CN116906297B

CN116906297B - Low-temperature pump rapid regeneration system and method suitable for tokamak steady-state operation

Info

Publication number: CN116906297B
Application number: CN202311170468.0A
Authority: CN
Inventors: 宋云涛; 陈肇玺; 陈仕琳; 杨庆喜; 余清洲; 张程鹏; 于志航
Original assignee: Hefei Institutes of Physical Science of CAS
Current assignee: Hefei Institutes of Physical Science of CAS
Priority date: 2023-09-12
Filing date: 2023-09-12
Publication date: 2023-12-08
Anticipated expiration: 2043-09-12
Also published as: CN116906297A

Abstract

The embodiment of the invention provides a low-temperature pump rapid regeneration system and a method suitable for Tokamak steady-state operation, wherein the system comprises a low-temperature pump, a mechanical pump, a mass spectrometer, an adjustable radio frequency source and a system controller; the mass spectrometer monitors the gas content in the cryopump; the low-temperature cold plate in the low-temperature pump comprises a stainless steel plate layer with a nickel layer plated on one side, and an adsorbent is arranged on the outer side of the nickel layer; the system controller controls and adjusts the working parameters of the adjustable radio frequency source according to the judgment result of the temperature signal; the adjustable radio frequency source provides current to the induction coil, and the magnetic field generated by the induction coil causes the low temperature Leng Ban to generate current and the temperature to rise; the low-temperature pump regeneration system heats the low-temperature cold plate through induction heating and utilizes the skin effect of induction current to realize the rapid temperature rise of the surface layer of the low-temperature cold plate, thereby enabling the low-temperature pump to regenerate rapidly. In addition, according to the temperature signal transmitted by the temperature sensor, the temperature of the low temperature Leng Ban can be accurately controlled during desorption of the low temperature pump by adjusting the working parameters of the adjustable radio frequency source.

Description

Low-temperature pump rapid regeneration system and method suitable for tokamak steady-state operation

Technical Field

The invention relates to the technical field of low-temperature vacuum, in particular to a low-temperature pump rapid regeneration system and a method suitable for steady-state operation of tokamak.

Background

In the field of fusion research, tokamak is a type of nuclear fusion device which is widely studied at present, has great application potential and is considered as one of clean and sustainable energy solutions in the future. In tokamak devices, an ultra-high vacuum environment needs to be achieved to ensure free movement of energetic ions in the plasma, thereby achieving a nuclear fusion reaction. Therefore, the vacuum pumping system has important application significance in a tokamak device.

The main function of the vacuum pumping system in the tokamak device is to create and maintain an ultra-high vacuum environment by pumping gas so as to ensure stable operation of plasma. The control of gas flux, particularly helium ash control generated by the deuterium-tritium fusion reaction, is one of the key problems affecting fusion reactor performance and steady state operation. The cryopump is used as a common pumping device, has the obvious advantages of high pumping speed for hydrogen isotopes, helium and different impurities, and the like, and besides, the cryopump also has obvious anti-interference capability for background magnetic fields and neutron irradiation of tokamaks. ITER, EAST, JET and other globally known large-scale tokamak devices all adopt a cryopump as a plasma pumping mode, and the cryopump is also recognized as a reactor core pumping system of a future fusion reactor.

The running period of the cryopump is divided into two independent stages of pumping and regeneration. In tokamak plasma experiments, a tokamak cryopump maintains a vacuum environment of a plasma by pumping gas in the plasma. In the pumping process, unburned deuterium-tritium fuel and fusion helium ash are "captured" by a 4.5K low-temperature adsorption plate in a low-temperature adsorption or low-temperature condensation mode, so that stable operation of plasma is maintained. As the pumping time of the cryopump is prolonged, the cryoporption or cryocondensation gradually reaches saturation, thereby reducing the pumping efficiency of the cryopump. In order to restore the pumping performance of the cryopump, periodic regeneration of the cryopump is required. Multiple sets of cryopumps are required to be installed on the tokamak, and at any moment, one half of the cryopumps are in an air extraction mode, and the other half of the cryopumps are in a regeneration mode. The low-temperature pumps work and regenerate continuously and alternately, so that high-flow high-efficiency air extraction can be realized, and steady-state operation of the tokamak is ensured. Meanwhile, the total quantity of the cryopumps can be effectively reduced by shortening the regeneration time of the cryopumps, and the method has important significance for steady-state safe operation of tokamaks.

Concretely, the pyrolysis regeneration mode of the low-temperature pump is divided into a natural temperature return regeneration mode, a hot gas flushing regeneration mode and an electric heating regeneration mode. The traditional regeneration mode has limitation on heating efficiency, cannot meet the requirement of rapid regeneration, and can cause high tritium retention and tritium loss due to long time, because hydrogen isotopes are easy to decay, the regeneration time is too long, the hydrogen isotopes can not be recycled after being easy to decay, and the operation efficiency and the economy of the fusion reactor are not facilitated. In addition, although the electric heating regeneration mode has a higher heating rate, the controllability of the temperature of the cryogenic cold plate in the cryopump is poor.

Disclosure of Invention

The embodiment of the invention provides a low-temperature pump rapid regeneration system and a method suitable for Tokamak steady-state operation, which are used for solving the problems of long regeneration time and poor heating temperature controllability in the related technology.

