High-frequency cavity accelerated exercise method for searching for limit value lower than starting pulse

Abstract

The invention provides a high-frequency cavity accelerated exercise method for searching a limit value lower than a starting pulse. The high-frequency cavity accelerated exercise method comprises the following steps: completing a high-frequency cavity preliminary exercise mode; setting a high-frequency starting pulse K0, and entering a high-frequency starting mode; if the high-frequency starting fails, entering an accelerated exercise mode; in the accelerated exercise mode, the K0 continues to be used for conducting preliminary exercise of the high-frequency cavity, when the preliminary exercise reaches the amplitude-phase stable stage, searching and exercise of a high-frequency starting pulse limit value KA lower than the high-frequency starting pulse K0 are conducted till the KA pulse of the limit value can enable the high-frequency cavity to be normally started, and the high-frequency cavity accelerated exercise mode is completed; and for the high-frequency cavity completing accelerated exercise, the high-frequency cavity is successfully started at one time by using a pulse K0 higher than a limit value KA. According to the method, high-frequency starting succeeds at a time through a limit value searching method, and compared with a preliminary exercise method that starting succeeds only through repeated exercise, the efficiency of high-frequency cavity exercise is effectively improved, and the time of high-frequency exercise is saved exponentially.

Description

Technical Field

[0001] The invention belongs to the technical field of cyclotron high-frequency systems, and in particular relates to a high-frequency cavity acceleration training method for finding a limit value lower than a starting pulse. Background Art

[0002] The high-frequency system is one of the important parts of the cyclotron, and its stability and reliability play a key role in the performance of the cyclotron. The high-frequency system of the cyclotron mainly consists of three parts: high-frequency power source, resonant cavity and low-level system. The high-frequency power source is responsible for providing energy for the movement of particles; the resonant cavity can provide a stable high-frequency electric field for charged particles through resonance; the low-level system is to control and correct the amplitude, phase and other parameters of the acceleration field to ensure the stable operation of the cavity.

[0003] During the operation of the accelerator high-frequency system, difficult starting and sparking during power ramping are important factors affecting high-frequency stability: the difficult starting refers to the fact that during the high-frequency starting stage, the signal fed into the resonant cavity by the transmitter is almost completely reflected due to the secondary electron multiplication effect, which is called difficult starting; the high-frequency sparking refers to the arc discharge phenomenon that occurs when high-frequency is fed in. Its characteristics are: first, the acceleration gap in the central area is smaller than the acceleration gap in the outer radius. Under high-voltage conditions, this part is very easy to be broken down and sparked; certain burrs on the cavity surface can also cause sparking. Second, during the power ramping stage from low power to high power, the higher the power fed in and the faster the power increases, the more likely sparking will occur, and the power fed in drops sharply at the moment of sparking.

[0004] At present, the operation that can overcome the above-mentioned difficult start and climbing ignition is high-frequency training: overcoming the electron multiplication effect and high-power ignition by feeding high-frequency signals for a long time. Disadvantages: First, it takes a long time. A small cyclotron accelerator takes two weeks, and a high-energy cyclotron generally takes a month or even longer; second, it is inefficient and has poor actual effects. The low efficiency and poor actual effects refer to whether the initial training is currently performed using a signal source or a low-level control signal. When the machine is turned off and then turned on again, even if the interval time is only a few minutes or even seconds, there is still a high probability that it cannot be started. The reason for the failure to start is that the restart pulse should be higher than the pulse in the initial training stage to start successfully, but starting with a pulse higher than the initial training stage will cause the transmitter to trip, because the starting pulse during the initial training is already a capped pulse. Therefore, for the safety of the equipment, when it is restarted after a few minutes of shutdown, the starting pulse during the initial training can only be used. This leads to a high probability that it still cannot start successfully when it is restarted after a few minutes or even seconds of shutdown. This is the so-called low efficiency and poor actual effect in the initial training stage. Summary of the invention

[0005] In order to solve the problems existing in the prior art, the present invention proposes a high-frequency cavity acceleration training method for finding a limit value below the starting pulse, aiming to solve the problems of low efficiency and poor practical effect of the existing high-frequency cavity initial training.

