Plasmonic raman in-situ cell

Abstract

This invention discloses an in-situ plasma Raman cell, comprising a main body assembly, a positive electrode inner rod, a negative electrode ring, a first quartz outer cover, a second quartz outer cover, and a cover assembly. An annular sample cell is formed at the top of the main body assembly. The negative electrode ring is coaxially fitted tightly against the inner wall of the annular sample cell. The positive electrode inner rod is vertically positioned at the center of the negative electrode ring. The first and second quartz outer covers are axially fitted onto the outer walls of the positive electrode inner rod and the inner walls of the negative electrode ring, respectively. The cover assembly is detachably sealed to the top of the sample cell, forming an airtight structure. This axially fitted structure allows the annular plasma arc generated between the positive electrode inner rod and the negative electrode ring to more comprehensively cover the reaction system, ensuring a stable reaction atmosphere. After energization, a uniform electric field is generated within the annular sample cell, avoiding localized concentration or uneven distribution of plasma caused by asymmetric electrodes, ensuring sufficient and uniform contact between the sample and the plasma, and guaranteeing the accuracy and repeatability of experimental results.

Description

Technical Field

[0001] This utility model relates to the technical field of spectrometer accessories and instrument analysis, specifically to a plasma Raman in-situ cell. Background Technology

[0002] In the field of spectroscopic analysis, inductively coupled plasma Raman spectroscopy (ICP-Raman) is widely used in materials science, catalysis, environmental monitoring, and other research areas because it can capture the changes in molecular structure of substances under the influence of plasma in real time. The in-situ ICP-Raman cell, as a core component of this technology, directly determines the accuracy, stability, and reliability of the experimental data.

[0003] However, existing in-situ plasma Raman cells have many problems that urgently need to be solved:

[0004] Poor sealing performance: Most in-situ cells use a simple cover snap-fit ​​structure, which makes it difficult to achieve gas sealing. This leads to easy leakage of reaction gas during the experiment, which not only affects the stable generation of plasma, but may also introduce external impurities to interfere with Raman signal detection. Especially in experiments involving toxic, flammable or rare gases, both safety and experimental accuracy cannot be guaranteed.

[0005] Low gas control precision: The design of the gas inlet and outlet channels in the existing in-situ cells is unreasonable. Most of them are non-parallel openings or single channel structures, which leads to uneven distribution of reactant gases in the cell and makes it impossible to form a stable gas flow environment. This affects the uniform interaction between plasma and sample, resulting in poor experimental repeatability.

[0006] Insufficient discharge stability: The structural design of the positive and negative electrodes lacks reasonable insulation and protection measures. On the one hand, leakage between electrodes is prone to occur, leading to unstable plasma discharge. On the other hand, the electrodes are directly exposed to the reaction environment, making them susceptible to corrosion or contamination, which shortens their service life. Meanwhile, impurities on the electrode surface can also interfere with the Raman spectral signal.

[0007] Limited observation and detection: Some in-situ cells have covers made of non-transparent materials, or the relative positions of the transparent cover, electrodes, and samples are not properly designed, which makes it impossible for the Raman laser to be accurately focused on the plasma interaction area and to observe the reaction state in the cell in real time. In addition, unreasonable electrode structure design may also block the Raman signal acquisition path, reducing signal strength and detection sensitivity.

[0008] Disassembly and maintenance are inconvenient: The existing in-situ pool covers are mostly fixed by bolts or clips, which makes disassembly and assembly cumbersome. Repeated disassembly and assembly can easily lead to wear of the seals, further reducing the sealing performance. At the same time, the assembly structure of the electrodes and insulating components is complex, and maintenance requires complete disassembly, which is difficult to operate.

[0009] These problems severely restrict the application and expansion of plasma Raman spectroscopy technology, and there is an urgent need for a plasma Raman in-situ cell that is reliably sealed, has precise gas control, stable discharge, and is easy to observe and maintain. Utility Model Content

[0010] Therefore, this invention provides an in-situ plasma Raman cell to solve the above-mentioned problems in the prior art.

