Ktx ultrasonic molecular beam injection system and quantitative measurement and ventilation method thereof

Abstract

The application discloses a KTX ultrasonic molecular beam injection system and a quantitative measurement and ventilation method thereof, and belongs to the technical field of magnetic confinement nuclear fusion experimental devices. The system comprises an SMBI body, parallel cooperation of an inflation circuit, a vacuum circuit and a gas exhaust circuit, and an insulation joint with fluid conduction and electrical isolation functions is connected in series between a pressure measuring assembly and a vacuum chamber. The gas purity is ensured through vacuum pre-extraction, in-situ disassembly-free gas replacement and secondary vacuum gas washing are realized by using an independent gas exhaust circuit, and a fixed-volume sampling steel cylinder is innovatively used in cooperation with a high-precision pressure transmitter to realize real-time calculation of the number of particles injected by a single electromagnetic pulse through a pressure drop method. The application effectively solves the problems of difficult accurate quantitative measurement of fusion charging and complicated pipeline switching and easy pollution in a strong electromagnetic interference environment, and significantly improves the precision of plasma density control and experimental continuity.

Description

Technical Field

[0001] This invention relates to the field of magnetic confinement fusion experimental device technology, specifically to a KTX ultrasonic molecular beam injection system and its quantitative measurement and gas exchange method, applied to the ultrasonic molecular beam injection (SMBI) system of the reverse field pinch magnetic confinement fusion experimental device (KTX). Background Technology

[0002] In magnetic confinement fusion research, one of the core challenges in achieving self-sustaining plasma combustion is the efficient and deep injection of fuel into the core of the high-temperature plasma to maintain high-density operating parameters. Ultrasonic molecular beam injection (SMBI), with its extremely high directional velocity and collimation, is a key method for improving plasma feeding depth and efficiency. However, current SMBI systems suffer from technical limitations such as incomplete pipe cleaning, the need to disassemble pipes for gas exchange, and the inability to accurately measure the injection volume per burst. Summary of the Invention

[0003] To address the challenges of precise quantitative measurement and cumbersome, contamination-prone pipeline switching in fusion reactors operating under strong electromagnetic interference, this invention provides a KTX ultrasonic molecular beam injection system and its quantitative measurement and gas exchange method. The system comprises an SMBI (Supersonic Molecular Beam Injection) unit and parallel, collaborative gas filling, vacuum, and exhaust circuits. An insulating connector providing both fluid conductivity and electrical isolation is connected in series between the pressure measurement component and the vacuum chamber. Vacuum pre-evacuation ensures gas purity, and an independent exhaust circuit enables in-situ, non-disassembly-based gas exchange and secondary vacuum purging. Innovatively, a fixed-volume sampling cylinder, coupled with a high-precision pressure gauge, is used to calculate the number of particles injected in a single electromagnetic pulse in real time using the pressure drop method. This invention significantly improves the accuracy of plasma density control and experimental continuity, offers resistance to electromagnetic interference, convenient and contamination-free gas exchange, and enables precise quantitative measurement of the number of particles injected in a single pulse.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A KTX ultrasonic molecular beam injection system, comprising:

[0006] An ultrasonic molecular beam injection body, comprising a Laval nozzle and a solenoid valve, wherein the outlet end of the ultrasonic molecular beam injection body is connected to a KTX vacuum chamber;

[0007] The inflation circuit includes a gas source interface, a pressure reducing valve, an inflation valve, a sampling cylinder and a pressure measuring component connected in sequence, and the outlet end of the inflation circuit is connected to the ultrasonic molecular beam injection body.

[0008] A vacuum circuit is connected to the inflation circuit, and its exhaust end is connected to the secondary vacuum system of the KTX device;

[0009] An exhaust circuit is connected to the inflation circuit and is equipped with an exhaust valve.

[0010] An insulating connector is connected in series on the pipeline between the pressure measuring component and the KTX vacuum chamber.

[0011] Furthermore, the insulating joint includes a stainless steel body, with a thermoplastic insulator and a fluororubber square sealing ring for fluid sealing inside.

[0012] Furthermore, the sampling cylinder is a double-ended high-pressure cylinder with a fixed nominal volume.

[0013] Furthermore, the pressure measurement component is an electronic pressure transmitter with a digital display and a communication interface.

[0014] Furthermore, the vacuum circuit is configured to pump air to a vacuum level below 10 Pa within the pipeline.

