A Kinetic Capacitor for DC Current Modulation

Abstract

The present invention discloses a dynamic capacitor for direct current modulation. The vibrating electrode in the dynamic capacitor for direct current modulation of the present invention can vibrate freely. When a periodic current is loaded on the enameled coil, an alternating magnetic field is generated at the center of the enameled coil, and the vibrating electrode of the dynamic capacitor vibrates periodically under the alternating magnetic field, resulting in a periodic change in the capacitance of the dynamic capacitor. When a certain amount of charge is loaded on the dynamic capacitor, the output end of the dynamic capacitor will modulate an alternating voltage signal with a stable frequency and amplitude. The charge can be generated by the current output by the current type detector. The amplitude of the alternating voltage signal output by the dynamic capacitor is proportional to the current output by the detector. The dynamic capacitor for direct current modulation of the present invention is installed in the output modulation module of the current type detector, and is suitable for a wide range of 10 ‑6 A~10 ‑13 The DC current modulation of A can realize the measurement of the DC current output by the tritium ionization chamber in a special radiation environment.

Description

Technical Field

[0001] The invention belongs to the field of radiation detection technology and radiation protection, and in particular relates to a dynamic capacitor used for output current modulation of a current type detector. Background Art

[0002] During the laser fusion target shooting process, the target pellet is heated by the laser and vaporized instantly, and deuterium and tritium gas is quickly released into the target chamber. Tritium is a β-radioactive nuclide with a half-life of 13.33 years. The maximum energy of the β-ray emitted by decay is 18.6keV, and its average energy is about 5.9keV. Tritium can penetrate into the human body through breathing, eating, and skin, causing human tissue to be exposed to radioactive internal irradiation. Therefore, the tritium concentration must be monitored in real time during the maintenance of the target chamber to ensure the radiation safety of personnel.

[0003] The beta particles of tritium have low energy and weak penetration ability. The tritium-containing gas must be introduced into the sensitive area of ​​the detector to achieve tritium measurement. The ionization chamber is a conventional detector for measuring tritium concentration. Under passive sampling, the tritium-containing gas enters the ionization chamber by free diffusion. Under active sampling, the tritium-containing gas to be measured is pumped into the ionization chamber through a vacuum pump and a vacuum pipe. After the ionization chamber is loaded with an appropriate bias voltage, the tritium concentration is measured by measuring the current at the collecting end of the detector. In the target chamber of the fusion device, the wide range of tritium concentration leads to a large range of ionization output current, which requires the measurement device to have both a wide range and a highly sensitive current measurement capability.

[0004] At present, the measurement of the output current of the ionization chamber is mainly achieved through a pre-stage current sensitive amplifier made of a high-performance operational amplifier chip. However, in the strong radiation environment of deuterium-tritium fusion, the high-sensitivity chip is easily damaged by radiation, resulting in failure of the current measurement system. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a dynamic capacitor for output current modulation of a current type detector.

[0006] The dynamic capacitor for DC current modulation of the present invention is characterized in that: the dynamic capacitor comprises an insulator I, a fixed electrode, a vibrating electrode, a vibrator, an electromagnetic suction piece, a winding disk, an enameled coil, a shell, a grounding electrode, an insulator II, a coil positive electrode, a coil negative electrode and a countersunk screw;

[0007] The shell is cylindrical, the left end of the shell is a closed end, the insulator I is fixedly installed at the center of the left end of the shell, and the right end of the shell is an open end;

[0008] The fixed electrode comprises a horizontal guide rod on the left and a vertical circular plate on the right, the horizontal guide rod penetrates and is fastened to the center of the insulator I, and the vertical circular plate is located in the cavity of the shell;

[0009] The vibrating electrode has the same structure as the fixed electrode. The vibrating electrode comprises a vertical circular electrode plate on the left and a horizontal guide rod on the right. The vibrating electrode and the fixed electrode are placed symmetrically. There is a gap between the vertical circular electrode plate of the vibrating electrode and the vertical circular electrode plate of the fixed electrode. The electromagnetic suction piece is fixed to the right end of the horizontal guide rod of the vibrating electrode.