[0011] To achieve the above objectives, this utility model provides the following technical solution:

[0012] According to a first aspect of the present invention, a plasma Raman in-situ cell includes a body assembly, a positive electrode inner rod, a negative electrode ring, a first quartz outer cover, a second quartz outer cover, and a cover assembly; the top of the body assembly has an annular sample cell, the negative electrode ring is coaxially sleeved on the inner wall of the annular sample cell and tightly fitted to the inner wall, the positive electrode inner rod is vertically disposed at the center of the negative electrode ring, the first quartz outer cover is axially sleeved on the outer wall of the positive electrode inner rod, the second quartz outer cover is axially sleeved on the inner wall of the negative electrode ring, and the cover assembly is detachably sealed to the top opening of the annular sample cell, and the cover assembly and the top of the annular sample cell form an airtight structure.

[0013] Furthermore, the main body assembly includes a base, an air outlet, an air inlet, a positive terminal, and a negative terminal; the annular sample cell is disposed above the base, and the base has an annular receiving groove near the outer periphery of the annular sample cell, the bottom of the cover assembly is embedded in the annular receiving groove and sealed to the inner wall of the receiving groove; the base has an air outlet channel and an air inlet channel inside, the air outlet is located on the side wall of the base and communicates with the annular sample cell through the air outlet channel, the air inlet is located on the side wall of the base and communicates with the annular sample cell through the air inlet channel, and the openings of the air outlet channel and the air inlet channel in the annular sample cell are arranged parallel to each other; the positive terminal and the negative terminal are respectively embedded on both sides of the base, the positive terminal passes through the base and is electrically connected to the bottom of the positive inner rod, and the top of the negative terminal passes through the base and is electrically connected to the bottom of the negative ring.

[0014] Furthermore, the cover assembly includes a cap pressing sheet, a cap, and a rubber ring; the rubber ring is annular, with one side of the rubber ring tightly fitted to the bottom edge of the cap and the other side tightly fitted to the top opening face of the annular sample cell; sliding guide structures are respectively provided on the bases on both sides of the annular sample cell, and the two cap pressing sheets are slidably disposed on the sliding guide structures, with the opposite sides of the two cap pressing sheets pressed against the top two sides of the cap, so that the cap seals the top opening of the annular sample cell through the rubber ring.

[0015] Furthermore, the sliding guide structure is a threaded hole opened on the base, and the pool cap pressure plate is provided with an elongated sliding hole extending along the sliding direction. The pool cap pressure plate is threaded to the threaded hole of the base after passing through the sliding hole with a fastening screw. Tightening the fastening screw can fix the pool cap pressure plate on the base.

[0016] Furthermore, the top of the first quartz outer cover is integrally formed into a hemispherical structure, the top of the hemispherical structure is higher than the top of the inner rod of the positive electrode, and there is a gap of 0.1~0.5mm between the inner wall of the first quartz outer cover and the outer wall of the inner rod of the positive electrode; the top of the second quartz outer cover is flush with the top opening of the annular sample cell, and the inner wall of the second quartz outer cover is flush with the inner wall of the annular sample cell.

[0017] Furthermore, the pool cap is a one-piece molded structure made of transparent quartz material, and the rubber ring is a one-piece molded structure made of fluororubber material.

[0018] Furthermore, the inner rod of the positive electrode is a cylindrical structure with a central through hole.

[0019] This invention has the following advantages: The negative electrode ring is tightly fitted to the inner wall of the annular sample cell, and the second quartz outer cover is axially fitted onto the inner wall of the negative electrode ring, forming a radial sealing barrier; the cover assembly is detachably sealed to the top opening of the annular sample cell, forming a complete gas-tight structure together with the top of the cell, effectively blocking the entry of external air and impurities, avoiding gas leakage or external interference during the experiment, and is especially suitable for Raman detection scenarios requiring inert gas protection or a specific reactive gas atmosphere. The axial fitting structure of the first quartz outer cover and the inner rod of the positive electrode, and the second quartz outer cover and the negative electrode ring, allows the plasma annular arc generated between the inner rod of the positive electrode and the negative electrode ring to more comprehensively cover the reaction system, ensuring the stability of the reaction atmosphere during plasma generation, and laying the foundation for accurate in-situ Raman signal acquisition. The coaxial arrangement of the positive electrode inner rod and the negative electrode ring significantly improves plasma performance. The positive electrode inner rod is vertically positioned at the center of the negative electrode ring, forming a coaxially symmetrical electric field distribution. After energization, a uniform electric field intensity can be generated within the annular sample cell, avoiding the problems of localized plasma concentration or uneven distribution caused by traditional asymmetric electrodes. This ensures sufficient and uniform contact between the sample and the plasma, improving reaction consistency and the representativeness of the Raman signal. Quartz outer covers one and two respectively house the positive electrode inner rod and the negative electrode ring, achieving physical isolation between the electrode and the sample and reactant gases, preventing electrode material dissolution, oxidation, and other contamination of the sample, effectively protecting the electrode. This also does not affect plasma penetration and action, extending electrode lifespan while ensuring the accuracy and repeatability of experimental results. Attached Figure Description