[0015] Furthermore, a sealing connection structure is provided between the Laval nozzle and the solenoid valve. This sealing connection structure uses a metal gasket to achieve a vacuum seal, and the Laval nozzle is fixed to the outlet end of the solenoid valve by threaded fasteners.

[0016] The present invention also provides a quantitative measurement and ventilation method based on the above-mentioned KTX ultrasonic molecular beam injection system, comprising the following steps:

[0017] Step S1: Open the vacuum circuit's evacuation valve and use the KTX device's secondary vacuum system to evacuate the gas filling circuit and the ultrasonic molecular beam injection body. Once the target vacuum level is reached, close the evacuation valve.

[0018] Step S2: Turn on the gas source. The gas enters the sampling cylinder through the pressure reducing valve and the filling valve in sequence. After the pressure in the sampling cylinder stabilizes, the initial pressure value P1 is read and recorded through the pressure measuring component.

[0019] Step S3: Trigger the solenoid valve of the ultrasonic molecular beam injection body to inject ultrasonic molecular beam into the KTX vacuum chamber according to the set parameters;

[0020] Step S4: After injection, read the remaining pressure value P2 in the sampling cylinder using the pressure measurement component, and calculate the pressure difference before and after injection. P=P1-P2, and combined with the fixed volume V of the sampling cylinder, the ambient temperature T, and the ideal gas constant R, the formula is used to... The amount of gas injected in a single pulse was calculated. n;

[0021] Step S5: When it is necessary to change the type of gas source, turn off the original gas source, open the exhaust valve on the exhaust circuit to release the residual gas in the pipeline, replace the new gas source without disassembling the main inflation pipeline and close the exhaust valve, and then repeat step S1 to complete the gas source switching.

[0022] Furthermore, in step S4, the pressure measurement component converts the read pressure signal into a digital signal and sends it to the host computer in real time through the communication interface for closed-loop calculation.

[0023] Furthermore, in steps S1 and S5, the secondary vacuum system evacuates the absolute pressure in the pipeline to below 10 Pa.

[0024] Furthermore, the sampling cylinder has a nominal volume of 150 mL, a nominal working pressure of not less than 20 MPa, and 1 / 4 NPT threaded interfaces at both ends.

[0025] Beneficial effects:

[0026] 1. To address the issue that strong transient currents during KTX device discharge can easily damage or distort precision pressure measuring elements, this invention constructs an anti-interference measurement structure combining a constant-volume sampling cylinder, an electronic pressure transmitter, and insulation isolation. By using a series insulating connector, the conduction current from the vacuum chamber side is completely cut off while ensuring the high-pressure fluid seal. This structure effectively protects the digital pressure measuring element, enabling it to maintain extremely high accuracy (≤0.5%FS) and fast response (≤5ms) even under strong discharge conditions. Therefore, based on the conventional voltage drop method, it safely and stably achieves transient capture and accurate quantitative measurement of the number of particles injected in a single short pulse.

[0027] 2. This invention integrates the three functional loops of gas filling, secondary vacuum extraction, and independent exhaust into a single system, overcoming the technical drawback of traditional SMBI systems that require disassembly of the main pipeline when changing the gas source. Based on this gas path topology, this invention further proposes a closed-loop gas exchange logic of in-situ exhaust, source replacement-free operation, and secondary pre-vacuuming. This effectively removes residual gas inside the pipeline and impurities introduced at the interface during gas exchange operations, significantly reducing the risk of cross-contamination between different experimental gases, thereby ensuring the purity of experimental gases and the continuity of physical experiments under high vacuum conditions. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the ultrasonic molecular beam formation and Laval nozzle flow field structure of the present invention.

[0029] Figure 2 This is a topology diagram of the three-loop gas path design of the KTX ultrasonic molecular beam injection system according to an embodiment of the present invention.

[0030] Figure 3A flowchart of a quantitative measurement and ventilation method provided in an embodiment of the present invention.

[0031] The reference numerals in the attached diagram are: 201-source gas cylinder; 202-source gas ball valve; 203-pressure reducing valve; 204-filling valve;

[0032] 205-Front-end needle valve; 206-Sampling cylinder; 207-Rear-end needle valve; 208-Pressure transmitter; 209-Insulating connector; 210-Bellbell; 211-KTX vacuum chamber; 212-Exhaust valve; 213-Pump valve; 214-Vacuum gauge; 215-Secondary vacuum interface; 101-Laval nozzle; 101a-Contraction section; 101b-Throat; 101c-Expansion section; 102-Jet boundary; 103-Rare shock wave region; 104-Mach wave shock wave region; 105-Quiet region. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0034] like Figure 1 , Figure 2 As shown, a KTX ultrasonic molecular beam injection system of the present invention includes:

[0035] The SMBI body includes a Laval nozzle 101 and a solenoid valve, and the outlet end of the SMBI body is connected to the KTX vacuum chamber 211.