[0010] The vibrator comprises two vibrating plates, the horizontal guide rods of the vibrating electrodes sequentially pass through the two vibrating plates and are fixed on the centers of the two vibrating plates, the two vibrating plates are located between the vertical circular plates of the vibrating electrodes and the electromagnetic suction plates, and the upper and lower ends of each vibrating plate are fixed on the inner surface of the housing;

[0011] The left and right sides of the winding drum are disks, and the middle is a round rod. A gap is left between the left disk of the winding drum and the electromagnetic suction piece. An enameled coil is evenly wound on the round rod of the winding drum. The right disk of the winding drum is installed on the right end of the shell through countersunk screws evenly distributed along the outer circumference and closes the right end of the shell; two insulators II are also installed on the right disk of the winding drum, the center of one insulator II is fixed with a coil positive electrode, and the center of the other insulator II is fixed with a coil negative electrode, and the two ends of the enameled coil are respectively welded to the left ends of the coil positive electrode and the coil negative electrode; a grounding electrode is also installed on the right disk of the winding drum; the right ends of the coil positive electrode and the coil negative electrode and the grounding electrode are connected to an external power supply.

[0012] A layer of gold film with a thickness of 2 to 4 microns is electroplated on the surface of the vertical circular plates of the fixed electrode and the vibrating electrode, and the surface roughness of the vertical circular plates is less than or equal to Ra0.2.

[0013] The materials of insulators I and II are ceramic, the materials of fixed electrode and vibration electrode are 316L stainless steel, the materials of vibrator, electromagnetic suction plate and winding disk are Permalloy, the material of shell is electromagnetic pure iron, and the materials of ground electrode, coil positive electrode and coil negative electrode are brass.

[0014] The inner and outer surfaces of the vibrator, the electromagnetic suction piece, the winding disk and the shell are all electroplated with a layer of gold film.

[0015] The insulator I and the insulator II are fixed by sintering; the vibrator and the electromagnetic suction piece are fixed by welding.

[0016] The vibrating electrode in the dynamic capacitor for DC current modulation of the present invention can vibrate freely. When a sinusoidal alternating current is loaded to the enameled coil, an alternating magnetic field is generated at the center of the enameled coil, and the vibrating electrode of the dynamic capacitor performs sinusoidal vibration under the alternating magnetic field. The frequency of the vibration is twice the frequency of the loaded alternating current, and causes the capacitance value of the dynamic capacitor to change periodically. When a certain amount of charge is loaded at both ends of the dynamic capacitor, an alternating voltage signal with a stable frequency and amplitude can be modulated at the output end of the dynamic capacitor due to the vibration of the vibrating electrode. The charge can be generated by the current output by the current type detector flowing through a large load resistor. The amplitude of the alternating voltage signal is proportional to the current output by the detector, and the coefficients of the two are calibrated by a standard current source.

[0017] The dynamic capacitor for DC current modulation of the present invention is installed in the output modulation module of the current type detector, which is suitable for a wide range of 10 -6 A~10 -13 The DC current modulation of A can realize the measurement of the DC current output by the tritium ionization chamber in a special radiation environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of a dynamic capacitor for direct current modulation of the present invention;

[0019] In the figure, 1. Insulator I 2. Fixed electrode 3. Vibrating electrode 4. Vibrator 5. Electromagnetic suction piece 6. Winding disk 7. Enameled coil 8. Shell 9. Grounding electrode 10. Insulator II 11. Coil positive electrode 12. Coil negative electrode 13. Countersunk screw. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] like Figure 1 As shown, the dynamic capacitor for DC current modulation of the present invention comprises an insulator Ⅰ1, a fixed electrode 2, a vibrating electrode 3, a vibrator 4, an electromagnetic suction piece 5, a winding disk 6, an enameled coil 7, a housing 8, a grounding electrode 9, an insulator Ⅱ10, a coil positive electrode 11, a coil negative electrode 12 and a countersunk screw 13;

[0022] The shell 8 is cylindrical, the left end of the shell 8 is a closed end, the insulator Ⅰ1 is fixedly installed at the center of the left end of the shell 8, and the right end of the shell 8 is an open end;

[0023] The fixed electrode 2 comprises a horizontal guide rod on the left and a vertical circular plate on the right, the horizontal guide rod penetrates and is fastened to the center of the insulator Ⅰ1, and the vertical circular plate is located in the cavity of the housing 8;

[0024] The vibration electrode 3 has the same structure as the fixed electrode 2. The vibration electrode 3 includes a vertical circular electrode plate on the left and a horizontal guide rod on the right. The vibration electrode 3 and the fixed electrode 2 are placed symmetrically. There is a gap between the vertical circular electrode plate of the vibration electrode 3 and the vertical circular electrode plate of the fixed electrode 2. The electromagnetic suction piece 5 is fixed to the right end of the horizontal guide rod of the vibration electrode 3.