The embodiment of the invention provides a low-temperature pump rapid regeneration system suitable for tokamak steady-state operation, which is characterized by comprising a low-temperature pump, a mechanical pump, a mass spectrometer, an adjustable radio frequency source and a system controller, wherein the low-temperature pump rapid regeneration system is applied to a tokamak device;

the low-temperature pump is connected with the vacuum chamber of the tokamak device and is used for condensing gas in the vacuum chamber and adsorbing reaction products so as to ensure the vacuum degree of the vacuum chamber;

the mass spectrometer is connected between the cryogenic pump and the system controller and is used for monitoring the gas content in the cryogenic pump so as to judge the air extraction effect and the regeneration process of the cryogenic pump;

the low-temperature pump comprises a pump shell and low-temperature cold plates distributed in a circumferential array in the pump shell, a valve is arranged at the first end of the pump shell, and the system controller is used for controlling the opening and closing of the valve according to the air extraction effect and the regeneration process so as to control the inflow of the air; the low-temperature cold plate comprises a stainless steel plate layer with a nickel layer plated on one side, wherein an adsorbent is arranged on the outer side of the nickel layer and is used for adsorbing the gas and the reaction product to the surface of the adsorbent;

The cryopump further comprises at least one temperature sensor, wherein the temperature sensor is used for monitoring the temperature of at least one structure in the cryopump and generating a temperature signal;

the temperature sensor is connected with the system controller and transmits the temperature signal to the system controller;

the system controller is connected with the adjustable radio frequency source, and is used for judging the temperature signal and controlling and adjusting the working parameters of the adjustable radio frequency source according to the judging result;

the adjustable radio frequency source is also electrically connected with an induction coil which is spirally connected with the periphery of the low-temperature cold plate; the adjustable radio frequency source is used for providing current to the induction coil so that the induction coil generates a magnetic field; the magnetic field acts on the low-temperature cold plate to enable the low-temperature cold plate to generate induced current to increase the temperature, so that the gas adsorbed on the low-temperature cold plate is desorbed;

the second end of the pump shell is also provided with an exhaust port, and the mechanical pump is communicated with the interior of the cryopump through the exhaust port; the mechanical pump is used for pumping the desorbed gas in the cryopump through the vent after the cryopump is regenerated;

And a first cooling channel is arranged in the low-temperature cold plate and is used for reducing the temperature of the low-temperature cold plate after a first cooling medium is introduced, so that the low-temperature pump regains the air suction capacity.

Optionally, the cryopump further includes a push assembly, a cold shield, and a radiation shield;

the cold screen is positioned between the pump shell and the induction coil and is used for absorbing Joule heat generated by electrifying the induction coil on one hand and isolating heat radiation outside the pump shell on the other hand;

the radiation baffle is positioned at the inner side of the cryogenic cold plate and is used for precooling the gas entering the cryogenic pump;

the pushing component is connected with the valve and used for controlling the opening and closing of the valve.

Optionally, the cryopump further comprises a coil clamping structure for fixing the induction coil;

the coil clamping structure comprises a base and a clamp which is matched with the base for installation; when the base is matched with the clamp for installation, the induction coil is clamped between the base and the clamp;

the position of the base, the clamp and the induction coil are provided with a ceramic cylinder, and the ceramic cylinder is used for isolating the coil clamping structure from the induction coil when the induction coil is electrified.

Optionally, a pressure sensor and a pressure relief valve arranged at the second end of the pump shell are further arranged in the cryogenic pump, and the pressure relief valve is communicated with the interior of the cryogenic pump through a pressure relief valve interface arranged at the second end of the pump shell;

the pressure sensor is connected with the system device and is used for monitoring a pressure signal in the system and transmitting the pressure signal to the system controller;

and the system controller is used for adjusting the working parameters of the adjustable radio frequency source or controlling the opening and closing of the pressure relief valve after receiving the pressure signal.

Optionally, the induction coil and the adjustable radio frequency source further comprise an impedance matching unit connected between the induction coil and the adjustable radio frequency source, wherein the impedance matching unit is used for matching the impedance of the induction coil and the adjustable radio frequency source so as to maximize energy transmitted by the adjustable radio frequency source to the induction coil.

Optionally, the cryopump further includes an electrode flange disposed at a second end of the pump housing;

a second cooling channel for circulating a second cooling medium is also arranged in the induction coil; the induction coil passes through the electrode flange, and a coil leading-out section is reserved at one side of the electrode flange; the coil leading-out section is a part of the induction coil and is used for being connected with an external water chiller, and circulating a second cooling medium in the second cooling channel and a second cooling medium of the external water chiller so as to take away joule heat generated by the induction coil;

The electrode flange is provided with an electrode interface connected with the coil leading-out section, and the electrode interface is used for leading current generated by the adjustable radio frequency source into the induction coil.

The embodiment of the invention also provides a low-temperature pump rapid regeneration method suitable for the steady-state operation of the tokamak, which comprises the following steps:

after the low Wen Bengfa door is controlled to be opened, under the condition that a vacuum chamber and an air extraction system channel are opened, acquiring the first gas content in the cryopump acquired by a mass spectrometer;

determining whether the first gas content reaches a preset value; the preset value is stored in a control program of a system controller;

when the first gas content is determined to reach the preset value, controlling the valve to be closed;

controlling the adjustable radio frequency source to be turned on so that a magnetic field generated by the induction coil causes the low temperature Leng Ban to generate induction current to raise the temperature;

controlling a mechanical pump to be started so as to pump the low-temperature pump with gas, and discharging the gas generated in the low-temperature pump;

monitoring the temperature of the low-temperature cold plate through a temperature sensor, and adjusting the parameters of the adjustable radio frequency source according to the monitoring result;

acquiring a change in the content of a second gas in the cryopump within a preset first period of time from the mass spectrometer;

And determining whether the low-temperature pump completes a desorption stage according to the change condition of the second gas content, and after determining that the desorption stage is completed, introducing a first cooling medium into a first cooling channel of the low-temperature cold plate so as to reduce the temperature of the low-temperature cold plate to a preset adsorption temperature, so that the low-temperature pump regains the pumping capacity.

Optionally, the monitoring the temperature of the cryocooler, and adjusting the parameter of the adjustable radio frequency source according to the monitoring result specifically includes:

acquiring a temperature signal of low temperature Leng Ban transmitted by a temperature sensor, and determining whether the temperature of the low-temperature cold plate reaches the target desorption temperature of the gas according to the temperature signal;

when it is determined that the temperature signal has not reached the target desorption temperature, the current of the adjustable radio frequency source is adjusted to increase the heat of induction of the induction coil on the cryocooler.

Optionally, the method is characterized in that the determining whether the cryogenic pump completes the desorption stage according to the change condition of the second gas content specifically includes:

determining that a desorption phase of the cryopump is incomplete when the second gas content varies;

when the second gas content is unchanged, determining that the desorption phase of the cryopump is complete.

