High-frequency cavity ignition safety interlocking protection method and system

Abstract

The invention discloses a high-frequency cavity ignition safety interlocking protection method and system, and the method comprises the steps: 1), setting two FIFOs in a low-level control system, collecting the incident power, the reflection power and the cavity field power of a high-frequency cavity in real time, respectively storing the incident power, the reflection power and the cavity field power in the two FIFOs, enabling a signal stored in one FIFO to be a signal at the time T before the current moment, and enabling a signal stored in the other FIFO to be a signal at the time T before the current moment; the signal stored in the other FIFO is a signal in 2T time before the current moment; (2) the ignition event monitoring unit collects signals of the high-frequency cavity at the current moment and compares the signals with signals collected at the previous time T and 2T, and if the signals meet set conditions, ignition event triggering signals are generated; (3) when the ignition event interlocking processing unit receives the ignition event trigger signals for no more than N times in a set time period, the forward power excitation signal is temporarily cut off and then is quickly recovered; and the forward power excitation signal is thoroughly cut off when N times are exceeded.

Description

Technical Field

[0001] The present invention belongs to the technical field of accelerator physics, and particularly relates to a high-frequency cavity sparking safety interlock protection method and system, which are used to timely monitor the cavity sparking phenomenon and protect the normal-temperature high-frequency cavity equipment, preventing the performance of the high-frequency cavity from degrading or being damaged due to sparking. Background Art

[0002] For newly manufactured high-frequency copper cavities that have not undergone high-power aging or copper cavities that have been placed for a long time, sparking is likely to occur when power is fed into the high-frequency cavity. Only after undergoing a power aging process from low power to high power, and from pulsed to continuous wave, will the probability of sparking in the copper cavity be greatly reduced.

[0003] Cavity sparking can cause the vacuum in the cavity to increase and the cavity frequency to detune at the lightest, and can damage the copper cavity form and surface, affect the performance of the cavity, and even cause the copper cavity to be damaged at the heaviest. Therefore, the monitoring and timely and effective suppression measures for cavity sparking are crucial.

[0004] In order to prevent sparking from damaging the high-frequency cavity body, corresponding suppression methods need to be taken to protect the cavity. Usually, an arc probe can be installed on the cavity, which can detect whether there is an arc sparking phenomenon in the area near the arc probe in the cavity. When the arc detector monitors the sparking phenomenon, it will generate an interlock signal to timely close the main path RF switch of the high-frequency system and cut off the forward power of the power source. This method has certain limitations:

[0005] First, the detection area of the arc probe is limited and cannot completely cover the inner surface of the cavity, and it can only be installed in the areas prone to sparking.

[0006] Second, the arc detector has a certain sensitivity to arcs, and minor sparking phenomena may not be detected.

[0007] Third, after detecting sparking, the forward power will be directly turned off, resulting in a rapid drop in the water temperature. Since the frequency of the normal-temperature cavity is greatly affected by the water temperature, when power is added again after restarting the machine, the cavity frequency is severely detuned due to the change in the water temperature, and thus it takes a long time to restart the machine, seriously reducing the work efficiency. Summary of the Invention

[0008] Aiming at the deficiencies of the arc detector, the present invention provides a high-frequency cavity sparking safety interlock protection method and system. The high-frequency low-level system of the present invention determines whether there is sparking in the cavity by real-time monitoring of the changes in the incident power, reflected power, and cavity field power. When the sparking judgment condition is met, the low-level control system will generate a sparking processing logic, turn off the low-level excitation for a certain duration according to the situation, or completely turn off the low-level excitation and send the sparking interlock signal to the high-frequency safety interlock device to cut off the main path RF switch of the high-frequency system.

[0009] The high-frequency cavity ignition safety interlock protection method of the present invention is divided into two parts according to the functions: ignition event monitoring and ignition event interlock processing. The ignition event monitoring function is responsible for real-time monitoring of the relevant radio frequency signals of the high-frequency cavity, and generates an ignition event trigger signal when these signals meet the set conditions, while the ignition event interlock processing function is responsible for making corresponding action responses after receiving the ignition event trigger signal to avoid serious damage to the high-frequency cavity.

