Measuring device and method for measuring liquid level height of liquid metal on line

Abstract

The invention discloses a measuring device for measuring the liquid level height of liquid metal on line, and relates to the technical field of measuring devices.The device comprises a cesium crucible, the bottom of the cesium crucible is connected with a stainless steel cylindrical block, the top of the cesium crucible is provided with a crucible cover, and the crucible cover is connected with a connecting pipeline and a liquid metal liquid level probe; the other end of the connecting pipeline is connected with a safety valve, and a vacuum pipeline is arranged outside the liquid metal liquid level probe. The measuring device further comprises a resistance tester, the liquid metal liquid level probe is connected or disconnected with a High potential on the resistance tester, and the stainless steel cylindrical block is connected or disconnected with a Low potential on the resistance tester. By means of the measuring method of the device, whether the experiment cesium crucible contains enough liquid metal cesium or not can be judged on line, the number of times of disassembling the valve and the crucible can be reduced, abrasion of a clamping sleeve connector, the valve, a cesium crucible cover and a cesium crucible knife edge is reduced, and the problem that the cesium in the cesium crucible is oxidized due to the fact that the crucible is opened repeatedly for inspection is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of measuring devices, and in particular to a measuring device for online measuring the liquid metal level height and a measuring method thereof. Background Art

[0002] Magnetic confinement nuclear fusion has become one of the important solutions to human energy problems due to its unique rich raw materials, huge energy and inherent safety properties, and has attracted the attention of many developed and developing countries at home and abroad. However, in order to achieve fusion ignition conditions for magnetic confinement nuclear fusion, the conditions are very harsh, especially the core ion temperature needs to exceed 10keV. In order to achieve a core particle temperature of more than 10keV for magnetic confinement nuclear fusion, the negative ion source neutral beam injection system has become one of the focuses of magnetic confinement nuclear fusion research with its significant heating capacity. In the negative ion source neutral beam injection system, it is difficult to produce enough negative ions due to the high electron work function of the conventional metal surface. As the metal with the lowest surface work function, cesium has been used in the negative ion source neutral beam injection experiment.

[0003] Cesium, element symbol Cs, atomic number 55, low melting point, through the resistance wire heating, the liquid cesium in the crucible evaporates, cesium vapor enters the ion source, cesium deposited on the surface of the plasma electrode reduces the metal surface work function and increases the H- ion yield. Therefore, accurate monitoring of the content of metallic cesium in the cesium crucible is crucial to the normal operation of the negative ion source.

[0004] However, in the prior art, the measurement of the liquid cesium content in the cesium crucible during the negative ion source neutral beam injection experiment has the problems of low measurement accuracy and cumbersome routine operations, and the crucible needs to be opened for inspection; cesium is the most active alkali metal, which is easily oxidized in the air and can react violently with water to generate hydrogen and explode, so it is a hazardous chemical; and cesium metal is golden in color, and high-purity cesium is expensive. Failure to provide timely feedback on monitoring results will cause oxidation of the cesium metal in the crucible and other problems.

[0005] Online measurement systems usually have high measurement accuracy and flexibility, but there is still a lack of devices for online measurement of liquid metal level height, which leads to a lack of cesium residual data in negative ion source neutral beam injection experiments, affecting the stable operation of high-performance negative neutral beam experiments. Summary of the invention

[0006] The purpose of the present invention is to provide a measuring device and a measuring method for online measuring the liquid metal level height, so as to solve the following technical problems:

[0007] How to accurately monitor the amount of metallic cesium in a cesium crucible while avoiding cesium oxidation.

[0008] The purpose of the present invention can be achieved through the following technical solutions:

[0009] A measuring device for measuring the height of a liquid metal level online comprises a cesium crucible, a stainless steel cylindrical block is connected to the bottom of the cesium crucible, a crucible cover is provided on the top, a connecting pipe and a liquid metal level probe are connected to the crucible cover, wherein the other end of the connecting pipe is connected to a safety valve, and a vacuum pipe is provided outside the liquid metal level probe;

[0010] The measuring device also includes a resistance tester, wherein the liquid metal level probe is connected or disconnected to the High potential DRIVE interface and the SENSE interface on the resistance tester respectively through two High potential test wire clamps, and the stainless steel cylindrical block is connected or disconnected to the Low potential DRIVE interface and the SENSE interface on the resistance tester respectively through two Low potential test wire clamps.