The embodiment of the invention has at least the following beneficial effects:

the embodiment of the invention provides a low-temperature pump rapid regeneration system and a method suitable for tokamak steady-state operation, which are applied to a tokamak device and comprise a low-temperature pump, a mechanical pump, a mass spectrometer, an adjustable radio frequency source and a system controller; the low-temperature pump is connected with the vacuum chamber of the tokamak device and is used for condensing gas in the vacuum chamber and adsorbing reaction products so as to ensure the vacuum degree of the vacuum chamber; the mass spectrometer is connected between the cryogenic pump and the system controller and is used for monitoring the gas content in the cryogenic pump so as to judge the air extraction effect and the regeneration process of the cryogenic pump; the low-temperature pump comprises a pump shell and low-temperature cold plates distributed in a circumferential array in the pump shell, a valve is arranged at the first end of the pump shell, and the system controller is used for controlling the opening and closing of the valve according to the air extraction effect and the regeneration process so as to control the inflow of the air; the low-temperature cold plate comprises a stainless steel plate layer with a nickel layer plated on one side, wherein an adsorbent is arranged on the outer side of the nickel layer and is used for adsorbing the gas and the reaction product to the surface of the adsorbent; the cryopump further comprises at least one temperature sensor, wherein the temperature sensor is used for monitoring the temperature of at least one structure in the cryopump and generating a temperature signal; the temperature sensor is connected with the system controller and transmits the temperature signal to the system controller; the system controller is connected with the adjustable radio frequency source, and is used for judging the temperature signal and controlling and adjusting the working parameters of the adjustable radio frequency source according to the judging result; the adjustable radio frequency source is also electrically connected with an induction coil which is spirally connected with the periphery of the low-temperature cold plate; the adjustable radio frequency source is used for providing current to the induction coil so that the induction coil generates a magnetic field; the magnetic field acts on the low-temperature cold plate to enable the low-temperature cold plate to generate induced current to increase the temperature, so that the gas adsorbed on the low-temperature cold plate is desorbed; the second end of the pump shell is also provided with an exhaust port, and the mechanical pump is communicated with the interior of the cryopump through the exhaust port; the mechanical pump is used for pumping the desorbed gas in the cryopump through the vent after the cryopump is regenerated; the low-temperature pump regeneration system heats the low-temperature cold plate through induction heating, and realizes rapid temperature rise of the surface layer of the low-temperature cold plate by using the skin effect of induced current, so that the low-temperature pump is regenerated rapidly. In addition, according to the temperature signal transmitted by the temperature sensor, the temperature of the low temperature Leng Ban can be accurately controlled during desorption of the low temperature pump by adjusting the working parameters of the adjustable radio frequency source.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a connection of a cryopump rapid regeneration system adapted for steady state operation of a Tokamak according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a cryopump according to an embodiment of the present invention;

FIG. 3 is a cross-sectional view of a low temperature Leng Ban provided by an embodiment of the present invention;

fig. 4 is a schematic diagram of a coil clamping structure according to an embodiment of the present invention;

FIG. 5 is a schematic view of an electrode flange assembly according to an embodiment of the present invention;

FIG. 6 is a flow chart of a method for rapid regeneration of a cryopump suitable for steady state operation of tokamak according to an embodiment of the present invention;

fig. 7 is a graph comparing a heating curve of a low temperature Leng Ban of nickel-plated stainless steel with a heating curve of a low temperature Leng Ban of stainless steel based on an induction heating method according to an embodiment of the present invention.

Reference numerals:

1-a valve; 2-pump shell; 3-cooling screen; 4-an induction coil clamping structure; a 5-induction coil; 6-a low-temperature cold plate; 601-adsorbent; 602-a nickel layer; 603-stainless steel plate layer; 604-a first cooling channel; 7-a radiation shadow mask; 401-a clamp; 402-a first bolt assembly; 403-a first insulating ceramic cylinder; 404-a base; 8-pushing assembly; 9-electrode flange; 901-a second bolt assembly; 902-an electrode flange cover; 903—a second insulating ceramic cylinder; 501-a cooling loop interface; 502-electrode interface; 10-exhaust port; 11-a cylinder assembly; 12-pressure relief valve interface.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Fig. 1 is a schematic connection diagram of a rapid regeneration system of a cryopump suitable for steady state operation of a tokamak according to an embodiment of the present invention. As shown in fig. 1, comprises a cryopump, a mechanical pump, a mass spectrometer, an adjustable radio frequency source and a system controller;

the mass spectrometer is connected between the cryopump and the system controller and is used for monitoring the gas content in the cryopump so as to judge the pumping effect and the regeneration process of the cryopump.

Specifically, when the tokamak device is operated, deuterium and tritium gas is used as a reaction fuel, and helium ash is generated after the deuterium and tritium is reacted. The vacuum chamber inside the tokamak device is provided with unreacted deuterium-tritium gas and reaction product helium ash, the cryopump is connected with the vacuum chamber of the tokamak, and the unreacted deuterium-tritium gas and the reaction product helium ash in the vacuum chamber are adsorbed to ensure the vacuum degree of the vacuum chamber so that the tokamak device can normally and stably operate.

The cryogenic pump is used for desorbing the adsorbed deuterium-tritium gas and the reaction product helium ash during regeneration after the unreacted deuterium-tritium gas and the reaction product helium ash are adsorbed, and a mechanical pump connected with the cryogenic pump is used for pumping the desorbed deuterium-tritium gas and the reaction product helium ash out of the cryogenic pump. The mechanical pump pumps the adsorbed deuterium-tritium fuel and helium ash from the cryopump by providing sufficient gas flow rate and pressure differential.

