Fusion sealing method for positive pressure filling glass air chamber based on low-temperature phase-change solder
Technical Field
The invention belongs to the technical field of atomic gas chamber manufacturing, and relates to a fusion sealing method for filling a glass gas chamber with positive pressure based on low-temperature phase-change solder.
Background
The high-pressure atomic gas chamber is a core component of an SERF gyroscope and an SERF magnetometer, and the performance of the atomic gas chamber directly influences the final precision of the instrument. To produce a more stable SERF state, the charge pressure in the atomic gas cell needs to reach several to tens of atmospheres to suppress spin-exchange collision relaxation of the polarized atoms to achieve extremely high sensitivity quantum precision measurements.
In order to reduce the adverse effect of stray light on signals, the high-pressure atomic gas chamber is mostly in a glass cubic/cylindrical structure. The general operation flow is that firstly, an air atom air chamber is vacuumized, then alkali metal and filling gas are filled, and finally, a high-temperature heating and glass-melting tube is used for completing the sealing of the atom air chamber. Wherein, the glass tube sealing process is mainly realized by the pressure difference between the atmospheric pressure and the glass tube. However, for a high-pressure atomic gas chamber (not less than 0.1MPa), when the glass tube is directly sintered, the sealing fails due to the fact that the pressure in the glass tube is higher than the atmospheric pressure and the glass tube is broken.
At present, the high-pressure atomic gas chamber is usually sealed by adopting a liquid nitrogen soaking mode: and cooling the gas in the gas chamber by using liquid nitrogen to reduce the pressure to be lower than 0.1MPa, and then burning and melting the glass tube to realize sealing. A disadvantage of this approach is that the liquid nitrogen temperature (-196 ℃) may cause partial filling gas (Xe) to liquefy or solidify, thereby causing a deviation in gas composition within the finished gas cell; the pressure in the air chamber is difficult to actively control by adopting a liquid nitrogen soaking method, and the pressure of the prepared air chamber is about 0.3MPa at most, so that the continuous improvement of the pressure of the air chamber is limited. Obviously, the liquid nitrogen soaking scheme is difficult to adapt to the requirements of precise control of gas components and higher pressure in the high-pressure atomic gas chamber.
Disclosure of Invention
The technical problem solved by the invention is as follows: the defects of the prior art are overcome, the sealing method for filling the glass air chamber with positive pressure based on the low-temperature phase-change solder is provided, the low-temperature solder pipe is used for plugging from the inside of the glass pipe, the sealing of the high-pressure atomic air chamber is realized on the premise of not burning the glass pipe, and the problem that the sealing of the high-pressure air chamber cannot be realized by directly burning the glass pipe can be solved.
The technical scheme of the invention is as follows:
a fusion sealing method for filling a glass gas chamber with positive pressure based on low-temperature phase-change solder comprises the following steps:
firstly, fixedly mounting a glass tube at the top of a glass gas chamber;
secondly, placing the welding material pipe into the glass pipe from the axial top end of the glass pipe;
step three, communicating the top of the glass tube with an external vacuum-pumping system; carrying out vacuum-pumping treatment on the glass air chamber through an external vacuum-pumping system;
filling a medium into the glass gas chamber from the axial top end of the glass tube; until the air pressure in the glass air chamber reaches a set air pressure value P;
step five, heating the solder tube to the phase transition temperature; sealing the through hole at the top of the glass gas chamber after the phase change of the solder tube;
step six, pumping out residual gas in the glass tube through an external vacuum pumping system;
and seventhly, sealing and fusing the glass tube to finish the preparation of the atomic gas chamber.
In the above fusion sealing method for filling a glass gas chamber with positive pressure based on a low-temperature phase-change solder, in the first step, a hollow cavity is arranged inside the glass gas chamber; the top of the glass air chamber is provided with a through hole; the glass tube is a hollow cylindrical structure; the glass tube is installed in alignment with the through hole.
In the fusion sealing method for filling the glass air chamber with positive pressure based on the low-temperature phase-change solder, the phase-change temperature of the solder tube is 50-600 ℃; the phase transition temperature of the solder tube is less than the softening temperature of the glass tube.
In the above fusion sealing method for filling a glass gas chamber with positive pressure based on a low-temperature phase-change solder, in the second step, the solder tube is in a hollow cylindrical structure; the outer diameter of the welding material pipe is smaller than the inner diameter of the glass pipe; the inner diameter of the welding material pipe is larger than the aperture of the through hole of the glass air chamber; the axial length of the welding material pipe is 2-3 times of the outer diameter of the welding material pipe; the solder pipe does not block the through hole of the glass air chamber.
In the above-mentioned fusion sealing method for filling a glass gas chamber under positive pressure based on a low-temperature phase-change solder, in the third step, after the vacuum-pumping treatment, the pressure of the glass gas chamber is less than 5 × 10-4Pa。
In the fourth step of the above fusion sealing method for filling a glass gas chamber with positive pressure based on low-temperature phase-change solder, the medium comprises alkali metal and inert gas; the inert gas is a mixed gas of xenon, neon and nitrogen.
In the fourth step of the above fusion sealing method for filling the glass gas chamber with positive pressure based on the low-temperature phase-change solder, the pressure value P is set to be 0.1-5 MPa.