[0006] The present invention proposes the following technical solutions to solve the technical problems:

[0007] A high-frequency cavity acceleration training method for finding a pulse below the starting pulse limit value is characterized by comprising the following steps:

[0008] Step 1: Complete the preliminary training mode of the high-frequency cavity;

[0009] Step 2: Set the high-frequency start pulse K0 and enter the high-frequency start mode;

[0010] Step 3: If high-frequency activation fails, enter the accelerated training mode;

[0011] In the acceleration training mode, the high-frequency start pulse limit value KA lower than the high-frequency start pulse K0 is searched and trained until the KA pulse of the limit value can enable the high-frequency cavity to start normally. At this time, the high-frequency cavity acceleration training mode is completed;

[0012] Step 4: For the high-frequency cavity that has completed the acceleration training, the high-frequency cavity is successfully started once with a high-frequency starting pulse K0 higher than the limit value KA.

[0013] Furthermore, the algorithm flow of the accelerated training mode in step 3 is as follows:

[0014] 1) Set the initial value of the start pulse amplitude word KI in the D1 state to the maximum start pulse amplitude word K0;

[0015] 2) Accelerate the training mode to enter the D0 state, that is, the initial state: after receiving the power-on command, check whether the system interlocking protection is normal. If normal, migrate to the D1 state, otherwise maintain D0;

[0016] 3) The acceleration training mode enters the D1 state, that is, the pulse search mode; the tuning loop controls the tuning motor to search for frequency, and uses the current starting pulse amplitude word KI for high-frequency feed; after the pulse turns continuous, the state is pushed to D2.

[0017] 4) Accelerate the training mode to enter the D2 state; that is, the amplitude ramping stage to increase the RF power, the ramping is faster when the power is low, and the ramping is slower when the power is high; in this process, the tuning control board continues to work, and after the amplitude loop is closed, the power increase is stopped, and the state is pushed to D3;

[0018] 5) The acceleration training mode enters the D3 state, which is the phase matching stage. The phase detector output and algorithm in the phase control board are used to achieve phase matching. After achieving phase matching, the state reaches the D4 state;

[0019] 6) The acceleration training mode enters the D4 state. In the D4 state, the high-frequency starting pulse limit value KA that is lower than the high-frequency starting pulse K0 is searched and trained until the KA pulse of the limit value can enable the high-frequency cavity to start normally. At this time, the high-frequency cavity acceleration training mode is completed, that is, the amplitude-phase closed-loop stage.

[0020] Furthermore, the process 6) of step 3 is to search and train the high-frequency starting pulse limit value KA which is lower than the high-frequency starting pulse K0, and the specific steps are as follows:

[0021] A) Enter the D4 phase amplitude and phase stabilization phase under the acceleration training mode, and automatically switch back to the D0 phase under the acceleration training mode after 5 minutes of stabilization, and then enter the D1 pulse start phase under the acceleration training mode from the D0 phase;

[0022] B) In the D1 state of the acceleration training mode, the pulse starts the current amplitude word KI down to a set value, and uses this set value to restart the high-frequency cavity in the acceleration training mode. After the start is successful, return to the process 3 of step three) and enter the D1 state;

[0023] Furthermore, the step B) of the process 6) of step 3 until the falling starting pulse value reaches the starting pulse limit value KA is as follows:

[0024] 1) The judgment condition is 5 minutes, and the high-frequency cavity does not rise within 5 minutes;

[0025] 2) The starting pulse value of step 3 of process 3) is cut to the last value that can be started, which is the limit value KA.

[0026] Advantages and effects of the present invention

[0027] 1. The present invention achieves one-time success in high-frequency start-up by finding the limit value. Compared with the initial training method in the prior art which requires repeated training to successfully start, the efficiency of high-frequency cavity training is effectively improved, and the time of high-frequency training is saved exponentially.

[0028] 2. The present invention is designed to increase the power ramp speed more and more slowly as the power increases, thereby reducing the increase in the number of ignition times caused by the rapid increase in power and improving the stability of the high frequency during startup. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A flow chart of the high frequency cavity acceleration training method for finding a value below the starting pulse limit value of the present invention;

[0030] Figure 2 This is a structural diagram of the high-frequency cavity acceleration training device for the present invention that is lower than the starting pulse limit value. DETAILED DESCRIPTION

[0031] Design principle of the present invention

[0032] 1. Innovation of the present invention: The innovation lies in finding a limit value pulse lower than the starting pulse. Since the limit value starting pulse is found in the acceleration training stage, and the high-frequency cavity is trained with the limit value starting pulse, the high-frequency cavity is adapted to start under the limit value pulse. After the acceleration training is completed, the high-frequency cavity is started with a pulse higher than the limit value KA and less than or equal to the peak value, so that the high-frequency start is 100% successful.