The mass spectrometer is connected to the cryopump, so that the deuterium-tritium partial pressure in the cryopump, namely the content of deuterium-tritium gas, can be monitored, and whether the cryopump still has a good air extraction effect can be judged according to the content of deuterium-tritium gas in the cryopump. When the adsorption capacity of the cryopump approaches saturation, the content of deuterium-tritium gas in the cryopump is gradually increased, and the pumping effect of the cryopump is poorer, so that the content of deuterium-tritium gas in the cryopump needs to be monitored by a mass spectrometer to judge the pumping effect of the cryopump. In addition, in the desorption process, more and more gas is desorbed in the cryopump, and when the desorption is approaching to completion, the content change of deuterium-tritium gas in the cryopump is smaller and smaller until no change occurs, so that the mass spectrometer can also be used for monitoring the desorption process to what extent.

The adjustable radio frequency source is an excitation source, and the frequency and the power can be adjusted to control the depth and the uniformity of induction heating. The adjustable radio frequency source has the characteristics of adjustable output power, adjustable frequency and adjustable working mode. The working modes comprise continuous working and pulse working modes, and the various protection functions comprise overcurrent protection, overvoltage protection and over-temperature protection.

The system controller is connected and communicated with a plurality of components in the system, and coordinates and controls the operation of the whole system.

the system controller is connected with the adjustable radio frequency source, and is used for judging the temperature signal and controlling and adjusting the working parameters of the adjustable radio frequency source according to the judging result.

Specifically, fig. 2 is a schematic structural diagram of a cryopump according to an embodiment of the present invention.

As shown in fig. 2, a plurality of cryogenic cold plates 6 distributed in a circumferential array are installed inside the pump housing 2 of the cryopump, and the plurality of cryogenic cold plates 6 are arranged in the cryopump body in a manner of being inclined at a certain included angle, so that the whole cryopump system can accommodate more cold plates in a limited space, thereby increasing the adsorption area of the adsorbent 601. The arrangement fully utilizes the internal space of the cryopump, optimizes the performance of the system and improves the adsorption effect. One end of the low Wen Bengdi is provided with a valve 1, and when the valve 1 is opened, deuterium-tritium fuel and helium ash in the vacuum chamber can enter the cryopump through the valve 1 and then are adsorbed by the cryopanel 6. When the capacity of the cryogenic cold plate 6 for absorbing gas is saturated, the valve 1 is closed, the circulation of gas between the inside of the cryogenic pump and the vacuum chamber is blocked, and meanwhile, the system controller controls the other group of cryogenic pumps to be opened for exhausting the vacuum chamber. The opening and closing of the valve 1 is controlled by a system controller.

Fig. 3 is a cross-sectional view of a low temperature Leng Ban provided by an embodiment of the present invention.

As shown in fig. 3, the low-temperature cold plate 6 has a three-layer structure of a stainless steel plate layer 603, a nickel layer 602 plated on one side of the stainless steel plate layer 603, and an adsorbent 601 attached to the outside of the nickel layer 602, respectively. The adsorbent 601 may be activated carbon or molecular sieves. Because eddy current generated by induction heating is mainly concentrated near the metal surface, a skin effect is formed, so that the heating rate of the surface temperature of the cryogenic cold plate 6 is significantly increased. The skin effect is that when an alternating electromagnetic field is present in the conductor, the current distribution inside the conductor is uneven and the current is concentrated in the "skin" portion of the conductor, i.e. the current is concentrated in a thin layer on the surface of the conductor, the closer to the surface of the conductor the higher the current density, the smaller the current actually flows inside the conductor. Since the electrical conductivity of nickel is relatively close to that of stainless steel at low temperature, the magnetic permeability of nickel is much higher than that of stainless steel. Therefore, in the induction heating, hysteresis loss generated by the nickel-plated stainless steel sheet induction heating eddy current is larger than that of the stainless steel sheet surface, resulting in that nickel is more easily heated, thereby accelerating the release of gas molecules adsorbed by the adsorbent 601. Meanwhile, the temperature of the stainless steel plate layer 603 is kept at a relatively low level, so that the overall temperature is prevented from being too high, and the cooling requirement of the low-temperature cold plate 6 before the subsequent use of the low-temperature pump for exhausting again is greatly reduced. The principle by which the adsorbent 601 can capture gas is that the temperature of the cryopanel 6 is below the condensation temperature of the deuterium tritium gas, and the gas is condensed or adsorbed on the cryopanel 6 in the cryopump.

A plurality of temperature sensors are arranged in the cryopump, the temperatures at different positions in the cryopump are monitored respectively, then temperature signals are generated, the temperature signals are transmitted to a system controller connected with the temperature sensors, insulating ceramics are arranged between sensitive units of the temperature sensors and a structure to be measured, and in addition, the temperature sensors have shielding functions and are calibrated, so that the anti-interference capacity and the accuracy of the temperature sensors are improved. After receiving the temperature signal, the system controller processes and analyzes the temperature signal, makes a decision according to a preset control strategy and a multi-source information fusion algorithm, generates a corresponding control signal, and sends the corresponding control signal to an adjustable radio frequency power supply to adjust the output power, frequency and working mode of the radio frequency power supply. The induction heating frequency needs to be adjusted according to the requirements of heating depth and speed, the surface is heated preferentially by high frequency, the uniformity of internal heating is facilitated by low frequency, the accurate control of induction heat on the low-temperature cold plate 6 is realized by adjusting the output power, frequency and working mode of a radio frequency power supply, the temperature at different positions is ensured to reach preset requirements, and the uniformity of heating is realized. The temperature sensor for monitoring the cryocooler 6 and the induction coil 5 has the characteristics of high response rate and low response time.

Specifically, as shown in fig. 1, an adjustable radio frequency source is electrically connected to the induction coil 5, and the adjustable radio frequency source supplies current to the induction coil 5 to cause the induction coil 5 to generate a magnetic field, and the generated magnetic field acts on the cryocooler 6 to cause the cryocooler 6 to be heated. By adjusting the power and output power, frequency of the adjustable radio frequency source, the magnitude of the inductive heat that the induction coil 5 acts on the cryocooler 6 can be adjusted. The induction coil 5 is a low-temperature cold plate 6 radio frequency induction heating unit.

