In-situ atmosphere reaction grazing incidence experimental device

Abstract

The invention relates to an in-situ atmosphere reaction grazing incidence experiment device which comprises a position adjusting device, a temperature changing device and a gas reaction device, the temperature changing device is arranged on the position adjusting device, and the gas reaction device is fixed on the temperature changing device; the temperature changing device comprises a first shell, a cold and hot element and a cover body, the first shell is provided with a first inner cavity, the gas reaction device comprises a second shell, a covering element and an emergent window, the second shell defines a second inner cavity provided with an incident opening and an emergent opening, the covering element covers the incident opening, the covering element is provided with a light inlet channel for X-rays to pass through, and the emergent window is provided with a light outlet. The emergent window covers the emergent opening; the cold and hot element and the cover body are both located in the second inner cavity, the cover body is fixedly connected with the second shell and covers the cold and hot element, the cover body is used for supporting the sample, and the cold and hot element keeps in contact with the cover body so as to change the temperature of the cover body and the sample; and a vent hole for introducing reaction gas into the second inner cavity is formed in the second shell.

Description

Technical Field

[0001] The invention relates to the technical field of X-ray grazing incidence experimental devices, and more specifically to an in-situ atmosphere reaction grazing incidence experimental device. Background Art

[0002] Synchrotron radiation X-ray grazing incidence diffraction and scattering testing technology is an important means to study the microstructure of thin film materials or material surfaces and their evolution laws. Some materials will be corroded in environments such as hydrogen, water vapor, oxygen, chlorine, methane, carbon monoxide, etc., which will reduce the service life of the materials and reduce the strength of the materials. The reaction dynamics of the materials with gases in these atmospheres are deeply affected by temperature. Studying the microstructure of the surface materials in these atmospheres and their evolution laws with time and temperature is an important part of material research.

[0003] In the in-situ atmosphere reaction grazing incidence experiment, the reaction gas will react with the material to obtain a reaction product. The existing in-situ atmosphere reaction grazing incidence experiment equipment cannot achieve the isolation between the reaction product and the experimental operator, resulting in the reaction product being inhaled by the experimental operator and causing the risk of poisoning. Summary of the invention

[0004] The object of the present invention is to provide an in-situ atmosphere reaction grazing incidence experimental device, which can achieve isolation between reaction products and experimental operators during the in-situ atmosphere reaction grazing incidence experiment to avoid the risk of poisoning.

[0005] Based on the above purpose, the present invention provides an in-situ atmosphere reaction grazing incidence experimental device, comprising a position adjustment device, a temperature changing device and a gas reaction device, wherein the temperature changing device is arranged on the position adjustment device, and the gas reaction device is fixed on the temperature changing device, and the position adjustment device is used to adjust the positions of the temperature changing device and the gas reaction device; the temperature changing device comprises a first shell, a cold and hot element and a cover body, the first shell has a first inner cavity, the gas reaction device comprises a second shell, a covering element and an exit window, the second shell defines a second inner cavity having an incident opening and an exit opening, the covering element covers the incident opening, a light inlet channel for X-rays to pass through is provided on the covering element, the exit window covers the exit opening and is arranged to allow X-rays to pass through; the cold and hot element and the cover body are both located in the second inner cavity, the cover body is fixedly connected to the second shell body and covers the cold and hot element, the cover body is used to support a sample, and the cold and hot element keeps in contact with the cover body to change the temperature of the cover body and the sample; the second shell body is provided with a vent hole for introducing a reaction gas into the second inner cavity.

[0006] Furthermore, the temperature changing device comprises an elastic support member, one end of which is connected to the first shell, and the other end of which is connected to the hot and cold element, so as to provide the hot and cold element with an elastic force to keep the hot and cold element in contact with the cover body.

[0007] Furthermore, a first sealing film is provided between the exit window and the exit opening, and the first sealing film is used for sealing the exit opening.

[0008] Further, the covering element includes a first covering plate, a second sealing film and a second covering plate which are sequentially arranged along the X-ray transmission direction, the first covering plate is provided with a first light inlet hole, the second covering plate is provided with a second light inlet hole, the first light inlet hole and the second light inlet hole are aligned along the X-ray transmission direction and form a light inlet channel, the first covering plate is fixed to the second shell and covers the incident opening, the second covering plate is fixed to the first covering plate, and the second sealing film is sandwiched between the first covering plate and the second covering plate and is used to seal the second light inlet hole.