[0033] 2. Several key points of the present invention: First, the present invention solves the problem that after the high-frequency cavity completes the preliminary training, even if it is shut down for only a few minutes, it still fails to start again. The characteristic of this stage is that the high-frequency cavity has completed the preliminary training. Although it has been shut down for a few minutes, the adaptability of the high-frequency cavity has been attenuated very little within a few minutes. When the initial training is continued with the starting pulse K0, it can quickly enter the amplitude and phase stability stage; Second, the difference between the accelerated training mode of the present invention and the conventional preliminary training mode is that the starting pulse of the accelerated training mode is gradually reduced during the training process until it can no longer be started. In this process, the high-frequency cavity adapts to being able to start under the limit value pulse; while the initial training mode of the conventional method is that the starting pulse is unchanged during the training process and the starting pulse is capped. The starting pulse is unchanged, for example, the amplitude word 16000 is always used as the starting pulse. The starting pulse is capped, that is, the pulse cannot be higher, otherwise the transmitter will trip. The reason why the prior art uses the capped pulse as the starting pulse is that the higher the pulse, the easier it is for the cavity to start, so the conventional method uses the maximum pulse or the capped pulse as the starting pulse. Third, the accelerated training mode adopted by the present invention is compared with the preliminary training mode adopted by the prior art. After actual application, the high-frequency cavity training time can be saved by at least one-half, because the present invention first finds the limit value pulse, and then starts the high-frequency cavity with a pulse higher than the limit value and less than or equal to the peak value, so it can be successfully started at one time, while the success rate of the first high-frequency start after the preliminary training of the prior art is very low, because the starting pulse during the preliminary training is already a peak pulse. In this case, the starting pulse can only be equal to the pulse during the preliminary training (if it is higher than the pulse during the preliminary training, the transmitter will trip). Since the starting pulse cannot be higher than the pulse during the training, the success rate of the start is very small. In the case where the starting pulse cannot be higher than the pulse during the training, repeated training is required to achieve a 100% success rate. The 16MeV cyclotron of the Institute of Atomic Energy took 3 days to find the limit value and achieve 100% startup when using the present invention; according to experience and records, it took at least 6 days without using this method before, and it took twice as long to achieve this effect. Therefore, the training method of finding the limit value of the present invention is a method of accelerated training.

[0034] Based on the above invention principle, the present invention designs a high-frequency cavity acceleration training method for finding a limit value below the starting pulse. Figure 1 As shown, the method is based on a high-frequency cavity acceleration training device that is lower than the starting pulse limit value. Figure 2As shown, it includes a transmitter, a resonant cavity, a low-level control system, a directional coupler and a host computer; the transmitter is used to amplify the signal and feed it into the resonant cavity through a transmission line; its input end is connected to the low-level control system, and its output end is connected to the resonant cavity; the resonant cavity provides a stable high-frequency electric field for charged particles through resonance, and its input end is respectively connected to the transmitter and the low-level control system; the low-level control system controls the resonant capacitance of the resonant cavity through a motor; the directional coupler is arranged on the transmission line between the transmitter and the resonant cavity, and one of its functions is to obtain the reflected power signal from the resonant cavity, sample the reflected signal and transmit it to the low-level control system to complete reflection protection; its other function is to obtain the reflected power signal from the resonant cavity, sample the reflected signal and transmit it to the low-level control system to complete reflection protection; The incident power signal from the transmitter is sampled and used as one of the signals of the tuning loop. The other signal of the tuning loop comes from the sampling of the resonant cavity. The two signals are phase-detected and control the tuning motor to tune the resonant cavity frequency. The input end of the low-level control system is respectively connected to the resonant cavity and the directional coupler, and the internal power signal is obtained from the resonant cavity, and the incident power signal and the reflected power signal are obtained from the directional coupler. The host computer is bidirectionally connected to the low-level control system. The host computer switches the high-frequency start-up mode and the acceleration training mode by communicating with the low level. The two modes perform state migration in the low-level finite state machine and transmit the output signal to the transmitter.

[0035] The method is characterized in that it comprises the following steps:

[0036] Step 1: Complete the preliminary training mode of the high-frequency cavity;

[0037] Supplementary Note 1:

[0038] After purchasing a high-frequency cavity from a third party, it must undergo preliminary training before it can be used. The preliminary training is to continuously feed low power into the high-frequency cavity. After a certain period of time, the secondary electron multiplication effect of the high-frequency cavity can be overcome, so that the low power can eventually be fed into the high-frequency cavity.

