A portable microcurrent constant current source device

Abstract

The present invention belongs to the field of ionizing radiation measurement, and discloses a portable micro-current constant current source device, which includes a spherical ionization chamber. The spherical ionization chamber includes a spherical metal shell and a collecting electrode located inside the spherical metal shell. The spherical metal shell is provided with a high-voltage electrode sealing interface. The outer side of the spherical metal shell is coated with an insulating coating. An incident window is opened at the bottom of the spherical metal shell. A radiation source box is provided at the bottom of the spherical metal shell. A radiation source facing the incident window is installed in the radiation source box. An F4 insulator is installed at the top of the spherical metal shell; the collecting electrode includes a first collecting ring, a second collecting ring and a current output terminal. The first collecting ring and the second collecting ring are connected at right angles. The top of the first collecting ring is connected to the current output terminal, and the current output terminal is led out from the center of the F4 insulator. This micro-current constant current source device can provide a stable current output.

Description

Technical Field

[0001] The present invention relates to the field of ionizing radiation measurement, and particularly to a portable micro-current constant current source device. Background Art

[0002] With the development of science and technology, there are DC micro-current signals in industrial fields such as aerospace, nuclear industry, and ordnance in China, in the fields of electrical and ionizing radiation measurement, as well as in scientific research and teaching experiments. For example, in the research on spacecraft surface charging, it is necessary to measure a micro-current of 10 -4 -10 -11 A. In the 4πγ high-pressure ionization chamber radionuclide activity measurement standard device used in the nuclear industry, it is necessary to measure a micro-current of 10 -12 A. Micro-current electroanalytical instruments are widely used in analytical chemistry, life science, and bioelectrochemistry, with a micro-current measurement range of 10 -5 -10 -11 A. There are also measurements of the dark current of vacuum optoelectronic devices and photomultiplier tubes, as well as measurements of bioelectric current, Hall effect testing, and measurement of the resistance value of high-value resistance elements. All of the above various test instruments require a standard DC micro-current as input for calibration and verification.

[0003] Current DC micro-current constant current sources include resistive DC micro-current constant current sources, capacitive DC micro-current constant current sources, and ionization-type DC micro-current sources, with an output current of 10 -6 -10 -10 A. They have poor long-term stability of low current, a small internal resistance of the current source, and cannot meet the metrological calibration of electrometer-type micro-current meters. There is a method of using X-ray irradiation of an ionization chamber to achieve single-range micro-current output, but the device is fixed and cannot be moved, the range is not wide enough, and it is difficult to solve radiation protection, so it is not practical in the field of electrical calibration. Summary of the Invention

[0004] The present invention aims to provide a portable micro-current constant current source device to ensure stable output of micro-current.

[0005] To achieve the above object, the present invention provides the following technical solution:

[0006] A portable micro-current constant current source device includes a spherical ionization chamber. The spherical ionization chamber includes a spherical metal shell and a collecting electrode located inside the spherical metal shell. The spherical metal shell is provided with a high-voltage electrode sealing interface. The outer side of the spherical metal shell is coated with an insulating coating. An incident window is opened at the bottom of the spherical metal shell. A radiation source box is provided at the bottom of the spherical metal shell. A radiation source facing the incident window is installed in the radiation source box. An F4 insulator is installed at the top of the spherical metal shell. The collecting electrode includes a first collecting ring, a second collecting ring, and a current output terminal. The first collecting ring and the second collecting ring are cross-connected at a right angle. The top of the first collecting ring is connected to the current output terminal. The current output terminal is led out from the center of the F4 insulator.

[0007] Further, two pure aluminum sheets are horizontally inserted into one side of the radiation source box. The pure aluminum sheets are blocked between the radiation source box and the incident window. The interval between the two pure aluminum sheets is less than 2 mm. The interval between the pure aluminum sheet close to the radiation source and the radiation source is less than 2 mm. The thicknesses of the two pure aluminum sheets are 0.5 mm and 3 mm respectively.

[0008] The beneficial effects of the present invention are as follows:

[0009] The spherical ionization chamber of the present invention is an atmospheric pressure sealed ionization chamber. The inside of it is dry air at atmospheric pressure. Using long-life 90 Sr+ 90 Yβ nuclides ionize the air in the spherical ionization chamber. Apply an 800V constant DC voltage between the collecting electrode and the spherical metal shell. Then the ionized ions form a stable DC current under the action of the electric field. And two pure aluminum sheets with different thicknesses are set in the radiation source box to change the beta particle emission rate to adjust the current magnitude generated by the spherical ionization chamber.

[0010] The present invention uses two uniquely cross-connected at a right angle collecting rings to collect ionized ions, improving the collection efficiency of ionized ions; the sealed ionization chamber and the long half-life 90 Sr+ 90 Yβ radiation source ensure stable current output. This current is between 10 -10 ~10 -13 A. The stability in 8 hours is better than 0.05%, and the long-term stability is better than 0.2%; also, because the space between the two poles of the spherical ionization chamber is dry air and polytetrafluoroethylene insulation, therefore, in addition to the stable characteristics, the output micro-current also has an extremely high internal resistance, that is, the internal resistance of the current source is greater than 5×10 13 Ω, and the conventional laboratory environment has no influence on the output current.