[0009] Furthermore, a heating device is integrated in the hot and cold element, a cable interface is provided on the first shell, and the heating device is electrically connected to the cable interface; a refrigeration pipe is built into the hot and cold element, an air inlet and an air outlet are provided on the first shell, and the air inlet and the air outlet are both connected to the refrigeration pipe to introduce low-temperature nitrogen into the refrigeration pipe.

[0010] Furthermore, it also includes a shading device, which includes a bracket and a shading plate. The bracket is fixed on the position adjustment device, and the shading plate is fixed on the bracket. The shading plate is provided with a light hole for X-rays to pass through.

[0011] Furthermore, the position adjustment device includes a first translation stage, a second translation stage and a third translation stage, the second translation stage is arranged on the first translation stage, the third translation stage is arranged on the second translation stage, the temperature variable device is arranged on the third translation stage, and the bracket is arranged on the first translation stage; the first translation stage is used to realize X, Y and Z direction movement, the second translation stage is used to rotate the sample around the X direction and around the Y direction, and the third translation stage is used to move the sample along the X direction.

[0012] Furthermore, the sample is fixed on a sample stage, and the sample stage is fixed on the cover; there are multiple samples, and they are arranged in sequence along the X direction.

[0013] Furthermore, it also includes a filtering device, which is fixedly connected to the second shell and covers the vent hole. The filtering device has a filtering chamber, which is connected to the vent hole. A vacuum valve is provided on the filtering device.

[0014] Furthermore, a beam blocker and a detector are sequentially arranged downstream of the gas reaction device.

[0015] In the in-situ atmosphere reaction grazing incidence experimental device of the present invention, the second inner cavity of the gas reaction device can be isolated from the outside world, so the reaction product will not leak from the second inner cavity to the outside world, avoiding poisoning caused by inhalation of the reaction product by the experimental operator; the cover body covers the hot and cold elements and isolates them from the rest of the second inner cavity, avoiding corrosion of the hot and cold elements by the reaction gas and reaction products; the filtering device can filter the reaction gas and reaction products, further avoiding leakage of toxic substances. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A cross-sectional view of a YZ plane of an in-situ atmosphere reaction grazing incidence experimental device according to an embodiment of the present invention;

[0017] Figure 2 It is an exploded schematic diagram of a gas reaction device and a temperature changing device of an in-situ atmosphere reaction grazing incidence experimental device according to an embodiment of the present invention;

[0018] Figure 3 It is a structural schematic diagram of a second shell of a gas reaction device of an in-situ atmosphere reaction grazing incidence experimental device according to an embodiment of the present invention;