[0020] To more clearly illustrate the embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0021] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the implementation conditions of this utility model. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportional relationships, or adjustments to the size, without affecting the effects and purposes that this utility model can produce, should still fall within the scope of the technical content disclosed in this utility model.

[0022] Figure 1 A three-dimensional plasma Raman in-situ cell provided for some embodiments of this utility model Figure 1 .

[0023] Figure 2 This is a schematic diagram of the main body assembly of a plasma Raman in-situ cell provided for some embodiments of the present invention.

[0024] Figure 3 A top view of a plasma Raman in-situ cell provided for some embodiments of this utility model.

[0025] Figure 4 A cross-sectional view of a plasma Raman in-situ cell provided for some embodiments of this utility model.

[0026] Figure 5 An exploded view of a plasma Raman in-situ cell provided for some embodiments of this utility model.

[0027] In the diagram: 1. Air outlet; 2. Air inlet; 3. Pool cap pressure plate; 4. Pool cap; 5. Positive terminal; 6. Negative terminal; 7. Positive inner rod; 8. Negative ring; 9. Quartz outer cover one; 10. Quartz outer cover two; 11. Rubber ring; 12. Annular receiving groove. Detailed Implementation

[0028] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0029] An in-situ plasma cell is a reaction chamber that provides both reaction and characterization environments, encompassing plasma catalytic reactions and emission spectroscopy testing. Under a plasma field, gas-solid catalytic reactions can occur under milder conditions, exhibiting high selectivity for value-added product formation and extremely fast start-up times. Operating at lower temperatures also reduces coke formation and catalyst poisoning, thereby extending catalyst lifespan. However, our understanding of specific plasma-catalyst interactions and the underlying processes is still very limited. Adding in-situ characterization capabilities to the reaction chamber allows for better observation of the fundamental processes involved in the reaction.

[0030] In-situ Raman spectroscopy relies on the scattering of incident light by molecules to obtain relevant information about a sample. When incident light interacts with a substance, a small subset of photons, with frequencies different from the incident light, undergo inelastic scattering, known as Raman scattering. These photons provide information about intramolecular and intermolecular vibrations, allowing for the study of the substance's composition or structural properties. In-situ Raman spectroscopy is characterized by its speed, sensitivity, non-destructive nature, small sample requirements, ability to identify characteristic vibrations, and wide testing range, making it highly valuable in catalyst characterization, biological sample research, and chemical reaction monitoring. Atomic emission spectrometry (AES) is a method for qualitative and quantitative elemental analysis based on the characteristic electromagnetic radiation emitted by atoms or ions of various chemical elements when they return to their ground state after thermal or electrical excitation. It is widely used in elemental analysis due to its high sensitivity, good selectivity, and fast analysis speed.

[0031] Characterization tests conducted in actual chemical reaction environments can reduce interference from human sampling and improve the accuracy of test results through real-time monitoring.

[0032] Example 1

[0033] like Figures 1 to 5 As shown, a plasma Raman in-situ cell in the first aspect embodiment of the present invention mainly consists of the following parts: a body assembly serving as the main support and fluid channel; a positive electrode inner rod 7 and a negative electrode ring 8 serving as the core discharge electrodes; a quartz outer cover 9 and a quartz outer cover 10 for protecting the electrodes and allowing plasma excitation and optical signal transmission; and a cover assembly for sealing the top of the reaction cell.

