RU228239U1 - Sealed neutron tube - Google Patents

Abstract

The utility model relates to sealed neutron tubes and can be used in neutron generators for studying geophysical and production wells, for neutron radiation therapy, as well as for modeling neutron fields of thermonuclear devices. The technical result is an increase in the neutron flux of the tube. The technical result is achieved in that the sealed neutron tube, the neutron tube containing a hollow cylindrical insulator, at one end of which the target is hermetically fixed, at the other end a grounded metal housing of the ion source, which is the anode, made in the form of a glass, the walls of which are covered along their outer diameter by a cylindrical permanent magnet, in the glass on the inside of the bottom axially to it is placed a cathode; on the opposite side of the glass facing the target, an anticathode with a central hole for extracting ions is placed axially to it, the cathode and anticathode are insulated from the grounded metal body, the opposite surfaces of the bottom of the glass and the cathode are oxidized, the cathode is tightly pressed to the bottom of the glass through oxide layers of minimum thickness sufficient to ensure electrical strength; wherein the bottom of the glass is made of a soft magnetic material and is tightly covered along the diameter by a ring made of a soft magnetic material; the end of the ring is connected to the end of a cylindrical permanent magnet. 2 fig.

Description

The utility model relates to sealed neutron tubes and can be used in neutron generators for studying geophysical and production wells, for radiation neutron therapy, and also for modeling neutron fields of thermonuclear devices.

A sealed neutron tube is known, containing a hollow cylindrical insulator, at one end of which a target is hermetically secured, and at the other end of which a metal housing is hermetically secured, located in the cavity of a cylindrical permanent magnet, with a cathode and anticathode located in it, connected to the housing, and a ring anode, isolated from the housing (Patent of the Russian Federation No. 2540983, IPC H05H 3/06, 10.02.2015).

The disadvantage of the known device is the low efficiency of gas ionization in the area of the gas discharge chamber, limited by the anode, cathode and anticathode, and as a consequence, the low value of the neutron flux, due to the low value of magnetic induction on the inner surface of the anode, since the anode is isolated from the housing, is located at a distance from the surface of the magnet, and the magnetic induction quickly decreases from the inner surface of the magnet to the center.

The permanent magnet in the known device is placed at a distance from the anode, since they are under different potentials. This does not allow increasing the magnetic field intensity on the anode surface. In addition, the analog excludes the possibility of increasing the anode diameter without increasing the dimensions of the entire sealed neutron tube.

A sealed neutron tube is known, containing a hollow cylindrical insulator, at one end of which a target is hermetically secured (Fig. 1). At the end of the hollow cylindrical insulator opposite to the target, a metal housing of the ion source is hermetically secured, which is the anode, made in the form of a glass, the walls of which are embraced along their outer diameter by a cylindrical permanent magnet, in the glass on the bottom side a cathode is placed axially to it; on the opposite side of the glass facing the target, an anticathode with a central hole for extracting ions is placed axially to the glass (Patent of the Russian Federation No. 2356114, IPC G21G 4/02, 20.05.2009). This technical solution is adopted as a prototype.

The disadvantage of the prototype is the low value of the tube neutron flux due to the low efficiency of gas ionization in the gas discharge chamber.

Magnetic induction in the gas discharge chamber is created by a cylindrical permanent magnet.

Due to the absence of a magnetic circuit connecting the end of the magnet and the cathode, the magnetic lines of force are not concentrated in the volume of the ion source. Some of the magnetic lines of force are closed outside the volume of the source. Between the cathode and the anode there is a gap necessary to ensure electrical strength, the sufficient size of which is usually less than 1 mm. In order to prevent a violation of the electrical strength of the gap between the bottom of the cup (anode) and the cathode due to even a slight violation of the coaxiality of the cathode and the cup during the operation of the device, the cathode is removed from the anode at a greater distance. While maintaining the dimensions of the devices, this reduces the volume of the gas-discharge chamber and leads to an additional increase in the magnetic resistance of the gap between the anode and the cathode.

The above mentioned disadvantages reduce the magnetic field intensity on the inner surface of the anode and on the cathode. The efficiency of gas ionization in the discharge decreases, which leads to a decrease in the extracted ion current and to a decrease in the neutron flux.

The proposed technical solution eliminates this drawback.

The technical result is an increase in the tube neutron flux.