[0019] Figure 4 It is a cross-sectional view of the XZ plane of the in-situ atmosphere reaction grazing incidence experimental device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0021] like Figure 1 , Figure 2 and Figure 3As shown, an embodiment of the present invention provides an in-situ atmosphere reaction grazing incidence experimental device, comprising a position adjustment device 100, a temperature change device 200 and a gas reaction device 300, wherein the temperature change device 200 is arranged on the position adjustment device 100, and the gas reaction device 300 is fixed on the temperature change device 200, and the position adjustment device 100 is used to move the temperature change device 200 and the gas reaction device 300 to adjust their positions; the temperature change device 200 comprises a first shell 210, a cold and hot element 220 and a cover body 230, the first shell 210 has a first inner cavity 211, the gas reaction device 300 comprises a second shell 310, a covering element 320 and an exit window 330, the second shell 310 defines a second inner cavity 311 having an incident opening 312 and an exit opening 313, the covering element 320 covers the incident opening 312, and a light inlet channel for X-rays to enter is provided on the covering element 320; the exit window 330 covers the exit opening 313, and the light inlet channel 330 is provided on the covering element 320; the exit window 330 covers the exit opening 314, and the light inlet channel 330 is provided on the covering element 320; the exit window 330 covers the exit opening 315, and the light inlet channel 330 is provided on the covering element 320; the exit window 330 covers the exit opening 316, and the light inlet channel 330 is provided on the covering element 320; the light inlet channel 330 covers the exit opening 317, and the light inlet channel 330 covers the exit opening 318. The opening 313 can isolate the second inner cavity 311 from the outside on the one hand, and can also allow the X-rays to pass through and be emitted from the exit window 330 on the other hand; the hot and cold element 220 and the cover body 230 are both located in the second inner cavity 311, and the cover body 230 is fixedly connected to the second shell 310 and covers the hot and cold element 220, so as to isolate the hot and cold element 220 from the rest of the second inner cavity 311, and prevent the reaction gas and reaction products from contacting and corroding the hot and cold element 230; the hot and cold element 220 keeps in contact with the cover body 230, and is used to radiate cold or heat outward to change the temperature of the cover body 230; the cover body 230 is also used to support the sample 400, so as to transfer cold or heat to the sample 400 and change the temperature of the sample 400; the second shell 310 is provided with a vent hole 314, which is used to evacuate the second inner cavity 311 and introduce reaction gas into the second inner cavity 311, so as to carry out an in-situ atmosphere reaction grazing incidence experiment. During the experiment, the synchrotron radiation X-rays are transmitted along the Y direction. The position of the gas reaction device 300 is adjusted by the adjusting device 100 so that the light inlet channel of the cover element 320 is located on the optical path of the X-rays, so that the X-rays can enter the second inner cavity 311 from the light inlet channel and the incident opening 312, and irradiate the sample 400, and then be reflected by the sample 400, and the reflected light is emitted from the exit window 330. A detector 500 for receiving the reflected light can be arranged downstream of the gas reaction device 300, so as to collect the diffraction or scattering signal of the sample 400 to obtain the sample 400. Surface microstructure information; during the experiment, different reaction gases, such as hydrogen, water vapor, oxygen, chlorine, methane, carbon monoxide, etc., can be introduced into the second inner cavity 311 to carry out grazing incidence experiments under different reaction gases. The temperature of the sample 400 can be adjusted by the hot and cold element 220 to achieve grazing incidence experiments at different temperatures. For example, the hot and cold element 220 can make the temperature of the sample 400 vary between -60°C and 200°C. In this way, the grazing incidence experimental device of the embodiment of the present invention can achieve grazing incidence experiments between -60°C and 200°C.Since the second inner cavity 311 is isolated from the outside, the reaction product will not leak from the second inner cavity 311 to the outside, thereby preventing the experimental operator from inhaling the reaction product and being poisoned.

[0022] In some embodiments, the exit window 330 may be formed in an arc shape so that the detector 500 can collect diffraction / scattering signals within the exit angle range of 0 to 90 degrees.

[0023] In some embodiments, the temperature changing device 200 may further include an elastic support member 240, one end of which is connected to the first shell 210 and the other end is connected to the cold and hot element 220, so as to provide an elastic support force to the cold and hot element 220, and the elastic support force keeps the cold and hot element 220 in contact with the cover 230. The first inner cavity 211 may have a top opening, and the second shell 310 may cover the top opening. The second shell 310 is provided with a connecting port 315, and the connecting port 315 is used to connect the first inner cavity 211 with the second inner cavity 311. The elastic support member 240 is located in the first inner cavity 211, and one end of the elastic support member 240 enters the second inner cavity 311 through the connecting port 315 and is connected to the cold and hot element 220, and the cover 230 covers the connecting port 315, so that the cold and hot element 220 is isolated from the rest of the second inner cavity 311.

[0024] In some embodiments, a first sealing film 340 may be provided between the exit window 330 and the exit opening 313 to seal the exit opening 313 to prevent leakage of the reaction gas and reaction products in the second inner cavity 311; the first sealing film 340 is a transparent film, which can allow X-rays to pass through on one hand, and on the other hand, can facilitate experimental operators to observe the sample 400 in the second inner cavity 311. Exemplarily, the first sealing film 340 may be a polyimide film.