[0039] Step 2: Set the high-frequency start pulse K0 and enter the high-frequency start mode;

[0040] Step 3: If high-frequency activation fails, enter the accelerated training mode;

[0041] Supplementary Note 2:

[0042] The high-frequency startup failure here refers to the high-frequency startup failure after the initial training. The reason for the failure is that the startup pulse cannot be higher than the initial training pulse. Only when the startup pulse is higher than the initial training pulse can the startup be successful. Since the pulse during the initial training is already a peak pulse, the high-frequency startup pulse after the initial training can only be equal to the peak pulse and cannot be greater than the peak pulse. If it is greater than the peak pulse, the transmitter will trip.

[0043] In the acceleration training mode, the high-frequency start pulse limit value KA lower than the high-frequency start pulse K0 is searched and trained until the KA pulse of the limit value can enable the high-frequency cavity to start normally. At this time, the high-frequency cavity acceleration training mode is completed;

[0044] Supplementary Note 3:

[0045] 1) Because K0 is already a capped pulse, when entering the accelerated training mode, the capped pulse K0 is still used to continue the initial training mode. When the amplitude and phase are stable, the limit value is searched.

[0046] 2) The difference between the training process and the starting process is that the signal of the training process is continuous, while the duty cycle of the starting pulse is 1:10. Since the training process continuously feeds power, even if the power may not be fed in at the beginning, there will always be a time when the power is fed in continuously. This process is the training process.

[0047] 3) The process of finding the limit value is to use a 1:10 pulse signal. Each time the starting pulse is lowered, power cannot be fed in at first. However, after a long period of continuous feeding, the cavity adapts to the power and can be fed in. At this time, the current pulse can be used as the starting pulse. This cycle repeats until the current pulse is the limit value pulse. The limit value pulse cannot be fed in no matter how it is trained. At this time, the previous starting pulse is used as the limit value pulse.

[0048] Step 4: For the high-frequency cavity that has completed the acceleration training, the high-frequency cavity is successfully started once with a high-frequency starting pulse K0 higher than the limit value KA.

[0049] Furthermore, the algorithm flow of the accelerated training mode in step 3 is as follows:

[0050] 1) Set the initial value of the start pulse amplitude word KI in the D1 state to the maximum start pulse amplitude word K0;

[0051] 2) Accelerate the training mode to enter the D0 state, that is, the initial state: after receiving the power-on command, check whether the system interlocking protection is normal. If normal, migrate to the D1 state, otherwise maintain D0;

[0052] 3) The acceleration training mode enters the D1 state, that is, the pulse search mode; the tuning loop controls the tuning motor to search for frequency, and uses the current starting pulse amplitude word KI for high-frequency feed; after the pulse turns continuous, the state is pushed to D2.

[0053] 4) Accelerate the training mode to enter the D2 state; that is, the amplitude ramping stage to increase the RF power, the ramping is faster when the power is low, and the ramping is slower when the power is high; in this process, the tuning control board continues to work, and after the amplitude loop is closed, the power increase is stopped, and the state is pushed to D3;

[0054] 5) The acceleration training mode enters the D3 state, which is the phase matching stage. The phase detector output and algorithm in the phase control board are used to achieve phase matching. After achieving phase matching, the state reaches the D4 state;

[0055] 6) The acceleration training mode enters the D4 state. In the D4 state, the high-frequency starting pulse limit value KA that is lower than the high-frequency starting pulse K0 is searched and trained until the KA pulse of the limit value can enable the high-frequency cavity to start normally. At this time, the high-frequency cavity acceleration training mode is completed, that is, the amplitude-phase closed-loop stage.

[0056] Furthermore, the process 6) of step 3 is to search and train the high-frequency starting pulse limit value KA which is lower than the high-frequency starting pulse K0, and the specific steps are as follows:

[0057] A) Enter the D4 phase amplitude and phase stabilization phase under the acceleration training mode, and automatically switch back to the D0 phase under the acceleration training mode after 5 minutes of stabilization, and then enter the D1 pulse start phase under the acceleration training mode from the D0 phase;

[0058] B) In the D1 state of the acceleration training mode, the pulse starts the current amplitude word KI down to a set value, and uses this set value to restart the high-frequency cavity in the acceleration training mode. After the start is successful, return to the process of step three 3) to enter the D1 state;

[0059] Furthermore, the step B) of the process 6) of step 3 until the falling starting pulse value reaches the starting pulse limit value KA is as follows:

[0060] 1) The judgment condition is 5 minutes, and the high-frequency cavity does not rise within 5 minutes;

[0061] 2) The starting pulse value of step 3 of process 3) is cut to the last value that can be started, which is the limit value KA.

[0062] Embodiment 1

[0063] 1. Taking the 16MeV accelerator as an example, after one month of normal training and the completion of low-power 2kW feed, the initial training is completed. At this time, if you want to feed in high power, although the initial training is completed, even if the maximum available pulse is used (for example, the amplitude word 16000 is the maximum pulse), it cannot be started every time it is turned on, which is also called high-frequency start mode failure.