[0011] In a further embodiment of the present invention: the crucible cover and the cesium crucible are both made of 304 stainless steel, and the inner side of the crucible cover and the inner side of the cesium crucible are respectively provided with corresponding knife edges, and the crucible cover and the cesium crucible are sealed by sealing copper gaskets arranged in the two knife edges; the crucible cover is also provided with two drill holes with apertures of 4.5 mm and 6.35 mm, respectively, for installing a liquid metal level probe and a connecting pipe, respectively.

[0012] In a further embodiment of the present invention, the connecting pipe is made of 304 stainless steel and has a length of 60 mm. One end of the connecting pipe is connected to the safety valve, and the other end is fixedly welded to the crucible cover through a drilled hole with a diameter of 6.35 mm on the crucible cover.

[0013] In a further embodiment of the present invention: the liquid metal level probe is made of 304 stainless steel and has a size of The probe is fixed and welded to the crucible cover through a hole with a diameter of 4.5 mm drilled on the crucible cover; the liquid metal level probe is first bent 90° and 4.5 mm at the crucible mouth of the cesium crucible, and then bent 90° downward, so that the liquid metal level probe is located in the center of the cesium crucible, and the liquid metal level probe is 1.3 mm away from the bottom of the cesium crucible.

[0014] In a further embodiment of the present invention: the vacuum pipe is welded and fixed to the upper part of the crucible cover. Stainless steel pipes, Ceramic pipes and The stainless steel pipe is spliced ​​by brazing technology. The liquid metal level probe is located inside the vacuum pipe and is welded and fixed to the top of the vacuum pipe, and the upper end exceeds the top of the vacuum pipe by 7.5 mm.

[0015] In a further embodiment of the present invention: the safety valve is a Swagelok SS-4BW high-temperature and high-pressure needle valve made of 316 stainless steel, and is provided with ferrule joints on both sides, one of which is sleeved with a connecting pipe, and the other ferrule joint is connected to an experimental device for injecting experimental metal and performing vacuum operation through a pipe.

[0016] In a further embodiment of the present invention, the interior of the cesium crucible is in the shape of a test tube, the top diameter of the cesium crucible is 34 mm, the inner wall diameter is 16 mm, the bottom radius is 8 mm, the depth is 68 mm, and 6 M4 screw holes are provided on the top for fixing the crucible cover with screws.

[0017] In a further embodiment of the present invention, the outer wall of the cesium crucible is provided with threads for rotating and fixing the heating copper ring.

[0018] In a second aspect, the present invention further discloses a measuring method for the measuring device for online measuring the liquid metal level height as described above, comprising the following steps:

[0019] S1. At temperature X℃, place the liquid metal level probe in contact with the bottom of the cesium crucible to form a loop. Use a resistance tester using advanced balanced bridge four-wire measurement technology to connect the liquid metal level probe and the stainless steel cylindrical block through the High potential test clip and the Low potential test clip to measure the resistance background R of the empty cesium crucible. 0 ;

[0020] S2. Disconnect the potential connection of the resistance tester, restore the liquid metal level probe to 1.3 mm from the bottom of the cesium crucible, operate in the glove box, fill the cesium crucible with the liquid metal cesium required for the experiment, record the height h of the liquid metal cesium when it is full, use the resistance tester to use the balanced bridge four-wire measurement technology, connect the liquid metal level probe and the stainless steel cylindrical block through the High potential test clip and the Low potential test clip, and measure the resistance value R of the cesium crucible when the height of the liquid metal cesium is h 1 ;

[0021] S3. When it is necessary to measure the content of liquid metal cesium in the cesium crucible, first heat the cesium crucible to X°C, then use a resistance tester to connect the liquid metal level probe and the stainless steel cylindrical block through the High potential test clip and the Low potential test clip using the balanced bridge four-wire measurement technology to measure the resistance value R of the cesium crucible when it is full of liquid metal cesium. t ;

[0022] S4. Calculate the liquid level height H of the liquid metal cesium. The calculation formula is: H = h[(R 0 -R t ) / (R 0 -R1 )].