[0034] Specifically, an annular sample cell is machined on the top of the main body assembly, which is used to contain the sample to be tested and the reaction gas. The negative electrode ring 8 is coaxially mounted in the cell with its outer wall tightly fitted to the inner wall of the annular sample cell. The positive electrode inner rod 7 is vertically and precisely fixed at the geometric center of the negative electrode ring 8. This coaxial arrangement ensures that when a voltage is applied between the positive electrode inner rod 7 and the negative electrode ring 8, an axisymmetric uniform electric field can be formed within the annular space of the annular sample cell, thereby exciting a stable and uniform annular plasma, which is crucial for obtaining a Raman signal with good repeatability.

[0035] In order to protect the electrodes from corrosion by the reaction environment, prevent the electrode materials from contaminating the sample or interfering with the Raman signal, and at the same time not hinder the establishment of the electric field and the generation of plasma, a quartz outer cover 9 is fitted around the outer periphery of the inner rod 7 of the positive electrode, and a quartz outer cover 10 is fitted around the inner periphery of the ring 8 of the negative electrode.

[0036] To maintain the necessary atmosphere for the reaction and prevent the leakage of harmful gases, the top opening of the annular sample cell is removably sealed by a cover assembly. This cover assembly fits precisely with the top of the cell, forming a reliable gas-tight structure that ensures the safety of the experimental process and the purity of the reaction atmosphere.

[0037] The base of the main body assembly integrates gas passages. Inlet 2 and outlet 1 are connected to the annular sample cell via independently machined inlet and outlet channels within the base, respectively. A key design feature is that the openings of the inlet and outlet channels within the annular sample cell are arranged in parallel. This parallel airflow design helps to create a stable and uniform laminar or piston flow within the annular cavity, allowing the reactant gas to pass fully and consistently through the plasma interaction region, avoiding eddies or dead zones. This ensures that samples in all regions experience the same reaction conditions, improving experimental uniformity and data reliability.

[0038] Electrical connections are achieved through positive terminal 5 and negative terminal 6. These are embedded on both sides of the base. Positive terminal 5 passes through the base and connects to the bottom of the positive inner rod 7, while the top of negative terminal 6 passes through the base and connects to the bottom of the negative ring 8. This arrangement allows for easy access to an external power source while maintaining the compactness of the pool structure.

[0039] The cover assembly specifically includes a cell cap 4, a rubber ring 11, and a cell cap pressing plate 3. The cell cap 4 serves as both an observation window and a sealing cover, while the rubber ring 11 acts as a sealing element, positioned between the cell cap 4 and the end face of the top opening of the annular sample cell. Sliding guide structures are provided on the base on both sides of the annular sample cell, and the two cell cap pressing plates 3 are slidably mounted on these guide structures. By sliding the two cell cap pressing plates 3, their opposite sides press against the top two sides of the cell cap 4, thus tightly pressing the cell cap 4 against the top of the annular sample cell via the rubber ring 11, achieving an effective seal. An annular receiving groove 12, formed around the outer periphery of the annular sample cell on the base, is used to receive and position the bottom edge of the cover assembly, further enhancing the stability of the seal and the ease of assembly.

[0040] The technical effects achieved by the above embodiments are as follows: By combining the coaxial electrode design with parallel airflow channels, an ideal plasma reaction environment with a uniform electric field and stable airflow is created. The quartz outer cover effectively isolates and protects the electrodes, extending the equipment lifespan and ensuring signal purity. The detachable cover assembly, combined with a precise sealing structure, ensures airtightness while facilitating equipment maintenance and sample replacement. The overall structure is optimized for the needs of in-situ plasma Raman detection, significantly improving the accuracy, stability, and repeatability of the test.