[0025] In some embodiments, the covering element 320 may include a first covering plate 321, a second sealing film 322, and a second covering plate 323 sequentially arranged along the X-ray transmission direction, the first covering plate 321 is provided with a first light inlet hole 3211, the second covering plate 323 is provided with a second light inlet hole 3231, the first light inlet hole 3211 and the second light inlet hole 3231 are aligned along the X-ray transmission direction and form a light inlet channel, the first covering plate 321 is fixed to the second housing 310 and covers the incident opening 312, the second covering plate 323 is fixed to the first covering plate 311, the second sealing film 322 is sandwiched between the first covering plate 321 and the second covering plate 323, and is used to seal the first light inlet hole 3211 and the second light inlet hole 3231. The second sealing film 322 may be a polyimide film.

[0026] In some embodiments, a temperature sensor (not shown) is provided in the second inner cavity 311, and the temperature sensor is used to detect the temperature of the cover body 230 or the sample 400. A cable interface 316 is provided on the second housing 310, and the temperature sensor is electrically connected to an external power source or controller through the cable interface 316, thereby realizing power supply and signal transmission. Exemplarily, the temperature sensor can be a thermocouple, which is provided on the surface of the cover body 230 or the sample 400.

[0027] In some embodiments, a vacuum hole 212 may be provided on the first shell 210 , and the first inner cavity 211 may be evacuated through the vacuum hole 212 , so that the first inner cavity 211 forms a vacuum environment.

[0028] In some embodiments, the cold and hot element 220 is a silver or copper cooling body and heating body, which is integrated with a heating device. The cold and hot element 220 can be heated by heating with the heating device; the first shell 210 can be provided with a cable interface 213, and the heating device is connected to an external controller through the cable interface 213, so that the operation of the heating device can be controlled by the controller to adjust the temperature of the cold and hot element 220. The cold and hot element 220 is also built with a refrigeration pipeline, and the first shell 210 is provided with an air inlet 214 and an air outlet 215, and the air inlet 214 and the air outlet 215 are both connected to the refrigeration pipeline. Low-temperature nitrogen can be introduced into the refrigeration pipeline through the air inlet 214, and it is discharged from the air outlet 215 after passing through the refrigeration pipeline to form a circulation path. The low-temperature nitrogen can cool the cold and hot element 220, thereby achieving refrigeration. The elastic support 240 can be made of heat-resistant material to prevent heat or cold from being transmitted from the elastic support 240 to the first shell 210 and affecting the heating or cooling effect. Exemplarily, the hot and cold element 220 can change the temperature of the cover 230 and the sample 400 between -60 and 200°C.

[0029] In some embodiments, the in-situ atmosphere reaction grazing incidence experimental device further includes a shading device, which includes a bracket 610 and a shading plate 620. The bracket 610 is fixed on the position adjustment device 100, and the shading plate 620 is fixed on the bracket 610. The shading plate 620 is provided with a light hole 621 for X-rays to pass through. The light hole 621 is aligned with the light inlet channel of the gas reaction device 300 and the sample 400 along the X-ray transmission direction, so that the X-rays can be irradiated on the sample 400. The shading device can limit the X-ray air stray rays from irradiating the detector, reduce the background signal of diffraction / scattering, and improve the data quality.

[0030] In some embodiments, the sample 400 may be fixed on a sample holder, and the sample holder is fixed on the hot and cold element 220 .

[0031] In some embodiments, the position adjustment device 100 includes a first translation stage 110, a second translation stage 120, and a third translation stage 130. The second translation stage 120 is disposed on the first translation stage 110, the third translation stage 130 is disposed on the second translation stage 120, the temperature changing device 200 is disposed on the third translation stage 130, the bracket 610 is fixed on the first translation stage 110, the first translation stage 110 is used to move the device thereon in the X, Y, and Z directions, the second translation stage 120 is used to rotate the device thereon around the Y direction and around the X direction, and the third translation stage 130 is used to move the device thereon in the X direction. Therefore, the X, Y, and Z directions of the sample 400 can be adjusted by the first translation stage 110, the sample 400 can be rotated around the Y and X directions by the second translation stage 120 to tilt within the range of ±5°, and the X direction position of the sample 400 can be adjusted by the third translation stage 130.