It should be noted that, when the induction coil 5 is selected, the heating parameters of the induction coil 5 need to be reasonably selected to control the skin effect, so as to ensure the uniformity and stability of the heating effect. This can be achieved by adjusting the induction heating frequency, coil design, and conductor materials, among other ways. For induction heating of a circumferentially array of elongated cold plates 6 at low temperature, the coil structure should be chosen to be long and narrow, capable of closely or approximately matching the shape of the object to be heated, to achieve uniform and efficient heating. The selection of the number of turns of the coil is also very critical, and the more the number of turns is, the stronger the magnetic field generated by induction is, and the better the heating effect is. However, it is also considered that an increase in the number of turns of the coil causes an increase in the size of the coil, possibly affecting the installation space. The induction heating frequency needs to be adjusted according to the heating depth and the heating speed, the surface is heated preferentially by the high frequency, and the uniformity of internal heating is facilitated by the low frequency. The conductor material of the coil will typically be chosen to have a high electrical conductivity and a low magnetic permeability, such as copper. This can improve energy efficiency and heating effect.

An exhaust port 10 is arranged on the pump shell 2 of the cryopump and opposite to the second end of the valve 1, and the exhaust port 10 is connected with a mechanical pump. Deuterium tritium fuel and helium ash desorbed in the cryopump are filled in the cryopump, and the mechanical pump pumps the deuterium tritium fuel and helium ash out of the cryopump through the exhaust port 10.

As shown in fig. 3, the stainless steel plate layer 603 of the cryogenic cold plate 6 is internally provided with a first cooling channel 604, and after the mechanical pump pumps out the deuterium-tritium fuel and helium ash in the cryogenic pump, the temperature of the cryogenic cold plate 6 needs to be reduced again below the condensation temperature of the deuterium-tritium gas. The first cooling channel 604 can provide rapid cooling after induction heating regeneration, so that the cryogenically cooled panel 6 can be quickly restored to a low temperature state. The liquid helium is introduced into the first cooling channel 604 to reduce the temperature of the cryogenic cold plate 6, so that the cryogenic pump regains the pumping capability, and in addition, the cryogenic pump can maintain the temperature of the cryogenic cold plate 6 by introducing the first cooling medium into the first cooling channel 604 during pumping. The mechanical pump is connected with a system controller, and the system controller controls the opening and closing of the mechanical pump and controls the pumping speed of the mechanical pump. Temperature sensors are arranged on the low-temperature cold plate 6 and the induction coil 5 and are used for monitoring the temperatures of the low-temperature cold plate 6 and the induction coil 5 respectively.

In summary, the low-temperature pump rapid regeneration system and the method suitable for the steady-state operation of the tokamak are applied to a tokamak device, and comprise a low-temperature pump, a mechanical pump, a mass spectrometer, an adjustable radio frequency source and a system controller; the low-temperature pump is connected with the vacuum chamber of the tokamak device and is used for condensing gas in the vacuum chamber and adsorbing reaction products so as to ensure the vacuum degree of the vacuum chamber; the mass spectrometer is connected between the cryogenic pump and the system controller and is used for monitoring the gas content in the cryogenic pump so as to judge the air extraction effect and the regeneration process of the cryogenic pump; the low-temperature pump comprises a pump shell and low-temperature cold plates distributed in a circumferential array in the pump shell, a valve is arranged at the first end of the pump shell, and the system controller is used for controlling the opening and closing of the valve according to the air extraction effect and the regeneration process so as to control the inflow of the air; the low-temperature cold plate comprises a stainless steel plate layer with a nickel layer plated on one side, wherein an adsorbent is arranged on the outer side of the nickel layer and is used for adsorbing the gas and the reaction product to the surface of the adsorbent;

The cryopump further comprises at least one temperature sensor, wherein the temperature sensor is used for monitoring the temperature of at least one structure in the cryopump and generating a temperature signal; the temperature sensor is connected with the system controller and transmits the temperature signal to the system controller; the system controller is connected with the adjustable radio frequency source, and is used for judging the temperature signal and controlling and adjusting the working parameters of the adjustable radio frequency source according to the judging result; the adjustable radio frequency source is also electrically connected with an induction coil which is spirally connected with the periphery of the low-temperature cold plate; the adjustable radio frequency source is used for providing current to the induction coil so that the induction coil generates a magnetic field; the magnetic field acts on the low-temperature cold plate to enable the low-temperature cold plate to generate induced current to increase the temperature, so that the gas adsorbed on the low-temperature cold plate is desorbed; the second end of the pump shell is also provided with an exhaust port, and the mechanical pump is communicated with the interior of the cryopump through the exhaust port; the mechanical pump is used for pumping the desorbed gas in the cryopump through the vent after the cryopump is regenerated; the low-temperature pump regeneration system heats the low-temperature cold plate through induction heating and utilizes the skin effect of induction current to realize the rapid temperature rise of the surface layer of the low-temperature cold plate, thereby enabling the low-temperature pump to regenerate rapidly. In addition, according to the temperature signal transmitted by the temperature sensor, the temperature of the low temperature Leng Ban can be accurately controlled during desorption of the low temperature pump by adjusting the working parameters of the adjustable radio frequency source.

In one possible embodiment, the cryopump further includes a push assembly, a cold shield, and a radiation shield;

Specifically, as shown in fig. 2, the cold shield 3 in the cryopump is located between the pump housing 2 and the induction coil 5, because overheating of the induction coil 5 may reduce heating efficiency when the induction coil 5 generates a magnetic field. The cold screen 3 is thus arranged close to the induction coil 5 and can carry away part of the joule heat. In addition, when the cryopump is pumping, the internal low temperature needs to be kept, and the cold shield 3 is arranged in the pump shell 2, so that heat radiation outside the pump shell 2 can be isolated, and the influence of the external heat radiation on the low temperature inside the cryopump is prevented. Temperature sensors are also provided on the cold screen 3 and the radiation shield 7 to monitor the temperature of the cold screen 3 and the radiation shield 7. The system controller compares the real-time data transmitted by the temperature sensor with a preset safe temperature range to check whether the system is in a normal operation state at the stage. If a temperature outside a predetermined range is detected, the controller may adjust the operating parameters to prevent overheating of the system. A temperature sensor with radiation resistance is also arranged between the pump shell 2 and the cold shield 3, and the temperature between the pump shell 2 and the cold shield 3 is monitored.