[0023] In a further embodiment of the present invention: in step S3, the method for heating the cesium crucible to X°C is: first, the temperature of the heating copper ring of the cesium crucible is set to X°C for temperature adjustment, and the temperature is read by a constant temperature control device of the cesium crucible. When the temperature reaches X°C, the liquid metal level probe and the stainless steel cylindrical block at the bottom of the cesium crucible are leaked.

[0024] Beneficial effects of the present invention:

[0025] The present invention provides a simple and effective device for online measuring the liquid metal level height and a method for using the device, which can realize online judgment of whether a sufficient amount of liquid metal cesium is contained in an experimental cesium crucible, monitor the liquid metal cesium level in real time, and timely feedback the cesium level change, thereby ensuring the accuracy and reliability of the measurement result, and considering whether to dismantle the cesium crucible and whether to return to the glove box for replenishment according to the measured result; by reducing the number of times the valve and the crucible are disassembled, the wear of the ferrule joint, the valve, the cesium crucible cover and the cesium crucible blade is reduced, and the problem of oxidation of the metal cesium in the cesium crucible caused by opening the crucible for inspection many times is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] Figure 1 It is a structural schematic diagram of a measuring device for online measuring the liquid metal level height in the present invention.

[0028] In the figure: 1. Safety valve; 2. Connecting pipe; 3. Crucible cover; 4. Cesium crucible; 5. Stainless steel cylindrical block; 6. Vacuum pipe; 7. Liquid metal level probe; 8. High potential test wire clamp; 9. Low potential test wire clamp; 10. Resistance tester. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] Example 1

[0031] See also Figure 1The present invention discloses a measuring device for online measuring the liquid metal level height, comprising a safety valve 1, a connecting pipe 2, a crucible cover 3, a cesium crucible 4, a stainless steel cylindrical block 5, a vacuum pipe 6, a liquid metal level probe 7, a High potential test clip 8, a Low potential test clip 9, and a resistance tester 10.

[0032] The cesium crucible 4 is made of 304 stainless steel, the interior of the cesium crucible 4 is in the shape of a test tube, and the top diameter of the cesium crucible 4 is The inner diameter is The bottom radius is 8mm, and the depth is divided into two parts, one part is a cylinder with a depth of 60mm and a diameter of 16mm, and the other part is a hemisphere with a radius of 8mm, and the two parts are connected up and down in sequence. The outer wall of the cesium crucible 4 has a trapezoidal thread, which is convenient for rotating and fixing the heating copper ring, achieving the effect of heating and heat preservation.

[0033] The crucible cover 3 is installed on the top of the cesium crucible 4, and the crucible cover 3 is made of 304 stainless steel; the inner side of the crucible cover 3 and the inner side of the top of the cesium crucible 4 are provided with knife edges that correspond to each other, and sealing copper gaskets are provided in the two knife edges, so that the lid 3 and the cesium crucible 4 are sealed with each other to achieve vacuum experimental conditions; the top of the cesium crucible 4 is provided with 6 screw holes of size m4, and the crucible cover 3 is fixed to the cesium crucible 4 through the screw holes with bolts. The crucible cover 3 is also provided with two drill holes with apertures of 4.5mm and 6.35mm respectively, and the two drill holes are respectively 2.25mm and 1.3mm away from the center of the cesium crucible cover 3.