[0032] In some embodiments, there may be multiple samples 400, and they are fixed on the sample holder at intervals in the X direction. By moving each sample 400 in the X direction through the third displacement stage 130, any sample 400 can be moved to the optical path of the X-ray, thereby realizing the X-ray grazing incidence experiment of different samples 400 and improving the experimental efficiency. When there are multiple samples 400, there may be multiple first light inlets 3211, and they are aligned one by one with each sample 400. The second light inlet 3231 is in the shape of a long strip and can cover all the first light inlets 3211, that is, any light inlet 3211 is aligned with the second light inlet 323 in the Y direction. In this way, when any sample 400 moves to the optical path, the X-rays can enter the second light inlet 323 through the first light inlet 3211, and then enter the second inner cavity 311 through the second light inlet 323. The light hole 621 may also be configured as a long strip, and its size in the X direction is close to that of the first light inlet hole 3211, so that X-rays can enter the second inner cavity 311 through a first light inlet hole 3211, and the light shielding plate 620 blocks X-ray air stray rays from entering other first light inlet holes 3211. The size of the light hole 621 also needs to be large enough so that X-rays can be irradiated on the sample 400 even after the sample 400 is rotated and moved.

[0033] In some embodiments, a beam blocker (not shown in the figure) may also be provided between the gas reaction device 200 and the detector 500. The beam blocker is located on the optical path of the X-ray. A photodiode is built into the center of the beam blocker to observe the central beam flux on the light output side and guide the light cutting operation of the grazing incidence experimental test.

[0034] like Figure 4As shown, in some embodiments, the in-situ atmosphere reaction grazing incidence experimental device further includes a filter device 700, which is fixedly connected to the second shell 310 and covers the vent hole 314. The filter device 700 has a filter chamber, which is connected to the vent hole 314 and is used to filter the reaction gas and reaction products in the second inner cavity 311 to prevent toxic substances from leaking to the outside. The filter device 700 and the second shell 310 can be fixed to the second shell 310 by screws or flange blocks.

[0035] In some embodiments, a vacuum valve 800 may be further provided on the filter device 700, and the connection between the filter device 700 and the outside world may be controlled by the vacuum valve 800. After the filter device 700 has fully filtered the reaction gas and the reaction product, the vacuum valve 800 may be opened to prevent toxic substances from leaking to the outside world.

[0036] In some embodiments, there may be two vent holes 314 , which may be located on two opposite side walls of the second shell 310 along the X direction; accordingly, there are also two filtering devices 700 , which respectively cover the two vent holes 314 to filter the reaction gas and reaction material flowing out of the two vent holes 314 .

[0037] The method of using the in-situ atmosphere reaction grazing incidence experimental device of the embodiment of the present invention is as follows:

[0038] After placing the sample 400 in the second inner cavity 311, the first inner cavity 211 and the second inner cavity 311 are evacuated, and then a preset reaction gas is introduced into the second inner cavity 311, and the sample 400 is adjusted to a preset temperature by the cold and hot element 220, and then X-rays are irradiated on the sample 400, and the diffraction or scattering signal is received by the detector 500 to perform a grazing incidence experiment under the preset reaction gas and preset temperature. During the experiment, the sample 400 can be rotated around the X direction and / or the Y direction by the second translation stage 120 to collect diffraction signals at different angles. or scattered signals; when there are multiple samples 400, each sample 400 can be moved along the X direction through the third translation stage 130, and one of the samples 400 is first moved to the optical path of the X-ray, and then a grazing incidence experiment is performed on the sample 400, and after completion, another sample 400 is moved to the optical path to perform a grazing incidence experiment on the sample 400, and so on, until the grazing incidence experiments of all samples 400 are completed; thereby, grazing incidence experiments of multiple samples 400 under preset reaction gases and preset temperatures can be realized simultaneously, and the capability of high-throughput grazing incidence experiments is possessed.

[0039] In the in-situ atmosphere reaction grazing incidence experimental device of the embodiment of the present invention, the second inner cavity 311 of the gas reaction device 300 can be isolated from the outside world, so the reaction product will not leak from the second inner cavity 311 to the outside world, avoiding the experimental operators from inhaling the reaction products and getting poisoned; the cover body 230 covers the hot and cold element 220 and isolates it from the rest of the second inner cavity 311, avoiding the reaction gas and reaction products from corroding the hot and cold element 220; the filter device 700 can filter the reaction gas and reaction products, further avoiding the leakage of toxic substances.