The gas in the vacuum chamber enters the fluid channel in the cryopump through the valve 1, and the radiation baffle 7 is in the shape of a circular truncated cone annulus and is stacked inside the cryopanel 6 with a certain interval to form a cylindrical channel, which is arranged between the cryopanel 6 and the cylindrical channel, and precools the gas entering the cryopump from the vacuum pump.

The valve 1, the pushing component 8 and the air cylinder component 11 are connected together in a coaxial installation and matching mode, the pushing component 8 is connected with a system controller, and the system controller controls the opening and closing of the valve 1 through controlling the pushing component 8 and the air cylinder component 11.

In one possible embodiment, the cryopump further comprises a coil clamping structure for fixing the induction coil;

Specifically, fig. 4 is a schematic diagram of a coil clamping structure according to an embodiment of the present invention.

As shown in fig. 4, the induction coil 5 is clamped between the base 404 and the clamp 401, and fastened by the first bolt assembly 402, so as to fix the induction coil 5, and the coil clamping structure 4 is used for fixing the induction coil 5, and ensuring that the relative positions of the induction coil 5 and the cryocooler 6 are not changed, thereby playing a stable supporting and positioning role. The first insulating ceramic cylinder 403 is arranged between the base 404 and the clamp 401, and the base 404 and the clamp 401 are electrically isolated from the induction coil 5 while the induction coil 5 is clamped by the first insulating ceramic cylinder 403, so that the stability and the safety of the system are ensured.

In one possible implementation manner, a pressure sensor and a pressure relief valve arranged at the second end of the pump shell are further arranged in the cryogenic pump, and the pressure relief valve is communicated with the interior of the cryogenic pump through a pressure relief valve interface arranged at the second end of the pump shell;

Specifically, as shown in fig. 1, a high-precision pressure transmitter is employed for a pressure sensor provided in the cryopump. The pressure transmitter dynamically monitors the pressure in the cryopump and transmits the acquired pressure signal to the system controller. In addition, the pressure sensor also has the characteristic of temperature compensation, and is prevented from inaccurate measurement caused by overhigh or overlow temperature. A gap is arranged between a sensitive unit of the pressure sensor and the induction coil, and the pressure sensor has a shielding function and is calibrated so as to improve the anti-interference capability and the accuracy.

The pressure relief valve at the second end of the pump shell 2 is connected with the cryopump through a pressure relief valve interface 12 on the pump shell 2, and overpressure protection is provided for the whole operation stage of the cryopump. The system controller evaluates the operating state of the system based on the real-time pressure signal and a predetermined pressure criterion. If the pressure is too high or too low, the controller will change the pressure to the normal range by adjusting the state of the fluid valve 1 in the system or by adjusting the pumping speed of the mechanical pump. Mainly in the induction heating fast regeneration stage, prevent that gas regeneration from causing the damage to the subassembly in the cryopump too soon. When the pressure value in the cryopump exceeds a safety value which is preset in the system and can be born by the cryopump due to the fact that the regeneration speed is too high, the system controller controls the pressure relief valve to be opened.

In one possible embodiment, the induction coil further comprises an impedance matching unit connected between the induction coil and the adjustable radio frequency source, wherein the impedance matching unit is used for matching the impedance of the induction coil and the adjustable radio frequency source so as to maximize the energy transmitted by the adjustable radio frequency source to the induction coil.

As shown in fig. 1, the impedance matching unit connected between the induction coil 5 and the adjustable radio frequency source matches the impedance of the induction coil 5 and the adjustable radio frequency source, so that the efficiency of energy transmission from the adjustable radio frequency source to the induction coil 5 is maximized.

In one possible embodiment, the cryopump further includes an electrode flange disposed at a second end of the pump housing;

Specifically, when the induction coil 5 generates a magnetic field to generate induction heat on the low-temperature cold plate 6, the induction coil 5 causes a rise in resistivity of the coil due to a rise in temperature by passing a current, resulting in weakening of the induction magnetic field and a reduction in heating efficiency. The second cooling channel is arranged inside the induction coil 5, so that the system controller can maintain the dynamic balance of induction heating current through water circulation, and the joule heat of the induction coil 5 can be reduced.

Fig. 5 is a schematic structural diagram of an electrode flange according to an embodiment of the present application.

As shown in fig. 5, the induction coil 5 is led out from the inside of the cryopump to the second end of the pump casing 2 and passes through the electrode flange 9, a coil lead-out section for circulating water with the external water chiller is left on one side of the electrode flange 9, and an electrode flange cover 902 of the electrode flange 9 is fixed to the pump casing 2 by a second bolt assembly 901. The second cooling medium circulates between the second channel inside the induction coil 5 and the external water chiller through the cooling loop interface 501 of the coil lead-out section port. In the present application, water is used as the second medium. In addition, an electrode interface 502 on the electrode flange 9 is connected with the lead-out section, current generated by an adjustable radio frequency source is led into the induction coil 5, and a second insulating ceramic cylinder 903 is arranged at the contact part of the electrode flange 9 and the coil lead-out section.

In order to more clearly describe the cryopump regeneration system provided by the embodiment of the present invention, a method for processing the system is described in detail below with reference to fig. 6.

As shown in fig. 6, the regeneration method includes the steps of:

and step 101, after the low Wen Bengfa door is controlled to be opened, under the condition that a vacuum chamber and a channel of an air extraction system are opened, acquiring the first gas content in the cryopump acquired by the mass spectrometer.

Specifically, the system controller controls the valve 1 of the cryopump to be opened, that is, the vacuum chamber and the air extraction system are in a communication state, and the air in the vacuum chamber can enter the cryopump through the valve 1, and the cryopump is in an air extraction state at the moment. And in the state of the low-temperature pump, the mass spectrometer monitors the content of the first gas in the low-temperature pump in real time, and synchronizes the monitoring result to the system controller.

Step 102, determining whether the first gas content reaches a preset value; the preset value is stored in a control program of the system controller.

