Patent Application
20250191791
The present disclosure relates to the field of fusion reactors and relates generally to a method for controlling plasma edge fuel particle backflow by powder feedback injection, and more particularly to controlling edge fuel particle backflow by real-time powder feedback injection.
In the magnetic confinement nuclear fusion device, the strong heat flux and particle flux from the plasma with the high temperature of hundreds of millions degrees cause strong interaction between the particle flux and the wall directly facing the plasma. Part of the fuel particles rebound directly from the wall and re-enter the plasma. Another part of the fuel particles are retained on the wall surface by adsorption, ion implantation, co-deposition, etc., and are released from the wall and then returned into the plasma under the action of the plasma discharge particle and the heat fluxes. The process of these fuel particles re-entering the plasma from the action of the plasma and the wall is called recycling. It directly affects plasma density control, long-pulse high-parameter plasma acquisition and its confinement performance.
Various plasma-facing wall materials and their surface treatment and wall treatment techniques are continually being explored to reduce the release of fuel particles from the plasma wall surface and to reduce the level of particle recycling. The plasma-facing wall materials currently studied in tokamak devices are mainly graphite, tungsten, beryllium and so on. Graphite as a plasma wall material has several disadvantages, such as the need for long-term wall conditioning, chemical corrosion leading to reduced lifetimes, reduced physical and mechanical properties under neutron radiation, dust generation, fragmentation and damage under high heat load when the plasma is disruption, especially severe fuel retention leading to a large release of hydrogen isotopes during plasma discharge. Tungsten is also currently the material selected for the walls, but its widespread use may be affected by its high atomic number, which causes low tolerance content by the plasma, and its chemical attack and high activation by oxygen. Beryllium has a relatively low melting temperature, is potentially toxic, has a relatively high sputtering rate, and has limited applications, typically for plasma wall materials with low energy flux densities. Conventional wall conditionings include baking, DC glow discharge cleaning, ion cyclotron discharge cleaning, etc. The most common method is to raise the wall temperature, but the maximum baking temperature is limited by the sealing material and ambient conditions. Low-temperature plasma discharge cleaning techniques, such as low-energy DC glow discharge cleaning, and ion cyclotron discharge based on radio frequency technology, can remove fuel particles trapped in the walls. The glow discharge cleaning technology is well established, but it must work when the magnetic field of the device is very small, which severely limits its application in future superconducting tokamak devices. The ion cyclotron discharge cleaning can be used under very strong magnetic field conditions, suitable for the strong magnetic field environment of the superconducting tokamak device. However, these commonly used discharge cleaning techniques have difficulty in achieving complete removal of trapped fuel particles from the walls due to the relatively low power of the discharge cleaning. In order to further improve the compatibility of the wall with the high-temperature plasma and improve particle recycling, it is also necessary to coat the surface of the wall with a layer of low-atomic-number material. The commonly used coating materials are low-atomic-number materials such as silicon, boron and lithium which have good compatibility with the plasma. Meanwhile, EAST has developed a powder injection system that can be used to inject powder in real time during the plasma discharge process for the purpose of improving the wall conditions and thus reducing the level of recycling.
However, these wall conditioning methods can only be performed before the discharge and cannot be performed in real time during the discharge. At present, the method of powder injection can realize real-time recycling control in the discharge process. However, it can only preset the fixed flow value of powder injection, and can not adjust the flow according to the real-time recycling level in the experimental process. In this case, as the plasma pulse length of the fusion device is lengthened, the control of fuel particle recycling becomes more difficult. Because the fuel particles trapped in the wall will reach saturation as the pulse length is lengthened, and will be very easy to be released and re-enter the plasma during the rise fluctuation of the wall temperature, causing particle backflow, enhancing particle recycling, seriously restricting plasma density control in long pulse discharge, and even leading to the termination of discharge. It is difficult to achieve effective control of fuel recycling at the kilosecond long pulse scale by means of the existing first wall conditioning and fixed flow rate of powder injection, which severely limits the achievement of long pulse plasma discharge and the maintenance of steady state.
The present disclosure may remedy, among others, the deficiencies of the prior art by providing a method for controlling plasma edge fuel particle backflow by powder feedback injection to solve the problem of plasma long pulse fuel particle recycling control in fusion devices.
The present disclosure includes, among others, following technical solutions.
Step 1, the real-time Da value is measured by the visible spectrum diagnostic system, wherein the Da value qualitatively reflects the level of fuel recycling.
Step 2, in the plasma control system, the measured Da value is filtered by a low-pass filter, and a target Da value is set at the same time; and when an actual Da value is greater than the set target Da value, an output control voltage signal is calculated according to the PID algorithm formula, the greater the difference value, the greater the output voltage value. The magnitude of the output voltage ultimately determines the magnitude of the lithium powder injection flow rate. When the actual Da value is less than or equal to the set target Da value, the magnitude of the output voltage is 0.