[0034] The connecting pipe 2 is made of 304 stainless steel and has a length of 60 mm. The lower end of the connecting pipe 2 is fixedly welded to the drilled hole with a hole diameter of 6.35 mm on the crucible cover 3 by welding; the upper end is connected to the high temperature resistant safety valve 1, which is a Swagelok SS-4BW high temperature and high pressure needle valve made of 316 stainless steel, and has ferrule joints on both sides, one of which is sleeved with the upper end of the connecting pipe 2, and the other ferrule is connected to the experimental device for injecting experimental metal and performing vacuum operation through a pipeline, so as to inject or extract liquid metal into the cesium crucible.

[0035] The liquid metal level probe 7 is made of 304 stainless steel and has a size of The liquid metal level probe 7 is fixedly welded to the drilled hole with a hole diameter of 4.5 mm on the crucible cover 3 by welding; the liquid metal level probe 7 is first bent 90° and 4.5 mm at the crucible mouth inside the cesium crucible 4, and then bent 90° downward, so that the liquid metal level probe 7 is located in the center of the cesium crucible, and the liquid metal level probe 7 is 1.3 mm away from the bottom of the cesium crucible 4, and remains disconnected.

[0036] It should be noted that the angle of the liquid metal level probe 7 can be adjusted at two bends, so as to control the distance between the lower end of the liquid metal level probe 7 and the bottom of the cesium crucible 4 .

[0037] The vacuum pipe 6 is connected from top to bottom. Stainless steel pipes, Ceramic pipes and The stainless steel pipes are spliced ​​together by brazing technology for use in a vacuum environment; the bottom stainless steel pipe is welded and fixed to the upper side of the crucible cover 3, the liquid metal level probe 7 is passed through the vacuum pipe 6 and welded to the top of the vacuum pipe 6, and the welding position exceeds the stainless steel pipe at the top of the vacuum pipe 6 by 10.7 mm.

[0038] The resistance tester 10 uses the HL2515 DC low resistance tester, which is provided with a High potential DRIVE and SENSE interface and a Low potential DRIVE and SENSE interface. There are two High potential test clamps 8, one end of the two High potential test clamps 8 are respectively connected to the High potential DRIVE and SENSE interface, and the other end can be clamped and fixed on the upper position of the liquid metal level probe 7; there are two Low potential test clamps 9, one end of the two Low potential test clamps 9 are respectively connected to the Low potential DRIVE and SENSE interface, and the other end can be clamped and fixed on the stainless steel cylindrical block 5 installed at the bottom of the cesium crucible 4.

[0039] It should be noted that the specific model of the resistance tester 10 is not limited to the HL2515 DC low resistance tester in this embodiment. In other embodiments, a resistance tester with the same effect can also be selected.

[0040] Example 2

[0041] This embodiment discloses a measuring method for the measuring device for online measuring the liquid metal level height as described in Embodiment 1, wherein the test temperature is 30° C. and includes the following steps:

[0042] S1. At 30°C, adjust the bend of the liquid metal level probe 7 so that its lower end contacts the bottom of the cesium crucible 4 to form a loop. Use a resistance tester 10 using advanced balanced bridge four-wire measurement technology to connect the liquid metal level probe 7 and the stainless steel cylindrical block 5 through the High potential test clip 8 and the Low potential test clip 9 to measure the resistance background R of the empty cesium crucible 4 (the height of the liquid metal cesium is 0). 0 ;

[0043] S2. Disconnect the potential connection of the resistance tester 10, reset the bend of the liquid metal level probe 7, so that the lower end of the liquid metal level probe 7 is restored to 1.3 mm from the bottom of the cesium crucible 4, operate through the glove box, fill the cesium crucible 4 with the liquid metal cesium required for the experiment, record the height h of the liquid metal cesium when it is full, use the resistance tester 10 to use the balanced bridge four-wire measurement technology, connect the liquid metal level probe 7 and the stainless steel cylindrical block 5 through the High potential test clamp 8 and the Low potential test clamp 9, and measure the resistance value R of the cesium crucible 4 when the height of the liquid metal cesium is h. 1 ;

[0044] S3. When it is necessary to measure the content of liquid metal cesium in the cesium crucible 4, first heat the cesium crucible 4 to 30°C, then use the resistance tester 10 to connect the liquid metal level probe 7 and the stainless steel cylindrical block 5 through the High potential test clamp 8 and the Low potential test clamp 9, and measure the resistance value R of the cesium crucible 4 when it is full of liquid metal cesium. t ;

[0045] S4. Calculate the liquid level height H of the liquid metal cesium. The calculation formula is: H = h[(R 0 -R t ) / (R 0 -R 1 )].