Specifically, the allowable value of the tokamak device refers to the maximum value of the allowable deuterium-tritium gas content in the vacuum chamber capable of enabling the tokamak device to normally operate, and in the present invention, the preset value is set to eighty percent of the maximum value. The system controller receives the first gas content and compares the specific value of the first gas content with a preset value stored in a control program of the system controller. .

And step 103, when the first gas content reaches the preset value, controlling the valve to be closed.

Specifically, the system controller compares the received value of the first gas content with a preset value, when the value of the first gas content is the same as the preset value, which indicates that the pumping capacity of the current cryopump is saturated, and the system controller closes the valve 1 of the current cryopump by controlling the pushing component 8 and simultaneously opens another group of cryopumps to operate so as to pump the vacuum chamber.

In step 104, the adjustable rf source is controlled to be turned on so that the magnetic field generated by the induction coil causes the low temperature Leng Ban to generate an induced current to raise the temperature.

Specifically, after the valve 1 of the current cryopump is closed, the gas adsorbed in the current cryopump is desorbed. The system controller controls the adjustable radio frequency source to be turned on, and provides current for the induction coil 5, so that the induction coil 5 generates a magnetic field, and the magnetic field acts on the cryogenic cold plate 6 to enable the cryogenic cold plate 6 to generate current so as to increase the temperature. When the temperature of the cryopanel 6 exceeds the gas condensation or adsorption temperature, the gas condensed or adsorbed on the cryopanel 6 gradually desorbs and fills the cryopump.

And 105, controlling the mechanical pump to be started so as to pump the gas to the low-temperature pump, and discharging the gas generated in the low-temperature pump.

Specifically, after the system controller controls the cryogenic pump to enter the desorption stage, the mechanical pump is started, so that the mechanical pump pumps the cryogenic pump, and the desorbed gas in the cryogenic pump is pumped out.

And 106, monitoring the temperature of the low-temperature cold plate through a temperature sensor, and adjusting the parameters of the adjustable radio frequency source according to the monitoring result.

Specifically, after the desorption stage is entered, the temperature of the cryocooler 6 is monitored by a temperature sensor disposed at the cryocooler 6, and when the temperature does not reach the temperature preset in the control program, the parameters of the adjustable radio frequency source are adjusted to ensure that the desorption stage is performed.

Step 107, obtaining a change condition of the second gas content in the cryopump in a preset first period from the mass spectrometer.

Specifically, when the mechanical pump pumps the cryogenic pump, the system controller obtains the content change condition of deuterium-tritium gas in the cryogenic pump in a first time period through the mass spectrometer. In the air extraction process, the content of deuterium-tritium gas in the cryopump is the second gas content.

And step 108, determining whether the low-temperature pump completes the desorption stage according to the change condition of the second gas content, and after determining that the desorption stage is completed, introducing a first cooling medium into the first cooling channel of the low-temperature cold plate so as to reduce the temperature of the low-temperature cold plate to a preset adsorption temperature, so that the low-temperature pump regains the pumping capacity.

Specifically, as the desorption stage proceeds, the content of the desorbed gas in the cryopump becomes smaller, and the system controller determines whether the cryopump has completed desorption according to the acquired change of the second gas content in the first period. When the system controller determines that the desorption phase is completed, a certain residual temperature is left on the cryocooler 6, and the system controller rapidly reduces the temperature of the cryocooler 6 by introducing liquid helium into the first cooling channel 604 of the cryocooler 6.

In one possible implementation manner, the monitoring the temperature of the cryocooler and adjusting the parameter of the adjustable radio frequency source according to the monitoring result specifically includes:

Specifically, the system controller acquires a temperature signal monitored by a temperature sensor provided at the cryopanel 6, and compares a specific temperature value contained in the temperature signal with a target desorption temperature value of a gas preset in a control program. The target desorption temperature value is a temperature at which deuterium-tritium gas adsorbed on the cryogenic cold plate 6 can be desorbed smoothly.

After the system controller compares the obtained temperature value of the low-temperature cold plate 6 with the target desorption temperature value, when the temperature value of the low-temperature cold plate 6 is judged to be smaller than the target desorption temperature, the system controller adjusts the working parameters of the adjustable radio frequency source, namely, the output power is increased, and the induction current of the induction coil 5 acting on the low-temperature cold plate 6 is increased, so that the temperature of the low-temperature cold plate 6 is increased. When the system controller judges that the temperature value of the low-temperature cold plate 6 reaches the target desorption temperature, the adjustable radio frequency source is not adjusted.

In a possible embodiment, the determining whether the cryogenic pump completes the desorption stage according to the change condition of the second gas content specifically includes:

determining that a desorption phase of the cryopump is incomplete when the second gas content varies; when the second gas content is unchanged, determining that the desorption phase of the cryopump is complete.

Specifically, after acquiring the change condition of the second gas content in the low-temperature pump in the desorption stage from the mass spectrometer, the system controller judges whether the desorption stage is completed according to the change condition of the second gas content. While the desorption phase is incomplete, the deuterium-tritium gas content is gradually decreasing, that is to say the second gas content is changing, over a period of time. When the desorption stage is completed, the content of the second gas in the cryopump is almost 0, and after a period of time, the content of the second gas in the cryopump is still 0, and almost no change occurs.