[0041] Example 2

[0042] like Figures 1 to 5 As shown, an in-situ plasma Raman cell includes all the features of Example 1. In addition, a preferred implementation of the sliding guide structure is as follows: a threaded hole is formed in the base, and an elongated sliding hole extending along the sliding direction (i.e., the pressing / releasing direction) is machined on the cell cap pressure plate 3. During assembly, a fastening screw is passed through this sliding hole and screwed into the threaded hole of the base. When it is necessary to open the cell cap, the fastening screw can be loosened, and the cell cap pressure plate 3 can be slid open along the sliding hole direction, thereby releasing the pressure on the cell cap 4; when sealing is required, the cell cap pressure plate 3 is slid to the position pressing the cell cap 4, and then the fastening screw is tightened to fix it. This design enables quick and convenient tool-less or simple tool-free assembly and disassembly, greatly improving experimental efficiency and avoiding wear on the base threads caused by frequent screw tightening. It also facilitates the replacement of the cell cap.

[0043] The top of the quartz outer casing 9 is designed as a one-piece hemispherical structure. The top of this hemispherical structure is higher than the top of the positive electrode inner rod 7 it protects. This streamlined design has several advantages: First, it eliminates sharp corners at the top, reduces electric field concentration, and is beneficial to plasma stability; second, the smooth curved surface does not easily accumulate contaminants, making it easy to clean; finally, from an optical perspective, the hemispherical structure helps reduce aberrations and reflection losses during laser incident and Raman signal collection.

[0044] A precise gap, ranging from 0.1 mm to 0.5 mm, is maintained between the inner wall of the quartz outer casing 9 and the outer wall of the positive electrode inner rod 7. This gap needs to be small enough to minimize gas permeation and potential discharge inside the quartz tube, ensuring that plasma is primarily generated within the open space of the annular sample cell; at the same time, it needs to be large enough to facilitate assembly and prevent the quartz tube from breaking due to thermal expansion or manufacturing tolerances. This gap is a key parameter balancing insulation protection, plasma generation, and mechanical reliability.

[0045] The top of the quartz outer cover 210 is machined to be flush with the top opening of the annular sample cell, and its inner wall is also flush with the inner wall of the annular sample cell. This design makes the inner surface of the annular sample cell form a continuous, smooth cylindrical surface, eliminating steps and gaps that may cause airflow disturbance or sample residue, and ensuring the uniformity and cleanliness of the flow field in the reaction chamber.

[0046] The technical effects achieved by the above embodiments are as follows: the guide and clamping mechanism, which uses a long sliding hole and screws, simplifies the operation process and improves user experience and equipment maintenance efficiency. The hemispherical top of the first quartz housing optimizes the electric field distribution and optical performance, while the precisely controlled gap ensures the controllability of plasma generation and the reliability of electrode protection. The flush design of the second quartz housing further optimizes the internal environment of the reaction chamber, ensuring the acquisition of high-quality experimental data.

[0047] Example 3

[0048] like Figures 1 to 5 As shown, a plasma Raman in-situ cell includes all the contents of Example 2. The cell cap 4 is manufactured using a one-piece molding process with transparent quartz material. Transparent quartz was chosen because it has extremely high transmittance in the ultraviolet, visible, and even near-infrared bands, and possesses excellent heat resistance, chemical stability, and mechanical strength, enabling it to withstand the high temperatures and chemical corrosion in a plasma environment. The one-piece molding structure avoids potential sealing failures, contamination sources, or optical distortion problems caused by bonding or assembly, ensuring the purity and reliability of the observation window.

[0049] Rubber ring 11 is a one-piece molded structure made of fluororubber. Fluororubber is renowned for its excellent high-temperature resistance (capable of long-term operation above 200°C), superior chemical corrosion resistance (resistant to various oxidizing gases, solvents, etc.), and good elastic recovery. In this application, fluororubber is chosen as the sealing material to ensure that the in-situ cell maintains an effective seal for extended periods in a plasma environment filled with active gases and potentially increasing temperatures, preventing gas leakage and ensuring experimental safety and accuracy.

[0050] The inner rod 7 of the positive electrode is designed as a cylindrical structure with a central through hole. This hollow design can bring several potential advantages without significantly affecting its conductivity and mechanical strength: firstly, it can reduce the overall weight of the electrode; secondly, in specific applications, the through hole can serve as an auxiliary channel, such as for introducing trace amounts of reference gas, internal cooling media (such as circulating water or inert gas), or even for embedding micro-sensors (such as thermocouples), thereby expanding the functionality and application range of the in-situ cell.