[0036] The inflation circuit includes an air source interface, a pressure reducing valve 203, an inflation valve 204, a sampling cylinder 206 and a pressure transmitter 208 connected in sequence, and the outlet end of the inflation circuit is connected to the SMBI body.

[0037] A vacuum circuit, connected to the gas filling circuit, and whose exhaust end is connected to the secondary vacuum interface 215 of the secondary vacuum system of the KTX device, is used to purge residual gas in the system before gas injection.

[0038] An exhaust circuit, connected to the inflation circuit, is equipped with an exhaust valve 212 for discharging gas from the pipeline to allow for the replacement of the gas source type.

[0039] An insulating connector 209 is connected in series on the pipeline between the pressure measuring component and the KTX vacuum chamber 211. It is used to block the conduction current while allowing unimpeded gas flow, so as to protect the monitoring instrument from the influence of the current and protect the pressure measuring component.

[0040] Specifically, such as Figure 1 As shown, the Laval nozzle 101 includes a contraction section 101a, a throat 101b, and an expansion section 101c. After the high-pressure gas is ejected through the Laval nozzle 101, a closed jet boundary 102 is formed on the outside. The jet boundary 102 contains a rarefied shock region 103 and forms a vertical Mach wave shock region 104 in front of it. The central region formed by the outlet of the Laval nozzle 101, the rarefied shock region 103, and the Mach wave shock region 104 is the isentropic region (i.e., the quiet region 105).

[0041] like Figure 2 As shown, the source gas cylinder 201 is connected to the pressure reducing valve 203 via the gas source ball valve 202. The main pipeline after the pressure reducing valve 203 is divided into three circuits: gas filling, vacuum, and gas exhaust. The main pipeline between the gas filling valve 204 and the front needle valve 205 leads to the exhaust branch and the vacuum branch, which are connected to the exhaust valve 212 and the suction valve 213, respectively. The suction valve 213 is connected to the vacuum gauge 214 and then to the secondary vacuum interface 215. The main gas filling pipeline is connected to the input end of the sampling cylinder 206 via the front needle valve 205. The output end of the sampling cylinder 206 is connected to the pressure transmitter 208 and the rear needle valve 207 of the main pipeline via the rear tee interface. Then the pipeline is connected in series with the insulating joint 209 and finally connected to the KTX vacuum chamber 211 via the bellows 210.

[0042] Preferably, the insulating joint 209 comprises a stainless steel body, with an internal thermoplastic insulator and a fluororubber square sealing ring for fluid sealing. During operation of the KTX device, extremely strong currents and transient electromagnetic fields are generated. To protect the high-precision pressure transmitter 208 from current surges, the insulating joint 209 is installed in series on the main pipeline connecting the pressure transmitter 208 to the KTX vacuum chamber 211.

[0043] Preferably, the sampling cylinder 206 is a double-ended high-pressure cylinder with a fixed nominal volume.

[0044] Preferably, the pressure measurement component is a pressure transmitter 208 with a digital display and a communication interface.

[0045] Specifically, in this invention, high-pressure gas, driven by the internal and external pressure difference, undergoes isentropic expansion through the Laval nozzle 101 to form a supersonic beam comprising a rarefied shock wave region 103, a Mach wave shock wave region 104, and a quiet region 105, achieving deep feeding. The peripheral gas path is divided into three main loops:

[0046] Vacuum circuit: Primarily used for filling and emptying applications. Before gas injection, the evacuation valve 213 is opened, and residual gas in the system is emptied through the secondary vacuum system connected to the KTX device, reaching a pressure below 10 Pa. A vacuum gauge 214 is installed on the vacuum circuit for real-time monitoring.

[0047] Exhaust circuit: Includes exhaust valve 212 and exhaust port. When it is necessary to change the gas type, the residual gas in the pipeline can be directly discharged through this exhaust circuit without disassembling any hardware.