[0025] The vibrator 4 comprises two vibrating plates, the horizontal guide rods of the vibrating electrode 3 pass through the two vibrating plates in sequence and are fixed on the centers of the two vibrating plates, the two vibrating plates are located between the vertical circular plates of the vibrating electrode 3 and the electromagnetic suction plate 5, and the upper and lower ends of each vibrating plate are fixed on the inner surface of the housing 8;

[0026] The left and right sides of the winding drum 6 are disks, and the middle is a round rod. There is a gap between the left disk of the winding drum 6 and the electromagnetic suction piece 5. The enameled coil 7 is evenly wound on the round rod of the winding drum 6. The right disk of the winding drum 6 is installed on the right end of the shell 8 and closes the right end of the shell 8 through countersunk screws 13 evenly distributed along the outer circumference; two insulators II 10 are also installed on the right disk of the winding drum 6, and the center of one insulator II 10 is fixed with a coil positive electrode 11, and the center of the other insulator II 10 is fixed with a coil negative electrode 12. The two ends of the enameled coil 7 are respectively welded to the left ends of the coil positive electrode 11 and the coil negative electrode 12; a grounding electrode 9 is also installed on the right disk of the winding drum 6; the right ends of the coil positive electrode 11 and the coil negative electrode 12 and the grounding electrode 9 are connected to an external power supply.

[0027] A layer of gold film with a thickness of 2 to 4 microns is electroplated on the surface of the vertical circular plates of the fixed electrode 2 and the vibrating electrode 3, and the surface roughness of the vertical circular plates is less than or equal to Ra0.2.

[0028] The insulator I1 and insulator II10 are made of ceramic, the fixed electrode 2 and the vibrating electrode 3 are made of 316L stainless steel, the vibrator 4, the electromagnetic suction piece 5 and the winding disk 6 are made of Permalloy, the shell 8 is made of electromagnetic pure iron, and the grounding electrode 9, the coil positive electrode 11 and the coil negative electrode 12 are made of brass.

[0029] The inner and outer surfaces of the vibrator 4, the electromagnetic suction plate 5, the winding drum 6 and the shell 8 are all electroplated with a layer of gold film.

[0030] The insulator I1 and the insulator II10 are fixed by sintering; the vibrator 4 and the electromagnetic suction piece 5 are fixed by welding.

[0031] Example 1

[0032] The modulation of the DC current by the dynamic capacitor for DC current modulation of the present invention comprises the following steps:

[0033] 1. Generation of alternating magnetic field

[0034] When a sinusoidal AC current is input into the enameled coil, the magnetic induction intensity generated on the left end face of the winding disk is:

[0035] (1)

[0036] Where:

[0037] -Magnetic induction intensity, unit T;

[0038] - Vacuum magnetic permeability, value is 4π×10 -7 T·m / A;

[0039] -Relative magnetic permeability, dimensionless;

[0040] -The number of turns of the enameled coil, dimensionless;

[0041] - Input alternating current amplitude, in A;

[0042] -angular frequency of the current, in 2π / s;

[0043] -Time, in seconds.

[0044] 2. The suction force of electromagnetic force on electromagnetic suction piece

[0045] The electromagnetic suction piece is very close to the left end of the winding disk, and the material is consistent. The suction force of the electromagnetic field on the electromagnetic suction piece is:

[0046] (2)

[0047] Where:

[0048] - is the electromagnetic suction force of the electromagnetic suction plate, in N;

[0049] - is the area of ​​the electromagnetic suction piece and the magnetic core, in m 2 ;

[0050] -Half suction force, , unit is N;

[0051] n - is the number of turns of the enameled coil.

[0052] 3. Vibration of dynamic capacitance dynamic plate

[0053] The vibrating electrode and vibrator of the dynamic capacitor are fastened together with the electromagnetic suction piece. The electromagnetic suction piece vibrates under the action of the alternating electromagnetic force, and the dynamic plate of the dynamic capacitor will vibrate synchronously. The distance between the dynamic plate and the equilibrium position It can be expressed as:

[0054] (3)

[0055] Where:

[0056] - is the elastic coefficient of the vibrator, in N / m;

[0057] - is the mass of the vibrating electrode plus the electromagnetic suction piece, in kg.