[0011] 90 Sr+ 90Yβ is easy to protect. This device can be widely used in electrical and ionization radiation laboratories for the calibration and performance experiments of electrometer-type microammeters. Also, due to its sealed structure and insulating coating design, it is convenient to carry. Brief Description of the Drawings

[0012] Figure 1 It is a schematic structural diagram of a portable microcurrent constant current source device provided by an embodiment of the present invention;

[0013] The reference numerals in the figure include: 1, spherical metal shell; 2, collecting electrode; 21, first collecting ring; 22, second collecting ring; 23, current output terminal; 3, high-voltage electrode sealing interface; 4, radioactive source box; 5, pure aluminum sheet; 6, incident window; 7, F4 insulator. Detailed Embodiments

[0014] The present invention will be further described in detail below with reference to the drawings and embodiments:

[0015] As Figure 1 shown, a portable microcurrent constant current source device based on 90 Sr+ 90 Yβ ray air ionization includes a spherical ionization chamber. The spherical ionization chamber includes a spherical metal shell 1 and a collecting electrode 2 located inside the spherical metal shell 1. The spherical metal shell 1 is provided with a high-voltage electrode sealing interface 3. The outer side of the spherical metal shell 1 is coated with an insulating coating. An incident window 6 is opened at the bottom of the spherical metal shell 1. A radioactive source box 4 is provided at the bottom of the spherical metal shell 1. A radioactive source facing the incident window 6 is installed in the radioactive source box 4. Two pure aluminum sheets 5 are horizontally inserted on one side of the radioactive source box 4. The pure aluminum sheets 5 are blocked between the radioactive source box 4 and the incident window 6. The interval between the two pure aluminum sheets 5 is less than 2 mm. The interval between the pure aluminum sheet 5 close to the radioactive source and the radioactive source is less than 2 mm. The thicknesses of the two pure aluminum sheets 5 are 0.5 mm and 3 mm respectively. The thickness can also be adjusted to change the absorption ratio of β rays, thereby adjusting the output current of the current source. An F4 insulator 7 is installed at the top of the spherical metal shell 1. The collecting electrode 2 includes a first collecting ring 21, a second collecting ring 22 and a current output terminal 23. The first collecting ring and the second collecting ring 22 are connected at right angles. The top of the first collecting ring 21 is connected to the current output terminal 23. The current output terminal 23 is led out from the center of the F4 insulator 7.

[0016] Using the long-lived 90 Sr+ 90 Yβ nuclide as the radioactive source, emitting β rays and entering the spherical ionization chamber through the incident window 6. A constant DC voltage of 800 V is applied between the collecting electrode 2 and the spherical ionization outer shell. Then, the ionized ions form a stable DC current under the action of the electric field. The current output terminal 23 outputs a stable microcurrent for calibrating and examining the stability of extremely low current measuring instruments. Among them, the long-term current change can be corrected by the half-life:

[0017] I = I0×e (T / 2×28.7)

[0018] I: The current at time T

[0019] I0: The initial current

[0020] T: The time from the initial moment to the time when the current is measured, in years.

[0021] 90 Sr+ 90 The half-life of the Yβ nuclide is 28.7 years.

[0022] The above are only embodiments of the present invention. Specific technical solutions and / or common knowledge such as characteristics well known in the art are not described in detail herein. It should be noted that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners described in the specification can be used to interpret the content of the claims.

Claims

1. A portable micro-current constant current source device, comprising a spherical ionization chamber, wherein the spherical ionization chamber includes a spherical metal outer shell (1) and a collecting electrode (2) located inside the spherical metal outer shell (1), and is characterized in that: The spherical metal shell (1) is provided with a high-voltage pole sealing interface (3). The outer side of the spherical metal shell (1) is coated with an insulating coating. An incident window (6) is opened at the bottom of the spherical metal shell (1). A radiation source box (4) is arranged at the bottom of the spherical metal shell (1). A radiation source facing the incident window (6) is installed in the radiation source box (4). An F4 insulator (7) is installed at the top of the spherical metal shell (1). The collector electrode (2) includes a first collector ring (21), a second collector ring (22) and a current output terminal (23). The first collector ring and the second collector ring (22) are connected in a right-angle cross manner. The top of the first collector ring (21) is connected to the current output terminal (23). The current output terminal (23) is led out from the center of the F4 insulator (7).

2. The portable micro-current constant current source device according to claim 1, wherein: Two pure aluminum sheets (5) are horizontally inserted into one side of the radiation source box (4). The pure aluminum sheets (5) are blocked between the radiation source box (4) and the incident window (6). The interval between the two pure aluminum sheets (5) is less than 2 mm. The interval between the pure aluminum sheet (5) close to the radiation source and the radiation source is less than 2 mm. The thicknesses of the two pure aluminum sheets (5) are 0.5 mm and 3 mm respectively.

Images