Step 3, the voltage signal input by the PCS is converted into a sine wave signal by an amplitude mapping converter, and the same is output to the lithium powder injection system.
Step 4, the lithium powder injection system receives the voltage signal and injects the lithium powder into the fusion device. The injected lithium powder adsorbs the fuel particles generated by the interaction between the plasma and the wall, so that the backflow of the fuel particles is reduced, and the Da line emission intensity is also reduced. The above steps are repeated until the end of the discharge.
Furthermore, the visible spectrum diagnostic system is provided with reflectors on a upper part and a lower part of a horizontal window of the fusion device for detecting the intensity of the Da line emission at upper and lower divertor regions and part of the inner wall.
Still further, the plasma control system is a control system capable of running a control algorithm to realize plasma parameters on the basis of acquiring plasma parameter diagnostic information; and the PID algorithm formula is
wherein E(t)=Dα_set−Dα(t), Dα_set represents a set target value Da and Dα(t) represents a value of Da at a moment t. kp, ki, kd are a proportion, an integral and a difference parameter, respectively; and Y(t) is an output voltage value.
Furthermore, the amplitude mapping converter is configured for outputting an input signal as a sine wave signal with an amplitude value being the magnitude of a corresponding voltage value and a specific frequency, and is divided into a signal input module, a signal processing module, a signal output module and a display module, wherein the signal input module comprises a signal isolation amplifier and a resistor voltage division circuit, and the voltage value of the input signal is scaled to 0-3.3 V for collection by the signal processing module. The signal processing module collects the input voltage signal, and the collection port collects a point every 10 ms, and then the value of the point is taken as the amplitude of the sine wave signal to generate a sine wave with the amplitude magnitude and the frequency being 2250 HZ. 256 points are generated for each cycle until the next point is collected, and the above-mentioned process is repeated. The voltage signal input of 0-3.3V is converted into a sine wave voltage signal with a frequency of 2250 Hz and an amplitude value being the magnitude of the input voltage at the corresponding moment after passing through the signal processing module. The signal output module mainly realizes the functions of emitter-follower, filter and amplification of the output sinusoidal signal. The emitting-following and filter circuit is configured for eliminating noise in the generated analogue signal, and the amplification circuit is configured for rescaling the originally scaled voltage value to 0-5 V. The display module is configured for displaying the voltage value and the frequency of the output sine wave signal at the current moment.
Furthermore, the core component of the lithium powder injection system is a piezoelectric ceramic piece with a small circular hole in the middle; a bottom-through cylindrical container for storing lithium powder is located above the piezoelectric ceramic piece; and a conduit leading to the fusion device is connected below the piezoelectric ceramic piece. When a sine wave voltage is applied to the piezoelectric ceramic piece for vibration, the lithium powder slides towards the small circular hole and into the fusion device. The amplitude value of the sine wave voltage signal affects the vibration amplitude of the ceramic piece, thereby affecting the flow rate of lithium powder injection.
The disclosure has the advantages below.
The present disclosure controls the edge fuel particle backflow by the powder injection, and automatically adjusts a flow rate of the powder injection according to the real-time recycling level during the plasma discharge process so as to achieve real-time control of the fuel recycling. On the one hand, when the recycling level is low, the waste caused by excessive powder injection can be avoided. On the other hand, when the recycling level continues to rise, the powder injection flow rate can be increased, and the recycling level can be reduced, so as to reduce the backflow of fuel particles in the plasma discharge process, promote the realization of the scientific objectives of fusion devices and develop new ideas for the fuel particle control of the future fusion devices.
In the drawings, 1. fusion device; 2. lithium powder injection system; 3. plasma; 4. Da line emission; 5. visible spectrum diagnostic system; 6. plasma control system (PCS); 7. amplitude mapping converter; 8. wall.
The following is a clear and complete description of the technical solution in the embodiments of the present disclosure in combination with the drawings in the embodiments of the present disclosure. Obviously, the embodiments described are only a part of the embodiments of the present disclosure, but not all the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in the field without creative labor belong to the protection scope of the present disclosure.