[0046] Further, in step S3, the method for heating the cesium crucible 4 to 30°C is as follows: first, the temperature of the heating copper ring of the cesium crucible 4 is set to 30°C for temperature adjustment, and the temperature is read by the constant temperature control device of the cesium crucible 4. When the temperature reaches 30°C, the liquid metal level probe 7 and the stainless steel cylindrical block 5 at the bottom of the cesium crucible 4 are leaked out to facilitate the connection of the circuit.

[0047] It should be noted that the balanced bridge four-wire measurement technology is an existing technology, so its principle will not be described in detail here.

[0048] The working principle of the measurement method is: use two test lines to pass a constant current through the connector contact resistance to convert the resistance signal into a voltage signal, and then test the voltage at both ends of the connector contact resistance through the two test lines. The voltage value is not affected by the four-wire conductor resistance and the contact resistance, thereby achieving high-precision measurement, judging whether the cesium crucible 4 contains a sufficient amount of liquid metal cesium during the experiment, and considering whether to remove the cesium crucible 4 and whether it is necessary to return to the glove box for replenishment of liquid metal cesium based on the measured results, thereby reducing the number of times the safety valve 1 and the cesium crucible 4 are disassembled, reducing the wear of the ferrule joint, the safety valve 1, the cesium crucible cover 3 and the blade of the cesium crucible 4, and avoiding the problems of oxidation of the metal cesium in the cesium crucible 4 caused by opening the cesium crucible 4 for inspection multiple times.

[0049] In the description of the present invention, it should be understood that the terms "upper", "lower", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction and a specific direction structure and operation, and therefore, cannot be understood as a limitation on the present invention. In addition, "first" and "second" are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0050] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A measuring device for online measuring the liquid metal level height, characterized in that: The cesium crucible (4) comprises a stainless steel cylindrical block (5) connected to the bottom of the cesium crucible (4) and a crucible cover (3) on the top, the crucible cover (3) being connected to a connecting pipe (2) and a liquid metal level probe (7), wherein the other end of the connecting pipe (2) is connected to a safety valve (1), and a vacuum pipe (6) is installed outside the liquid metal level probe (7); The measuring device further comprises a resistance tester (10); the liquid metal level probe (7) is connected or disconnected to a high potential DRIVE interface and a SENSE interface on the resistance tester (10) respectively via two high potential test wire clamps (8); and the stainless steel cylindrical block (5) is connected or disconnected to a low potential DRIVE interface and a SENSE interface on the resistance tester (10) respectively via two low potential test wire clamps (9).

2. The device for measuring the liquid metal level online according to claim 1, characterized in that: The crucible cover (3) and the cesium crucible (4) are both made of 304 stainless steel, and the inner side of the crucible cover (3) and the inner side of the cesium crucible (4) are respectively provided with knife edges corresponding to each other, and the crucible cover (3) and the cesium crucible (4) are sealed by sealing copper gaskets arranged in the two knife edges; the crucible cover (3) is also provided with two drill holes with apertures of 4.5 mm and 6.35 mm, respectively, for installing a liquid metal level probe (7) and a connecting pipe (2), respectively.

3. The device for measuring the liquid metal level online according to claim 2, characterized in that: The connecting pipe (2) is made of 304 stainless steel and has a length of 60 mm. One end of the connecting pipe (2) is connected to the safety valve (1), and the other end is fixedly welded to the crucible cover (3) through a drilled hole with a hole diameter of 6.35 mm on the crucible cover (3).