[0048] Gas filling circuit: Gas enters a calibrated volume (e.g., 150ml) sampling cylinder via pressure reducing valve 203 and filling valve 204. Pressure values ​​are read by a pressure transmitter connected to the pipeline. To protect the measuring and control equipment from interference from the strong electromagnetic field environment of the KTX device, an insulating connector 209 is specially installed on the pipeline connected to the KTX vacuum chamber 211 after the pressure gauge.

[0049] Preferably, the thermoplastic insulator inside the insulating joint 209 has a resistance value of not less than 10 × 10⁻⁶ under a 10V DC voltage. 6 Ω.

[0050] Preferably, the electronic pressure transmitter is electrically connected to the outside via an M12x1 circular plug, and its contact parts with the detected gas are made of 316L stainless steel.

[0051] Preferably, the vacuum circuit is configured to pump air to a vacuum level below 10 Pa within the pipeline.

[0052] Preferably, the sampling cylinder 206, which serves as the constant volume container in the inflation circuit, is a double-ended high-pressure small cylinder from the FINELOK brand. Its specific specifications are: nominal volume 150mL, nominal outer diameter 51mm, and nominal working pressure up to 20MPa, capable of withstanding stringent experimental inflation pressures. Both ends use standard 1 / 4NPT threads to ensure high-pressure airtightness.

[0053] Preferably, the pressure transmitter 208 used in conjunction with the sampling cylinder 206 is a WIKA brand PSD-4 electronic pressure transmitter with a digital display. This electronic pressure transmitter not only features an intuitive 14-segment LED red display screen, but also boasts a measurement accuracy of up to 0.5%FS. More importantly, this transmitter supports the IO-Link 1.1 communication standard, enabling the transmission of pressure difference data before and after inflation to the acquisition system with extremely low latency (stabilization time ≤5ms), achieving transient and accurate calculation of the injection volume.

[0054] Preferably, the insulating connector 209 is a high-voltage insulating connector from the Swagelok brand. The body is machined from 316 stainless steel, and the internal components utilize a high-voltage resistant polyimide-amide thermoplastic insulator and a fluororubber FKM square sealing ring. This connector provides a 5000psig pressure-bearing seal while also providing 10×10 psi at 10V DC voltage. 6 With an insulation resistance of Ω, unimpeded gas conduction and absolute electrical isolation are achieved.

[0055] Preferably, a vacuum valve 213 and a vacuum gauge 214 are configured on the vacuum circuit, with one end connected to the main gas charging line and the other end connected to the secondary vacuum system of the KTX device. Its pumping capacity can pre-pump the system pipeline vacuum to below 10 Pa.

[0056] like Figure 3 As shown, the present invention also provides a quantitative measurement and ventilation method for a KTX ultrasonic molecular beam injection system, comprising the following steps:

[0057] Step S1, Vacuum pre-evacuation: Open the vacuum circuit pump valve 213, use the secondary vacuum system of the KTX device to evacuate the gas charging circuit and SMBI body, and close the pump valve 213 after the target vacuum level is reached.

[0058] Step S2, Volumetric filling and initial pressure measurement: Open the source gas cylinder 201, and the gas enters the sampling cylinder 206 through the pressure reducing valve 203 and the filling valve 204 in sequence; after the pressure in the sampling cylinder 206 stabilizes, the initial pressure value P1 is read and recorded by the pressure transmitter 208.

[0059] Step S3, Pulse Injection: Trigger the solenoid valve of the SMBI body to inject ultrasonic molecular beams into the KTX vacuum chamber 211 according to the set pulse width, duty cycle and number of pulses;

[0060] Step S4, Residual Pressure Measurement and Quantitative Calculation: After injection, the residual pressure value P2 in the sampling cylinder 206 is read through the pressure transmitter 208; the pressure difference before and after injection is calculated. P=P1-P2, and combined with the fixed volume V of the sampling cylinder 206, the ambient temperature T, and the ideal gas constant R, the formula is used to... The amount of gas injected in a single pulse was calculated. n (unit is mole (mol));

[0061] Step S5, Gas Replacement Without Disassembly: When it is necessary to change the gas source type, close the source gas cylinder 201, open the exhaust valve 212 on the exhaust circuit, and discharge most of the residual gas in the pipeline; without disassembling the main filling pipeline, replace the new gas source at the interface of the source gas cylinder 201, and close the exhaust valve 212; then repeat step S1, that is, open the vacuum valve 213 of the vacuum circuit, and use the secondary vacuum system of the KTX device to perform vacuum extraction on the pipeline again, completely purging the impurity gas and residual gas mixed in at the interface when replacing the source gas cylinder 201, and close the vacuum valve 213 after reaching the target vacuum level to complete the gas source switching.