In summary, the low-temperature pump rapid regeneration system and method suitable for tokamak steady-state operation provided by the embodiment of the invention are applied to tokamak devices, and comprise a low-temperature pump, a mechanical pump, a mass spectrometer, an adjustable radio frequency source and a system controller; the low-temperature pump is connected with the vacuum chamber of the tokamak device and is used for condensing gas in the vacuum chamber and adsorbing reaction products so as to ensure the vacuum degree of the vacuum chamber; the mass spectrometer is connected between the cryogenic pump and the system controller and is used for monitoring the gas content in the cryogenic pump so as to judge the air extraction effect and the regeneration process of the cryogenic pump; the low-temperature pump comprises a pump shell and low-temperature cold plates distributed in a circumferential array in the pump shell, a valve is arranged at the first end of the pump shell, and the system controller is used for controlling the opening and closing of the valve according to the air extraction effect and the regeneration process so as to control the inflow of the air; the low-temperature cold plate comprises a stainless steel plate layer with a nickel layer plated on one side, wherein an adsorbent is arranged on the outer side of the nickel layer and is used for adsorbing the gas and the reaction product to the surface of the adsorbent;

The cryopump further comprises at least one temperature sensor, wherein the temperature sensor is used for monitoring the temperature of at least one structure in the cryopump and generating a temperature signal; the temperature sensor is connected with the system controller and transmits the temperature signal to the system controller; the system controller is connected with the adjustable radio frequency source, and is used for judging the temperature signal and controlling and adjusting the working parameters of the adjustable radio frequency source according to the judging result; the adjustable radio frequency source is also electrically connected with an induction coil which is spirally connected with the periphery of the low-temperature cold plate; the adjustable radio frequency source is used for providing current to the induction coil so that the induction coil generates a magnetic field; the magnetic field acts on the cryogenic cold plate to raise the temperature of the cryogenic cold plate, thereby desorbing the gas adsorbed on the cryogenic cold plate; the second end of the pump shell is also provided with an exhaust port, and the mechanical pump is communicated with the interior of the cryopump through the exhaust port; the mechanical pump is used for pumping the desorbed gas in the cryopump through the vent after the cryopump is regenerated; the low-temperature pump regeneration system heats the low-temperature cold plate through induction heating and utilizes the skin effect of induction current to realize the rapid temperature rise of the surface layer of the low-temperature cold plate, thereby enabling the low-temperature pump to regenerate rapidly. In addition, according to the temperature signal transmitted by the temperature sensor, the temperature of the low temperature Leng Ban can be accurately controlled during desorption of the low temperature pump by adjusting the working parameters of the adjustable radio frequency source.

It should be noted that, after the system controller obtains the distributed temperature information and the integral pressure information, the system controller processes and analyzes the temperature data and the pressure data, and adjusts the adjustable radio frequency source according to the analysis processing result. These data come from the various critical parts of the system, which must be analyzed and processed synthetically to ensure system stability and effectiveness. The system controller includes a data processing unit that integrates all the received sensor data and uses advanced algorithms to resolve to determine the current state of the system and the degree of completion of the stage in which the system is located. For temperature data, the controller compares the real-time data with a predetermined safe temperature range to check whether the system is in a normal operation state at this stage. If a temperature outside a predetermined range is detected, the controller may adjust the operating parameters to prevent overheating of the system. For pressure data, the controller will evaluate the operating state of the system based on the real-time pressure data and predetermined pressure criteria. If the pressure is too high or too low, the controller will change the pressure to the normal range by adjusting the fluid valve opening state in the system or adjusting the mechanical pumping speed.

After the analysis, when the system detects a deviation from normal operating conditions, the controller will make a reverse adjustment to correct the deviation. Specifically, the controller may achieve the desired temperature and pressure conditions of the stage system by varying the frequency, power, or other adjustable parameters of the adjustable radio frequency source. The whole control process is real-time and continuous, ensures the stable operation of the system, and can respond quickly to sudden temperature or pressure changes. The intelligent control system greatly enhances the reliability and efficiency of the system and provides possibility for realizing higher performance standard.

Fig. 7 is a graph comparing a low temperature Leng Ban heating curve of a nickel-plated stainless steel plate layer with a low temperature Leng Ban heating curve of stainless steel based on an induction heating method according to an embodiment of the present invention.

As shown in fig. 7, the abscissa represents time in min, and the ordinate represents temperature in K, and the temperature rise rate of the method can be compared with that of the conventional method by the simulation means. The upper curve in fig. 7 is a 316L stainless steel sheet with a nickel coating, the lower curve is a conventional 316L stainless steel sheet without a nickel coating, and the low temperature Leng Ban applied in a commercial cryopump is a 316L stainless steel sheet without a nickel coating. Under the premise of adopting induction heating, the heating rate of the stainless steel plate layer with the nickel coating 316L is higher than that of a stainless steel plate without the nickel coating in the same time, that is, the method can realize remarkably rapid heating compared with a commercial cryopump which needs regeneration for a plurality of hours under the same temperature change range. This rapid temperature rise helps to improve production efficiency and reduces energy consumption during heating. The rapid temperature rise is helpful for guaranteeing steady-state operation of plasma discharge of the Tokamak vacuum chamber and reducing the number of low-temperature pump sets of the air extraction system.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims

1. The low-temperature pump rapid regeneration system suitable for the steady-state operation of the tokamak is characterized by being applied to a tokamak device and comprising a low-temperature pump, a mechanical pump, a mass spectrometer, an adjustable radio frequency source and a system controller;

2. The system of claim 1, wherein the cryopump further comprises a push assembly, a cold shield, and a radiation shield;

3. The system of claim 1, wherein the cryopump further comprises a coil clamping structure for securing the induction coil;

4. The system of claim 1, wherein a pressure sensor and a relief valve disposed at the second end of the pump housing are further disposed in the cryopump, the relief valve being in communication with the interior of the cryopump through a relief valve interface disposed at the second end of the pump housing;

the pressure sensor is connected with the system controller and is used for monitoring a pressure signal in the system and transmitting the pressure signal to the system controller;

5. The system of claim 1, further comprising an impedance matching unit connected between the induction coil and the adjustable radio frequency source, the impedance matching unit for matching impedances of the induction coil and the adjustable radio frequency source to maximize energy transferred by the adjustable radio frequency source to the induction coil.

6. The system of claim 1, wherein the cryopump further comprises an electrode flange disposed at a second end of the pump housing;

7. A method of rapid regeneration of a cryopump adapted for steady state operation of tokamak, applied to the system of any one of claims 1-6, the method comprising:

8. The method of claim 7, wherein the monitoring the temperature of the cryogenically cooled panels and adjusting the parameters of the adjustable rf source based on the monitoring result comprises:

9. The method of claim 7, wherein said determining whether the cryopump has completed a desorption phase based on a change in the second gas content, in particular, comprises: