 are cooled by heat conduction from cold head 12a and cold finger 12f. That is, a liquid helicopter is used to cool the current sensor 1, magnetic shield 2, and SQUID3. Since there is no need to use liquid nitrogen, there is no need to use a refrigerant tank 4 for storing the refrigerant as shown in Fig. 1, so the cooling mechanism is simplified and manufacturing costs can be significantly reduced. .
- liquid helium itself is expensive, but there is no need to use such an expensive refrigerant.
- the current sensor 1, the magnetic shield 2, and the SQUID 3 receive a vibration noise as a refrigerator that cools the current sensor 1, the magnetic shield 2, and the SQUID 3.
- a pulse tube refrigerator 12 having no moving parts in the refrigeration generator is used.
- a valve motor 12b is installed on the gantry 8, and an anti-vibration rubber 21 is provided between the gantry 8 and the vacuum vessel 5 '.
- This arrangement prevents the mechanical vibration of the valve motor 12b from being transmitted to the current sensor 1, the magnetic shield 2, and the SQUID 3, and the mechanically flexible braided conductor 15 makes the cooling plate 13 and the support plate 14 The transmission of the mechanical vibration from the cold head 12a, the cold finger 12f, and the cooling plate 13 to the current sensor 1, the magnetic shield 2, and the SQUID 3 is reduced.
- the pulse tube refrigerator 12 used in the present embodiment operates at a pumping cycle of 5.5 Hz, for example. It is preferable to calculate the frequency and select an anti-vibration rubber 21 having an appropriate spring multiplier so that the two frequencies do not match.
- the tightening strength is increased by disposing a disc spring 19 between the tightening bolt 18 and the support plate 14.
- the support plate 14 is supported by two heat-insulating support rods 20, and the angles P and Q, which are the inclination angles at the time of attachment, are set to 10 degrees or more. This increases the support rigidity in the horizontal direction and reduces the occurrence of mechanical vibration. Further, since the cold head 12a is supported by the upper flange 6 ', assembly and disassembly can be easily performed.
- the temperature of the SQUID 3 is controlled to be constant by controlling the heating amount of the electric heater 22 arranged on the cooling plate 13. I have to.
- the electric heater 22 will be described with reference to a schematic current diagram of the electric heater 22 shown in FIG.
- the electric heater 22 generates a magnetic field when an electric current is applied to the electric heater 22 configured as a so-called film heater, and this becomes disturbance noise of the SQUID 3.
- the electric heater 22 is formed by stacking two film heaters, and the current directions of the upper and lower film heaters are arranged in opposite directions so as to reduce the generation of a magnetic field from the electric heater 22. I have to.
- the feedback circuit shown in FIG. 11 is used.
- the SQUID element is magnetically coupled with the pickup coil, input coil, feedback coil, and modulation coil.
- the magnetic field B induced in the pickup coil is transmitted to the input coil, and the voltage across the SUIQD element tries to change.
- current is passed through the feedback coil of the feedback circuit so that the change is restored.
- PLL Phase Locked Loop
- FIG. 12 is a cross-sectional view corresponding to FIG. 1 and FIG.
- a plurality of magnetic magnetic shields made of a high magnetic permeability material are arranged in order to improve the magnetic shield performance.
- reference numeral 23 indicates the magnetic first magnetic shield
- reference numeral 23a indicates the disk portion of the magnetic first magnetic shield
- reference numeral 23b indicates the cylindrical portion of the magnetic first magnetic shield
- reference numeral 24 Denotes a magnetic second magnetic shield
- reference numeral 25 denotes a chimney shield
- reference numeral 26 denotes a magnetic third magnetic shield
- reference numeral 27 denotes a chimney shield.
- the magnetic first magnetic shield 23 including the disk portion 23a and the cylindrical portion 23b is provided close to the magnetic shield 2.
- the disk portion 23a of the magnetic first magnetic shield 23 is disposed between the support plate 14 and the ends of the current sensor 1 and the magnetic shield 2, while the cylindrical portion of the magnetic first magnetic shield 23 is The portion 23b is arranged so that the peripheral wall portion is located between the magnetic shield 2 and the cooling plate 13.