As shown in
The amplitude mapping converter 7 is configured for outputting an input signal as a sine wave signal with an amplitude value being the magnitude of a corresponding voltage value and a specific frequency, and is divided into a signal input module, a signal processing module, a signal output module and a display module, wherein the signal input module comprises a signal isolation amplifier and a resistor voltage division circuit, and the voltage value of the input signal is scaled to 0-3.3V for collection by the signal processing module. The signal processing module collects an input voltage signal, a collection port collects a point every 10 ms, and then the value of the point is taken as the amplitude value of a sine wave signal to generate a sine wave with the amplitude value and the frequency being 2250 Hz all the time; 256 points are generated for each cycle until the next point is collected, and the above-mentioned process is repeated. The voltage signal input of 0-3.3V is converted into a sine wave voltage signal with a frequency of 2250 Hz and an amplitude value being the magnitude of the input voltage at the corresponding moment after passing through the signal processing module. The signal output module mainly realizes the functions of emitter-follower, filter and amplification of the output sinusoidal signal. The emitting-following and filter circuit is configured for eliminating noise in the generated analogue signal, and the amplification circuit is configured for rescaling the originally scaled voltage value to 0-5 V. The display module is configured for displaying the voltage value and the frequency of the output sine wave signal at the current moment.
The core component of the lithium powder injection system 2 is a piezoelectric ceramic piece with a small circular hole in the middle; a bottom-through cylindrical container for storing lithium powder is located above the piezoelectric ceramic piece; and a conduit leading to the fusion device is connected below the piezoelectric ceramic piece. When a sine wave voltage is applied to the piezoelectric ceramic piece for vibration, the lithium powder slides towards the small circular hole and into the fusion device. The amplitude value of the sine wave voltage signal affects the vibration amplitude of the ceramic piece, thereby affecting the flow rate of lithium powder injection.
Before the discharge starts, start time and end time for control algorithm execution are set in the plasma control system (6). During the discharge process, the intensity of the real-time Da line emission 4 is measured by the visible spectrum diagnostic system 5, and the magnitude of the intensity of the Da line emission 4 characterizes the level of recycling during the interaction between the plasma 3 and the wall 8. The plasma control system (PCS) 6 obtains the discharge start time of the fusion device 1, sets 1.5 times of the intensity of the Da line emission 4 3 s after the discharge start as a target value, and filters the measured Da value by a low-pass filter during the execution of the control algorithm. When the actual intensity of the Da line emission 4 is greater than the target value, the magnitude of the output voltage is calculated according to the PID algorithm formula. The PID algorithm formula is
wherein E(t)=Dα_set−Dα(t), Dα_set represents a set target value Da, and Dα(t) represents a value of Da at a moment t; kp, ki, kd are a proportion, an integral and a difference parameter, respectively; and Y(t) is an output voltage value.
The magnitude of the output voltage ultimately determines the magnitude of the flow rate of lithium powder injected into the lithium powder injection system 2. When the actual Da value is less than or equal to the set target Da value, the magnitude of the output voltage is 0, namely, the lithium powder injection system 2 does not inject lithium powder, and continuously outputs a signal of a voltage value with a corresponding magnitude to the amplitude mapping converter 7 according to the calculated value. After the amplitude mapping converter 7 receives the voltage signal transmitted by the plasma control system (PCS) 6, the collection port collects a point every 10 ms, and then the value of the point is taken as the amplitude of the sine wave signal to generate a sine wave with the amplitude magnitude and the frequency being 2250 HZ. 256 points are generated for each cycle until the next point is collected, and the above-mentioned process is repeated. Finally, it is converted into converted into a sine wave voltage signal with a frequency of 2250 Hz and an amplitude value being the magnitude of the input voltage at the corresponding moment, and output to the lithium powder injection system 2. The lithium powder injection system 2 receives the sine wave voltage signal. The magnitude of the sine wave voltage signal determines the flow rate of lithium powder injected into the fusion device 1. The injected lithium powder adsorbs the fuel particles generated by the interaction between the plasma 3 and the wall 8, so that the backflow of the fuel particles is reduced, and the Da line emission 4 intensity is also reduced. The above steps are repeated until the end of the control algorithm. By the above method, the flow rate of lithium powder injection is controlled according to the recycling level feedback of fuel particles characterized by the intensity of Da line emission 4, and the recycling of fuel particles is controlled by means of lithium powder feedback injection, which provides a new technical support for high-parameter, long-pulse steady-state operation of fusion devices.
Although the illustrative embodiments of the present disclosure have been described above for purposes of clarity of understanding to those of ordinary skill in the art, it should be understood that the present disclosure is not limited to the detailed description, and that various changes may be made which are obvious to those of ordinary skill in the art without departing from the spirit and scope of the present disclosure as defined and defined by the appended claims. All disclosures and creations utilizing the idea of the present disclosure fall in the protection scope of the present disclosure.
The various embodiments described above can be combined to provide further embodiments. Aspects of the embodiments can be modified, if necessary to employ concepts of the various embodiments to provide yet further embodiments.
These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202311688116.4 | Dec 2023 | CN | national |