Compared with the prior art, the invention has the beneficial effects that:
(1) when the method is adopted to seal the high-pressure atomic gas chamber by melting, the melting point of the low-temperature solder is lower, the glass gas chamber can be sealed at the temperature lower than the softening point of the glass material, and the problem that the high-pressure gas chamber cannot be sealed by directly burning and melting the glass tube is solved;
(2) when the method is adopted to seal the high-pressure atomic gas chamber by melting, the proportion and the components of the alkali metal and the filling gas in the gas chamber can be accurately controlled, and the pressure in the finished product gas chamber is higher and controllable (several to more than ten atmospheric pressures).
Drawings
FIG. 1 is a schematic view of the fusion sealing process of the present invention.
Detailed Description
The invention is further illustrated by the following examples.
The invention provides a method for sealing a high-pressure atomic gas chamber by melting, which is different from the traditional vacuum gas chamber in that the glass tube 2 is directly fused and connected by melting, the invention fills a section of low-temperature phase-change welding material tube 3 in the glass tube 2 connected with the glass gas chamber 1, completes the sealing of the gas chamber by heating and melting the welding material tube 3 after filling alkali metal and filling gas, then extracts the high-pressure gas in the glass tube 2, and heats the glass tube 2 by high temperature to perform secondary sealing and picking of the gas chamber. The atomic gas chamber prepared by the method has stable gas components and higher pressure.
As shown in FIG. 1, the fusion sealing method of the positive pressure filling glass air chamber mainly comprises the following steps:
firstly, fixedly mounting a glass tube 2 on the top of a glass gas chamber 1; a hollow cavity is arranged in the glass air chamber 1; the top of the glass air chamber 1 is provided with a through hole; the glass tube 2 is a hollow cylindrical structure; the glass tube 2 is mounted in alignment with the through hole. The phase change temperature of the welding material pipe 3 is 50-600 ℃; the phase transition temperature of the solder tube 3 is less than the softening temperature of the glass tube 2.
Secondly, placing the solder tube 3 into the glass tube 2 from the axial top end of the glass tube 2; the welding material pipe 3 is of a hollow cylindrical structure; the outer diameter of the welding material pipe 3 is smaller than the inner diameter of the glass pipe 2; the inner diameter of the welding material pipe 3 is larger than the aperture of the through hole of the glass air chamber 1; the axial length of the solder tube 3 is 2-3 times of the outer diameter of the solder tube 3; the solder tube 3 does not block the through hole of the glass air chamber 1.
Step three, communicating the top of the glass tube 2 with an external vacuum-pumping system; vacuumizing the glass air chamber 1 through an external vacuumizing system; after the vacuum-pumping treatment, the pressure of the glass gas chamber 1 is less than 5 multiplied by 10-4Pa。
Filling a medium into the glass gas chamber 1 from the axial top end of the glass tube 2; the medium comprises alkali metal and inert gas; the inert gas is a mixed gas of xenon, neon and nitrogen. Until the gas pressure in the glass gas chamber 1 reaches the set gas pressure value P. Setting the pressure value P to be 0.1-5 MPa.
Step five, heating the solder tube 3 to the phase transition temperature; sealing the through hole at the top of the glass air chamber 1 after the phase change of the welding material pipe 3;
step six, pumping out residual gas in the glass tube 2 through an external vacuum pumping system;
and seventhly, sealing and fusing the glass tube 2 to finish the preparation of the atomic gas chamber.
Examples
Realizing the fusion sealing of a high-pressure atomic gas chamber based on indium low-temperature phase change, comprising the following steps of:
(1) installing an indium solder tube: the solder tube 3 is made of indium with the melting point of 156 ℃, the outer diameter of the solder tube is slightly smaller than the inner diameter of the inflatable glass tube 2 connected with the glass gas chamber 1, the inner diameter of the solder tube 3 is slightly larger than the aperture of the filling hole of the glass gas chamber 1, and the length of the solder tube 3 is 2-3 times of the outer diameter of the solder tube. The welding material pipe 3 is filled in the inflatable glass pipe 2 connected with the glass air chamber 1 to the position above the air chamber filling hole, so that the glass air chamber filling hole is ensured not to be blocked;
(2) the glass gas chamber 1 is filled with alkali metal and inert gas: firstly, connecting an inflation glass tube of a glass gas chamber to a vacuum system, vacuumizing the glass gas chamber by using a vacuum pump until the pressure is less than 5 multiplied by 10 < -4 > Pa, and filling alkali metals (rubidium, cesium, potassium and the like) and inert gases (xenon, neon, nitrogen and the like) into the glass gas chamber according to a target proportion;
(3) heating causes the solder tube 3 to change phase: heating the area of the welding pipe 3 by flame or laser at 180-200 ℃ until indium melts and completely sealing the filling hole of the glass gas chamber 1;
(4) evacuating residual gas in the gas-filled glass tube 2 by using a vacuum pump;
(5) and (3) carrying out secondary sealing fusing on the inflatable glass tube 2 connected with the glass air chamber 1 by using flame or laser to prepare an atomic air chamber. It should be noted that, in the process of sealing the gas-filled glass tube 2 by melting, the heating area should be kept at a safe distance from the indium sealing position, so as to avoid the failure of melting and sealing the gas chamber caused by melting indium.
Although the present invention has been described with reference to the preferred embodiments, it is not intended to limit the present invention, and those skilled in the art can make variations and modifications of the present invention without departing from the spirit and scope of the present invention by using the methods and technical contents disclosed above.