[0064] 2. At this time, switch back to the acceleration training mode of the present invention, still use the maximum pulse (for example, the amplitude word 16000 is the maximum pulse), it may not be able to start, but once the power is fed in (no one can guarantee how much time this takes, each accelerator is different), you can cycle to find the limit value pulse. After finding the limit value pulse, switch back to the high-frequency start mode, it will definitely start, with almost 100% probability. The time for this process of finding the limit value is t (the characteristics of each accelerator are different, it cannot be accurately said that it takes a few days). If you do not use this limit value method to perform ordinary training for the same length of t, and then start again, the probability may be 50% (each accelerator is different, but it will definitely not reach the effect of the limit value). If you want to reach 100%, it may take twice as long or even more.

[0065] It should be emphasized that the above specific embodiments are merely explanations of the present invention, and they are not limitations of the present invention. After reading this specification, those skilled in the art can make modifications to the above embodiments without any creative contribution as needed, but as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A high-frequency cavity acceleration training method for finding a limit value below the starting pulse, characterized in that: The following steps are involved: Step 1: Complete the preliminary training mode of the high-frequency cavity; Step 2: Set the high-frequency start pulse K0 and enter the high-frequency start mode; Step 3: If high-frequency activation fails, enter the accelerated training mode; In the acceleration training mode, the high-frequency start pulse limit value KA lower than the high-frequency start pulse K0 is searched and trained until the KA pulse of the limit value can enable the high-frequency cavity to start normally. At this time, the high-frequency cavity acceleration training mode is completed; Step 4: For the high-frequency cavity that has completed the acceleration training, the high-frequency cavity is successfully started once with a high-frequency starting pulse K0 higher than the limit value KA.

2. The high-frequency cavity acceleration training method for finding a limit value below the starting pulse according to claim 1, characterized in that: The algorithm flow of the accelerated training mode in step 3 is as follows: 1) Set the initial value of the start pulse amplitude word KI in the D1 state to the maximum start pulse amplitude word K0; 2) Accelerate the training mode to enter the D0 state, that is, the initial state: after receiving the power-on command, check whether the system interlocking protection is normal. If normal, migrate to the D1 state, otherwise maintain D0; 3) The acceleration training mode enters the D1 state, that is, the pulse search mode; the tuning loop controls the tuning motor to search for frequency, and uses the current starting pulse amplitude word KI for high-frequency feed; after the pulse turns continuous, the state is pushed to D2. 4) Accelerate the training mode to enter the D2 state; that is, the amplitude ramping stage to increase the RF power, the ramping is faster when the power is low, and the ramping is slower when the power is high; in this process, the tuning control board continues to work, and after the amplitude loop is closed, the power increase is stopped, and the state is pushed to D3; 5) The acceleration training mode enters the D3 state, which is the phase matching stage; the phase detector output and algorithm in the phase control board are used to achieve phase matching. After the phase matching is achieved, the state reaches the D4 state; 6) The acceleration training mode enters the D4 state. In the D4 state, the high-frequency starting pulse limit value KA that is lower than the high-frequency starting pulse K0 is searched and trained until the KA pulse of the limit value can enable the high-frequency cavity to start normally. At this time, the high-frequency cavity acceleration training mode is completed, that is, the amplitude-phase closed-loop stage.

3. The high-frequency cavity acceleration training method for finding a limit value below the starting pulse according to claim 1, characterized in that: The process 6) of step 3 is to search and train the high-frequency starting pulse limit value KA which is lower than the high-frequency starting pulse K0, and the specific steps are as follows: A) Enter the D4 phase amplitude and phase stabilization phase under the acceleration training mode, and automatically switch back to the D0 phase under the acceleration training mode after 5 minutes of stabilization, and then enter the D1 pulse start phase under the acceleration training mode from the D0 phase; B) In the D1 state of the acceleration training mode, the pulse starts the current amplitude word KI down to a set value, and uses this set value to restart the high-frequency cavity in the acceleration training mode. After the start is successful, return to step three process 3) to enter the D1 state.

4. The high-frequency cavity acceleration training method for finding a limit value below the starting pulse according to claim 3, characterized in that: The process of step 3 in step B) of process 6) is as follows: 1) The judgment condition is 5 minutes, and the high-frequency cavity does not rise within 5 minutes; 2) The starting pulse value of step 3 of process 3) is cut to the last value that can be started, which is the limit value KA.

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