[0058] 4. Modulation of DC current by vibration of moving plate

[0059] Current to be measured The resistance value is After the load is applied, a voltage drop is generated on the load. This voltage is applied to both ends of the dynamic capacitor. The dynamic capacitor will generate an AC signal due to the vibration of the dynamic plate. , whose value is:

[0060] (4)

[0061] Where:

[0062] - is the modulation factor, dimensionless, , obtained by calibration with a standard current source before the test.

[0063] 5. Calculation of DC current

[0064] When measuring the AC amplitude After that, it flows through the load The DC current can be calculated using formula (5):

[0065] (5)

[0066] The present invention is not limited to this embodiment, and all the contents of the present invention can be implemented and have the good effects.

Claims

1. A dynamic capacitor for direct current modulation, characterized in that: The dynamic capacitor comprises an insulator I (1), a fixed electrode (2), a vibrating electrode (3), a vibrator (4), an electromagnetic suction plate (5), a winding disk (6), an enameled coil (7), a housing (8), a grounding electrode (9), an insulator II (10), a coil positive electrode (11), a coil negative electrode (12) and a countersunk screw (13); The housing (8) is cylindrical, the left end of the housing (8) is a closed end, the insulator I (1) is fixedly mounted at the center of the left end of the housing (8), and the right end of the housing (8) is an open end; The fixed electrode (2) comprises a horizontal guide rod on the left and a vertical circular plate on the right, the horizontal guide rod penetrates into and is fastened to the center of the insulator I (1), and the vertical circular plate is located in the cavity of the housing (8); The vibrating electrode (3) has the same structure as the fixed electrode (2). The vibrating electrode (3) comprises a vertical circular electrode plate on the left and a horizontal guide rod on the right. The vibrating electrode (3) and the fixed electrode (2) are symmetrically placed. A gap is left between the vertical circular electrode plate of the vibrating electrode (3) and the vertical circular electrode plate of the fixed electrode (2). The electromagnetic suction plate (5) is fixed to the right end of the horizontal guide rod of the vibrating electrode (3). The surfaces of the vertical circular plates of the fixed electrode (2) and the vibrating electrode (3) are electroplated with a gold film with a thickness of 2 to 4 microns, and the surface roughness of the vertical circular plates is less than or equal to Ra0.2; The vibrator (4) comprises two vibrating plates, the horizontal guide rods of the vibrating electrodes (3) pass through the two vibrating plates in sequence and are fixed on the centers of the two vibrating plates, the two vibrating plates are located between the vertical circular pole plates of the vibrating electrodes (3) and the electromagnetic suction plates (5), and the upper and lower ends of each vibrating plate are fixed on the inner surface of the housing (8); The winding drum (6) has disks on the left and right sides and a round rod in the middle. A gap is left between the left disk of the winding drum (6) and the electromagnetic suction plate (5). An enameled coil (7) is evenly wound on the round rod of the winding drum (6). The right disk of the winding drum (6) is installed on the right end of the housing (8) and closes the right end of the housing (8) by countersunk screws (13) evenly distributed along the outer circumference. Two insulators II (10) are also installed on the right disk of the winding drum (6). The center of one insulator II (10) is fixed with a coil positive electrode (11), and the center of the other insulator II (10) is fixed with a coil negative electrode (12). The two ends of the enameled coil (7) are respectively welded to the left ends of the coil positive electrode (11) and the coil negative electrode (12). A grounding electrode (9) is also installed on the right disk of the winding drum (6). The right ends of the coil positive electrode (11) and the coil negative electrode (12) and the grounding electrode (9) are connected to an external power supply. The insulator I (1) and the insulator II (10) are made of ceramic, the fixed electrode (2) and the vibrating electrode (3) are made of 316L stainless steel, the vibrator (4), the electromagnetic suction plate (5) and the winding disk (6) are made of Permalloy, the shell (8) is made of electromagnetic pure iron, and the grounding electrode (9), the coil positive electrode (11) and the coil negative electrode (12) are made of brass.

2. The dynamic capacitor for DC current modulation according to claim 1, characterized in that: The inner and outer surfaces of the vibrator (4), the electromagnetic suction plate (5), the winding disk (6), and the outer shell (8) are all electroplated with a layer of gold film.

3. The dynamic capacitor for DC current modulation according to claim 1, characterized in that: The insulator I (1) and the insulator II (10) are fixed by sintering; the vibrator (4) and the electromagnetic suction piece (5) are fixed by welding.

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