4. The device for measuring the liquid metal level online according to claim 2, characterized in that: The liquid metal level probe (7) is made of 304 stainless steel and has a size of The liquid metal level probe (7) is fixedly welded to the crucible cover (3) through a hole drilled on the crucible cover (3) with a hole diameter of 4.5 mm; the liquid metal level probe (7) is first bent 90° and 4.5 mm at the crucible mouth of the cesium crucible (4), and then bent 90° downward, so that the liquid metal level probe (7) is located in the center of the cesium crucible (4), and the liquid metal level probe (7) is 1.3 mm away from the bottom of the cesium crucible (4).

5. The device for measuring the liquid metal level online according to claim 4, characterized in that: The vacuum pipe (6) is welded and fixed to the upper part of the crucible cover (3). Stainless steel pipes, Ceramic pipes and The stainless steel pipe is spliced ​​by brazing technology. The liquid metal level probe (7) is located inside the vacuum pipe (6) and is welded and fixed to the top of the vacuum pipe (6), and the distance between the upper end and the top of the vacuum pipe (6) is 7.5 mm.

6. The device for measuring the liquid metal level online according to claim 1, characterized in that: The safety valve (1) is a Swagelok SS-4BW high-temperature and high-pressure needle valve made of 316 stainless steel, and is provided with ferrule joints on both sides, one of which is sleeved with the connecting pipe (2), and the other ferrule joint is connected to the experimental device for injecting test metal and performing vacuum operation through a pipe.

7. The device for measuring the liquid metal level online according to claim 1, characterized in that: The interior of the cesium crucible (4) is in the shape of a test tube, with a top diameter of 34 mm, an inner wall diameter of 16 mm, a bottom radius of 8 mm, a depth of 68 mm, and 6 M4 screw holes on the top for fixing the crucible cover (3) with screws.

8. The device for measuring the liquid metal level online according to claim 7, characterized in that: The outer wall of the cesium crucible (4) is provided with a thread for rotating and fixing the heating copper ring.

9. A measuring method for measuring the liquid metal level online according to any one of claims 1 to 8, characterized in that: The steps include: S1. At a temperature of X°C, a liquid metal level probe (7) is brought into contact with the bottom of a cesium crucible (4) to form a loop. A resistance tester (10) is used to connect the liquid metal level probe (7) and a stainless steel cylindrical block (5) via a high potential test clamp (8) and a low potential test clamp (9) to measure the resistance background R0 of an empty cesium crucible (4). S2, disconnect the potential connection of the resistance tester (10), restore the liquid metal level probe (7) to a position 1.3 mm away from the bottom of the cesium crucible (4), operate in a glove box, fill the cesium crucible (4) with the liquid metal cesium required for the experiment, record the height h of the liquid metal cesium when it is full, use the resistance tester (10) to use the balanced bridge four-wire measurement technology, connect the liquid metal level probe (7) and the stainless steel cylindrical block 5 through the High potential test clamp (8) and the Low potential test clamp (9), and measure the resistance value R1 of the cesium crucible (4) when the height of the liquid metal cesium is h; S3. When it is necessary to measure the content of liquid metal cesium in the cesium crucible 4, first heat the cesium crucible (4) to X°C, then use a resistance tester (10) using a balanced bridge four-wire measurement technique to connect the liquid metal level probe (7) and the stainless steel cylindrical block (5) through a high potential test clamp (8) and a low potential test clamp (9), and measure the resistance value R of the cesium crucible (4) when it is filled with liquid metal cesium. t ; S4. Calculate the liquid level height H of the liquid metal cesium. The calculation formula is: H = h [(R0-R t ) / (R0-R1)].

10. The measuring method of the measuring device for online measuring the liquid metal level height according to claim 9, characterized in that: In step S3, the method for heating the cesium crucible (4) to X°C is as follows: first, the temperature of the heating copper ring of the cesium crucible (4) is set to X°C for temperature adjustment, and the temperature is read by a constant temperature control device of the cesium crucible (4). When the temperature reaches X°C, the liquid metal level probe (7) and the stainless steel cylindrical block (5) at the bottom of the cesium crucible (4) leak out.

Images