- the magnetic first magnetic shield 23 composed of the disk portion 23a and the cylindrical portion 23b in close proximity to the magnetic shield 2 in this manner, it is possible to improve the magnetic shield performance for the SQUID3.
- the gap g between the disk portion 23a and the cylindrical portion 23b the magnetic shielding performance can be further improved.
- the gap g is preferably, for example, 0.5 mm or more.
- the magnetic second magnetic shield 24 is a vacuum vessel including the current sensor 1, the magnetic shield 2, the SQUID 3 and the support plate 14, the cooling plate 13 and the braided conductor 15 integrated by connecting the pair of support plates 14. It is arranged so as to cover each component in 5 '. By arranging such a magnetic second magnetic shield 24, the magnetic shield performance can be further improved.
- the magnetic third magnetic shield 26 is placed in the atmosphere so as to cover the entire vacuum vessel 5 '.
- the magnetic shield performance can be further improved. Can be improved.
- the through hole 24a for penetrating the cold finger 12f in the magnetic second magnetic shield 24 has a deteriorated magnetic shield performance.
- the chimney shield 25 as a magnetic magnetic shield that rises from the through hole 24a along the cold finger 12f, it is possible to reduce the influence of the decrease in the magnetic shield performance due to the through hole 24a.
- the diameter d of the chimney shield 25, that is, the ratio of the diameter of the through hole 24 to the height h, h / d, is 1 or more.
- a chimney shield 27 as a magnetic magnetic shield extending along the beam duct 7 can also be provided in the through-hole 26a through which the beam duct 7 in the magnetic third magnetic shield 26 passes.
- magnetic first magnetic shield 23, magnetic second magnetic shield 24, chimney shield 25, magnetic third magnetic shield 26, and chimney shield 27 are attached to or adhered to a high-conductivity material to provide shielding performance against radio waves. Can be further improved.
- FIGS. 13 to 15 show other embodiments of the beam ammeter according to the present invention, and the magnetic shielding performance of the superconducting magnetic shield itself can be improved.
- the superconducting magnetic shield end plates 28 are arranged at both ends of the current sensor 1 and the magnetic shield 2, respectively. By disposing such a superconducting magnetic shield end plate 28, it is possible to improve the magnetic shield performance.
- FIG. 14 is an enlarged conceptual cross-sectional view of an end portion shown by a circular broken line in FIG.
- a superconductor is formed on the surface of a ceramic or metal substrate. It is formed by making a film of.
- the symbol la indicates the substrate (usually ceramic or metal is used) of the current sensor 1
- the symbol lb indicates the superconductor film
- the current sensor 1 It is constructed by joining a superconductor film lb to a substrate la.
- the superconductor film lb of the current sensor 11 is formed on the inner peripheral wall, the end surface, and the outer peripheral wall of the cylindrical substrate la for measuring the beam current.
- Reference numeral 2a denotes a magnetic shield substrate (usually ceramic or metal is used), reference numeral 2b denotes a superconductor film, and magnetic shield 2 denotes a superconductor film 2b to the substrate 2a. It is constituted by joining to.
- the superconductor film 2b of the magnetic shield 2 is formed only on the outer peripheral wall of the cylindrical substrate 2a.
- reference numeral 28a denotes a substrate (usually ceramic or metal is used) of the superconducting magnetic shield end plate 28
- reference numeral 28b denotes a superconductor film, and the superconducting magnetic shield end plate 28 is provided. Is formed by bonding a superconductor film 28b to a substrate 28a.
- the superconductor film 28b of the superconducting magnetic shield end plate 28 is formed only on one surface of the donut-shaped substrate 28a (the surface facing the end surfaces of the current sensor 1 and the magnetic shield 2).
- the thickness of the superconductor films lb, 2b and 28b is, for example, about 0.1 mm.
- gaps gl and g2 between the end of the current sensor 1 and the magnetic shield 2 created as described above and the superconducting magnetic shield end plate 28 due to manufacturing errors.