[0051] The technical effects achieved by the above embodiments are as follows: the transparent quartz cell cap provides an ideal optical window for the excitation and collection of Raman signals, ensuring high signal fidelity. The fluororubber sealing ring provides material assurance for long-term stable sealing under harsh operating conditions. The hollow design of the positive electrode inner rod, while ensuring basic functions, gives the device greater design flexibility and functional expansion potential, enabling this in-situ plasma Raman cell to adapt to a wider range of more complex scientific research and industrial analysis needs.

[0052] Although the present invention has been described in detail above with general descriptions and specific embodiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

[0053] The terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity of description and are not intended to limit the scope of implementation of this utility model. Any changes or adjustments to their relative relationships, without substantially altering the technical content, shall also be considered within the scope of implementation of this utility model.

Claims

1. A plasma Raman in-situ cell, characterized in that, The device includes a main body assembly, a positive electrode inner rod, a negative electrode ring, a first quartz outer cover, a second quartz outer cover, and a cover assembly. The main body assembly has an annular sample cell at its top. The negative electrode ring is coaxially fitted onto the inner wall of the annular sample cell and is tightly fitted to the inner wall. The positive electrode inner rod is vertically positioned at the center of the negative electrode ring. The first quartz outer cover is axially fitted onto the outer wall of the positive electrode inner rod. The second quartz outer cover is axially fitted onto the inner wall of the negative electrode ring. The cover assembly is detachably sealed to the top opening of the annular sample cell, and the cover assembly and the top of the annular sample cell form an airtight structure.

2. The plasma Raman in-situ cell according to claim 1, characterized in that, The main body assembly includes a base, an air outlet, an air inlet, a positive terminal, and a negative terminal. The annular sample cell is positioned above the base. An annular receiving groove is formed on the outer periphery of the base near the annular sample cell. The bottom of the cover assembly is embedded in the annular receiving groove and sealed to the inner wall of the groove. An air outlet channel and an air inlet channel are formed inside the base. The air outlet is located on the side wall of the base and communicates with the annular sample cell through the air outlet channel. The air inlet is located on the side wall of the base and communicates with the annular sample cell through the air inlet channel. The openings of the air outlet channel and the air inlet channel within the annular sample cell are parallel. The positive terminal and the negative terminal are respectively embedded on both sides of the base. The positive terminal passes through the base and is electrically connected to the bottom of the positive inner rod. The top of the negative terminal passes through the base and is electrically connected to the bottom of the negative ring.

3. The plasma Raman in-situ cell according to claim 2, characterized in that, The cover assembly includes a cap pressing sheet, a cap, and a rubber ring. The rubber ring is annular, with one side tightly fitted to the bottom edge of the cap and the other side tightly fitted to the top opening face of the annular sample cell. Sliding guide structures are provided on the bases on both sides of the annular sample cell. The two cap pressing sheets are slidably mounted on the sliding guide structures, and the opposite sides of the two cap pressing sheets are pressed against the top two sides of the cap, so that the cap seals the top opening of the annular sample cell through the rubber ring.

4. The plasma Raman in-situ cell according to claim 3, characterized in that, The sliding guide structure is a threaded hole on the base. The pool cap pressure plate is provided with an elongated sliding hole extending in the sliding direction. The pool cap pressure plate is threaded to the threaded hole of the base by passing a fastening screw through the sliding hole. Tightening the fastening screw can fix the pool cap pressure plate on the base.

5. The plasma Raman in-situ cell according to claim 1, characterized in that, The top of the first quartz outer cover is integrally formed into a hemispherical structure, the top of the hemispherical structure is higher than the top of the inner rod of the positive electrode, and there is a gap of 0.1~0.5mm between the inner wall of the first quartz outer cover and the outer wall of the inner rod of the positive electrode; the top of the second quartz outer cover is flush with the top opening of the annular sample cell, and the inner wall of the second quartz outer cover is flush with the inner wall of the annular sample cell.

6. The plasma Raman in-situ cell according to claim 3, characterized in that, The pool cap is a one-piece molded structure made of transparent quartz material, and the rubber ring is a one-piece molded structure made of fluororubber material.

7. The plasma Raman in-situ cell according to claim 1, characterized in that, The inner rod of the positive electrode is a cylindrical structure with a central through hole.

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