[0062] Preferably, in step S4, the pressure measurement component converts the read pressure signal into a digital signal and sends it to the host computer in real time via the communication interface for closed-loop calculation.

[0063] Preferably, in steps S1 and S5, the secondary vacuum system of the KTX device can reduce the absolute pressure in the pipeline to below 10 Pa.

[0064] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A KTX ultrasonic molecular beam injection system, characterized in that, include: An ultrasonic molecular beam injection body, comprising a Laval nozzle and a solenoid valve, wherein the outlet end of the ultrasonic molecular beam injection body is connected to a KTX vacuum chamber; The inflation circuit includes a gas source interface, a pressure reducing valve, an inflation valve, a sampling cylinder and a pressure measuring component connected in sequence, and the outlet end of the inflation circuit is connected to the ultrasonic molecular beam injection body. A vacuum circuit is connected to the inflation circuit, and its exhaust end is connected to the secondary vacuum system of the KTX device; An exhaust circuit is connected to the inflation circuit and is equipped with an exhaust valve. An insulating connector is connected in series on the pipeline between the pressure measuring component and the KTX vacuum chamber.

2. The KTX ultrasonic molecular beam injection system according to claim 1, characterized in that: The insulating joint includes a stainless steel body, an internal thermoplastic insulator, and a fluororubber square sealing ring for fluid sealing.

3. The KTX ultrasonic molecular beam injection system according to claim 1, characterized in that: The sampling cylinder is a double-ended high-pressure cylinder with a fixed nominal volume.

4. The KTX ultrasonic molecular beam injection system according to claim 1, characterized in that: The pressure measurement component is an electronic pressure transmitter with a digital display and a communication interface.

5. The KTX ultrasonic molecular beam injection system according to claim 1, characterized in that: The vacuum circuit is configured to pump air to a vacuum level below 10 Pa within the pipeline.

6. The KTX ultrasonic molecular beam injection system according to claim 1, characterized in that: A sealing connection structure is provided between the Laval nozzle and the solenoid valve. This sealing connection structure uses a metal gasket to achieve a vacuum seal, and the Laval nozzle is fixed to the outlet end of the solenoid valve by threaded fasteners.

7. A quantitative measurement and ventilation method based on the KTX ultrasonic molecular beam injection system according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step S1: Open the vacuum circuit's evacuation valve and use the KTX device's secondary vacuum system to evacuate the gas filling circuit and the ultrasonic molecular beam injection body. Once the target vacuum level is reached, close the evacuation valve. Step S2: Turn on the gas source. The gas enters the sampling cylinder through the pressure reducing valve and the filling valve in sequence. After the pressure in the sampling cylinder stabilizes, the initial pressure value P1 is read and recorded through the pressure measuring component. Step S3: Trigger the solenoid valve of the ultrasonic molecular beam injection body to inject ultrasonic molecular beam into the KTX vacuum chamber according to the set parameters; Step S4: After injection, read the remaining pressure value P2 in the sampling cylinder using the pressure measurement component, and calculate the pressure difference before and after injection. P=P1-P2, and combined with the fixed volume V of the sampling cylinder, the ambient temperature T, and the ideal gas constant R, the formula is used to... The amount of gas injected in a single pulse was calculated. n; Step S5: When it is necessary to change the type of gas source, turn off the original gas source, open the exhaust valve on the exhaust circuit to release the residual gas in the pipeline, replace the new gas source without disassembling the main inflation pipeline and close the exhaust valve, and then repeat step S1 to complete the gas source switching.

8. The quantitative measurement and ventilation method according to claim 7, characterized in that: In step S4, the pressure measurement component converts the read pressure signal into a digital signal and sends it to the host computer in real time through the communication interface for closed-loop calculation.

9. The quantitative measurement and ventilation method according to claim 7, characterized in that: In steps S1 and S5, the secondary vacuum system evacuates the vacuum level in the pipeline to below 10 Pa.

10. The quantitative measurement and ventilation method according to claim 7, characterized in that: The sampling cylinder has a nominal volume of 150 mL, a nominal working pressure of not less than 20 MPa, and 1 / 4 NPT threaded interfaces at both ends.

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