The technical result is achieved in that a sealed neutron tube containing a hollow cylindrical insulator, at one end of which a target is hermetically secured, at the other end a grounded metal housing of the ion source, which is the anode, made in the form of a cup, the walls of which are embraced along their outer diameter by a cylindrical permanent magnet; in the cup, on the inner side of the bottom, a cathode is placed axially to it; on the opposite side of the cup facing the target, an anticathode with a central hole for extracting ions is placed axially to it; the cathode and anticathode are insulated from the grounded metal housing, the opposite surfaces of the bottom of the cup and the cathode are oxidized, the cathode is tightly pressed to the bottom of the cup through oxide layers of a minimum thickness sufficient to ensure the electrical strength of the gap between the bottom of the cup and the cathode; wherein the bottom of the cup is made of a soft magnetic material and is tightly embraced along the diameter by a ring made of a soft magnetic material; the end of the ring is connected to the end of a cylindrical permanent magnet.

The essence of the utility model is explained by the drawing:

Fig. 2 shows a schematic representation of a sealed neutron tube, where:

1 - hollow cylindrical insulator;

2 - target;

3 - oxide layers;

4 - cathode;

5 - anticathode with a central hole for extracting ions;

6 - cylindrical permanent magnet;

7 - glass;

8 - ring made of soft magnetic material.

The device comprises a hollow cylindrical insulator 1, at one end of which a target 2 is hermetically fixed. At the other end, a grounded metal housing of the ion source is hermetically fixed, which is the anode, made in the form of a cup 7. The walls of the cup 7 are embraced along their outer diameter by a cylindrical permanent magnet 6. In the cup 7, on the inner side of the bottom, a cathode 4 is axially placed to it. On the opposite side of the cup 7 facing the target 2, an anticathode 5 is axially placed to it with a central hole for extracting ions. The cathode 4 and the anticathode 5 are insulated from the grounded metal housing. The opposite surfaces of the bottom of the cup 7 and the cathode 4 are oxidized. The cathode 4 is tightly pressed to the bottom of the glass 7 through oxide layers 3 of minimum thickness, ensuring the electrical strength of the gap between the bottom of the glass 7 and the cathode 4. The bottom of the glass 7 is made of a soft magnetic material and is tightly covered by a ring 8 along the diameter, made of a soft magnetic material. The end of the ring 8 is connected to the end of the cylindrical permanent magnet 6.

The device works as follows.

An accelerating voltage is applied to target 2 relative to cup 7. A negative voltage is applied to cathode 4 and anticathode 5 of the ion source relative to grounded cup 7.

The cylindrical permanent magnet 6 creates a magnetic field that is concentrated in the volume of the glass 7 (the ion source) through the ring 8 made of a soft magnetic material and the bottom of the glass 7 made of a soft magnetic material. To reduce magnetic resistance, the ring 8 tightly covers the bottom of the glass 7.

The cathode 4 is tightly pressed to the bottom of the glass 7 through oxide layers 3 of minimum thickness, providing the electric strength of the gap between the bottom of the glass 7 and the cathode 4. A decrease in the distance in vacuum (between the bottom of the glass 7 and the cathode 4) leads to an increase in the magnetic induction at the surface of the cathode 4. The presence of an electric and magnetic field ensures the ignition of a gas discharge in the ion source. The concentration of magnetic field lines on the surface of the cathode 4 increases, the magnetic field strength at the inner surface of the anode increases. Through an opening in the anticathode 5, ions from the discharge enter the volume of the hollow cylindrical insulator 1 and are accelerated to the target 2. Neutrons are formed in the target 2 as a result of thermonuclear reactions. The decrease in magnetic induction from the cathode 4 to the anticathode 5 due to the concentration of magnetic lines of force at the cathode 4 facilitates the expulsion of the gas discharge plasma to the hole in the anticathode 5. This leads to an increase in the number of ions extracted from the source and accelerated onto the target 2 and to an increase in the neutron flux.

Thus, the stated technical result is achieved, namely, an increase in the tube neutron flux.

Claims (1)

A sealed neutron tube containing a hollow cylindrical insulator, at one end of which a target is hermetically secured, at the other end of which a grounded metal housing of an ion source is hermetically secured, which is the anode, made in the form of a cup, the walls of which are embraced along their outer diameter by a cylindrical permanent magnet; in the cup, on the inside of the bottom, a cathode is placed axially to it; on the opposite side of the cup facing the target, an anticathode with a central hole for extracting ions is placed axially to it; the cathode and anticathode are insulated from the grounded metal housing, characterized in that the opposite surfaces of the bottom of the cup and the cathode are oxidized, the cathode is tightly pressed to the bottom of the cup through oxide layers of a minimum thickness sufficient to ensure the electric strength of the gap between the bottom of the cup and the cathode; wherein the bottom of the cup is made of a soft magnetic material and is tightly embraced along the diameter by a ring made of a soft magnetic material; the end of the ring is connected to the end of a cylindrical permanent magnet.