[0040] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. An in-situ atmosphere reaction grazing incidence experimental device, characterized in that: The invention comprises a position regulating device, a temperature changing device and a gas reaction device, wherein the temperature changing device is arranged on the position regulating device, the gas reaction device is fixed on the temperature changing device, and the position regulating device is used to adjust the positions of the temperature changing device and the gas reaction device; the temperature changing device comprises a first shell, a cold and hot element and a cover body, the first shell has a first inner cavity, the gas reaction device comprises a second shell, a covering element and an exit window, the second shell defines a second inner cavity having an incident opening and an exit opening, the covering element covers the incident opening, a light inlet channel for X-rays to pass through is arranged on the covering element, the exit window covers the exit opening and is arranged to allow X-rays to pass through; the cold and hot element and the cover body are both located in the second inner cavity, the cover body is fixedly connected to the second shell body and covers the cold and hot element, the cover body is used to support a sample, the cold and hot element keeps in contact with the cover body to change the temperature of the cover body and the sample; the second shell body is provided with a vent hole for introducing a reaction gas into the second inner cavity.

2. The in-situ atmosphere reaction grazing incidence experimental device according to claim 1, characterized in that: The temperature changing device comprises an elastic support member, one end of which is connected to the first shell, and the other end of which is connected to the hot and cold element, so as to provide the hot and cold element with an elastic force to keep the hot and cold element in contact with the cover body.

3. The in-situ atmosphere reaction grazing incidence experimental device according to claim 1, characterized in that: A first sealing film is provided between the exit window and the exit opening, and the first sealing film is used to seal the exit opening.

4. The in-situ atmosphere reaction grazing incidence experimental device according to claim 1, characterized in that: The covering element includes a first covering plate, a second sealing film and a second covering plate which are sequentially arranged along the X-ray transmission direction, the first covering plate is provided with a first light inlet hole, the second covering plate is provided with a second light inlet hole, the first light inlet hole and the second light inlet hole are aligned along the X-ray transmission direction and form a light inlet channel, the first covering plate is fixed to the second shell and covers the incident opening, the second covering plate is fixed to the first covering plate, and the second sealing film is sandwiched between the first covering plate and the second covering plate and is used to seal the second light inlet hole.

5. The in-situ atmosphere reaction grazing incidence experimental device according to claim 1, characterized in that: A heating device is integrated in the hot and cold element, a cable interface is provided on the first shell, and the heating device is electrically connected to the cable interface; a refrigeration pipeline is built into the hot and cold element, an air inlet and an air outlet are provided on the first shell, and the air inlet and the air outlet are both connected to the refrigeration pipeline to introduce low-temperature nitrogen into the refrigeration pipeline.

6. The in-situ atmosphere reaction grazing incidence experimental device according to claim 1, characterized in that: It also includes a shading device, which includes a bracket and a shading plate. The bracket is fixed on the position adjustment device, and the shading plate is fixed on the bracket. The shading plate is provided with a light hole for X-rays to pass through.

7. The in-situ atmosphere reaction grazing incidence experimental device according to claim 6, characterized in that: The position adjustment device includes a first translation stage, a second translation stage and a third translation stage, wherein the second translation stage is arranged on the first translation stage, the third translation stage is arranged on the second translation stage, the temperature variable device is arranged on the third translation stage, and the bracket is arranged on the first translation stage; the first translation stage is used to realize movement in the X, Y and Z directions, the second translation stage is used to rotate the sample around the X direction and around the Y direction, and the third translation stage is used to move the sample along the X direction.

8. The in-situ atmosphere reaction grazing incidence experimental device according to claim 1, characterized in that: The sample is fixed on a sample stage, and the sample stage is fixed on the cover body; there are multiple samples, and they are arranged in sequence along the X direction.

9. The in-situ atmosphere reaction grazing incidence experimental device according to claim 1, characterized in that: It also includes a filter device, which is fixedly connected to the second shell and covers the vent hole. The filter device has a filter chamber, which is connected to the vent hole. A vacuum valve is provided on the filter device.

10. The in-situ atmosphere reaction grazing incidence experimental device according to claim 1, characterized in that: A beam blocker and a detector are arranged in sequence downstream of the gas reaction device.

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