- the presence of such gaps gl and g2 makes it difficult to improve the magnetic shielding performance. For example, even if the gaps gl and g2 have a gap of 0.05 mm, the improvement in the magnetic shield performance is small.
- the superconducting magnetic shield end plate of the magnetic shield 2 needs to be improved as shown in FIG.
- the superconductor 2b may be formed on the end face opposite to.
- the ratio gl / hl which is the ratio of the gap gl to the thickness hi of the current sensor 1
- the ratio g2Zh2 which is the ratio of the gap g2 to the thickness h2 of the magnetic sensor 2
- the magnetic shield performance can be improved.
- the current sensor 1, the magnetic shield 2, and the SQ The type of superconductor that constitutes UID3 is not particularly limited, but the superconductor that constitutes current sensor 1, magnetic shield 2, and SQUID3 operates at low temperature (liquid helium temperature). Either a conductor or a high-temperature superconductor operating at a high temperature (liquid nitrogen temperature) can be used.
- the shapes of the current sensor 1 and the magnetic shield 2 are cylindrical, but it is a matter of course that the present invention is not limited to this. That is, the current sensor 1 and the magnetic shield 2 may have an elliptical cylindrical shape or a polygonal cylindrical shape in addition to a cylindrical shape as long as they have a cylindrical shape.
- the support plate 14 may be appropriately modified in a donut shape according to the cylindrical shape of the current sensor 1 and the magnetic shield 2.
- heat-insulating support rods 20 are provided for each support plate 14, but it is a matter of course that the present invention is not limited to this.
- One heat-insulating support rod 20 may be provided on each support plate 14, or three or more heat-insulating support rods 20 may be provided. Further, the number of heat insulating support rods 20 provided on one support plate 14 and the number of heat insulating support rods 20 provided on the other support plate 14 may be different.
- the magnetic first magnetic shield 23, the magnetic second magnetic shield 24, the chimney shield 25, the magnetic third magnetic shield 26, and the chimney shield 27 are all provided. Needless to say, it is not necessary to dispose all of these forces. Of the first magnetic shield 23, the second magnetic shield 24, the chimney shield 25, the third magnetic shield 26, and the chimney shield 27, a desired one may be appropriately and selectively disposed. ,. Also, as for the magnetic first magnetic shield 23, it is not necessary to dispose both the disk portion 23a and the cylindrical portion 23b, and only one of them may be disposed.
- the pulse tube refrigerator is used as the refrigerator that cools the current sensor 1, the magnetic shield 2, and the SQ UID3 to reduce mechanical vibration, but is not limited thereto. If the effect of mechanical vibrations is not a problem, a refrigerator having a mechanical drive device in the cold head may be used.
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- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Containers, Films, And Cooling For Superconductive Devices (AREA)
- Measuring Magnetic Variables (AREA)
- Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)
- Superconductor Devices And Manufacturing Methods Thereof (AREA)
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10/558,419 US7435970B2 (en) | 2003-05-30 | 2004-05-28 | Beam current meter |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2003155407A JP4550375B2 (ja) | 2003-05-30 | 2003-05-30 | ビーム電流計 |
JP2003-155407 | 2003-05-30 |
Publications (1)
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WO2004107463A1 true WO2004107463A1 (ja) | 2004-12-09 |
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PCT/JP2004/007346 WO2004107463A1 (ja) | 2003-05-30 | 2004-05-28 | ビーム電流計 |
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US (1) | US7435970B2 (ja) |
JP (1) | JP4550375B2 (ja) |
WO (1) | WO2004107463A1 (ja) |
Families Citing this family (10)
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JP4252908B2 (ja) | 2004-02-10 | 2009-04-08 | パナソニック株式会社 | ビーム測定装置およびこれを用いたビーム測定方法 |
JP5208481B2 (ja) * | 2007-11-02 | 2013-06-12 | 公益財団法人鉄道総合技術研究所 | 極低温容器の支持装置 |
US9535100B2 (en) | 2012-05-14 | 2017-01-03 | Bwxt Nuclear Operations Group, Inc. | Beam imaging sensor and method for using same |
US9383460B2 (en) | 2012-05-14 | 2016-07-05 | Bwxt Nuclear Operations Group, Inc. | Beam imaging sensor |
JP6044033B2 (ja) * | 2013-01-22 | 2016-12-14 | 国立研究開発法人理化学研究所 | 荷電粒子ビームの電流検知装置 |
JP6411131B2 (ja) * | 2014-08-27 | 2018-10-24 | 超電導センシング技術研究組合 | 振動センサ及び振動センシングシステム |
CN104409401B (zh) * | 2014-12-26 | 2017-02-22 | 合肥彩虹蓝光科技有限公司 | 一种等离子清洗设备 |
CN105068110B (zh) * | 2015-08-27 | 2018-04-13 | 广东恒聚医疗科技有限公司 | 一种新型束流探测器 |
JP7332413B2 (ja) * | 2019-09-27 | 2023-08-23 | 明星工業株式会社 | 低温熱伝導率測定装置 |
CN114034906B (zh) * | 2021-11-09 | 2023-03-21 | 南京大学 | 一种用于弱束流信号测量的交流电流互感器探头模块 |
Citations (5)
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JPS6418280A (en) * | 1987-07-13 | 1989-01-23 | Sharp Kk | Superconducting device |
JPH07135099A (ja) * | 1993-11-09 | 1995-05-23 | Japan Atom Energy Res Inst | イオンビーム電流測定装置および方法 |
JP2000275289A (ja) * | 1999-03-24 | 2000-10-06 | Sumitomo Heavy Ind Ltd | マイクロ波検出装置、その製造方法及び超伝導素子を用いた電磁波検出装置 |
JP2001066354A (ja) * | 1999-08-30 | 2001-03-16 | Hitachi Ltd | 超電導量子干渉デバイス格納用極低温容器 |
JP2003021670A (ja) * | 2001-07-08 | 2003-01-24 | Yuichiro Sasaki | 非接触型イオンビーム電流強度測定装置 |
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US4687987A (en) * | 1984-09-28 | 1987-08-18 | The United States Of America As Represented By The United States Department Of Energy | Beam current sensor |
EP0288022B1 (en) | 1987-04-22 | 1995-11-15 | Sharp Kabushiki Kaisha | Superconductive apparatus |
JPS6418280U (ja) | 1987-07-23 | 1989-01-30 | ||
JP2001066351A (ja) | 1999-08-30 | 2001-03-16 | Sony Corp | 回路基板検査装置及びコネクタ |
US7888937B2 (en) * | 2003-09-24 | 2011-02-15 | Riken | Beam current sensor |
-
2003
- 2003-05-30 JP JP2003155407A patent/JP4550375B2/ja not_active Expired - Fee Related
-
2004
- 2004-05-28 US US10/558,419 patent/US7435970B2/en not_active Expired - Fee Related
- 2004-05-28 WO PCT/JP2004/007346 patent/WO2004107463A1/ja active Application Filing
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
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JPS6418280A (en) * | 1987-07-13 | 1989-01-23 | Sharp Kk | Superconducting device |
JPH07135099A (ja) * | 1993-11-09 | 1995-05-23 | Japan Atom Energy Res Inst | イオンビーム電流測定装置および方法 |
JP2000275289A (ja) * | 1999-03-24 | 2000-10-06 | Sumitomo Heavy Ind Ltd | マイクロ波検出装置、その製造方法及び超伝導素子を用いた電磁波検出装置 |
JP2001066354A (ja) * | 1999-08-30 | 2001-03-16 | Hitachi Ltd | 超電導量子干渉デバイス格納用極低温容器 |
JP2003021670A (ja) * | 2001-07-08 | 2003-01-24 | Yuichiro Sasaki | 非接触型イオンビーム電流強度測定装置 |
Also Published As
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US20070069722A1 (en) | 2007-03-29 |
JP2004356573A (ja) | 2004-12-16 |
US7435970B2 (en) | 2008-10-14 |
JP4550375B2 (ja) | 2010-09-22 |
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