[0010] 1) Ignition event monitoring function:

[0011] During high-frequency cavity high-power conditioning, under normal circumstances, the incident power maintains a certain power value to establish a certain cavity field in the cavity. In order to perform cavity conditioning more effectively, the cavity is in a resonant state, and the reflected power at this time is maintained at a smaller power value, much lower than the incident power. If an arc ignition event suddenly occurs in the cavity at this time, the cavity will be detuned. If the forward power continues to be maintained, the reflected power will increase rapidly due to the cavity detuning, and the high-frequency cavity pressure will begin to decay. According to the above analysis, it can be determined that the incident power, reflected power and cavity field power signals meet certain relationship conditions before and after the arc ignition. Therefore, the corresponding relationship conditions are set to determine whether the arc ignition has occurred.

[0012] The high-frequency cavity ignition safety interlock protection system monitors the incident power, reflected power and cavity field power in real time, and then sends them to the FIFO with a delay of 3us and 6us respectively. The incident power, reflected power and cavity field power at the current moment are Pf, Pr and Pt respectively, the incident power, reflected power and cavity field power 3us ago are Pf_delay1, Pr_delay1 and Pt_delay1, and the incident power, reflected power and cavity field power 6us ago are Pf_delay2, Pr_delay2 and Pt_delay2. When these power quantities meet a certain relationship at the same time, the low-level control system determines that an arc ignition event has occurred, and arc ignition interlock protection processing is required.

[0013] The cavity ignition protection monitoring judgment conditions are as follows:

[0014] 1. After the cavity arc ignites, the reflected power will increase rapidly, so the current reflected power Pr will be more than k1 times the reflected power Pr_delay2 6us ago, that is, Pr>k1*Pr_delay2 is a necessary condition for cavity ignition protection, where k1 is greater than 5.

[0015] 2. After the cavity arc ignition, the reflected power will increase rapidly. Therefore, the reflected power Pr_delay1 before 3 us is more than k1 times the reflected power Pr_delay2 before 6 us, that is, Pr_delay1 > k1 * Pr_delay2 is a necessary condition for cavity ignition protection.

[0016] 3. After the cavity arc ignition, the high-frequency cavity will be detuned, and the forward power Pf cannot be fed into the high-frequency cavity to build the field, resulting in the cavity field power Pt decaying exponentially. The decay coefficient depends on the cavity quality factor of the high-frequency cavity. Therefore, the current cavity field power Pt must be less than the cavity field power Pt_delay1 before the arc ignition. That is, Pt * 10 < k2 * Pt_delay1 is a necessary condition for cavity ignition protection, where k2 is less than 10.

[0017] 4. After the cavity arc ignition, if the forward power Pf decreases significantly compared to the forward power Pf_delay1 before 3 us, no safety protection is required. Otherwise, safety protection is required. That is, Pf * 10 > k3 * Pf_delay1 is a necessary condition for cavity ignition protection, where k3 is less than 10.

[0018] 5. Safety protection is required only when the magnitude of the cavity forward power Pf exceeds a certain threshold H1. That is, when the forward power is small or there is no forward power, cavity ignition safety protection is not required.

[0019] 6. Safety protection is required only when the magnitude of the cavity field power Pt exceeds a certain threshold H2. That is, when the electric field in the cavity is small or there is no electric field, cavity ignition safety protection is not required.

[0020] When the above 6 conditions are met simultaneously, it indicates that an ignition phenomenon has occurred and safety protection is required. Otherwise, if any one of the conditions is not met, it indicates that safety protection is not required. When an ignition phenomenon is detected, the system will generate an ignition event trigger signal, which will be sent to the ignition event interlock processing section for subsequent safety interlock protection processing.

[0021] 2) Ignition event interlock processing function:

[0022] When an arc ignition event is detected, a quick response is made, which can well protect the high-frequency cavity from damage and ensure the efficiency of high-frequency cavity high-power aging. From the perspective of protecting the high-frequency cavity, when an arc ignition event occurs, directly triggering the safety interlock and cutting off the forward power is the best response. But on the other hand, because the high-frequency room temperature cavity is greatly affected by the temperature effect, once the interlock cuts off the power for a long time, the cavity will cool down rapidly, causing the cavity frequency to be detuned far beyond the bandwidth range, so that when the power is added again to build the field, it takes a long time to tune the cavity and build the field normally, which will greatly reduce the efficiency of high-power aging. In view of this, we have formed a specific arc ignition event interlock processing mechanism. Within a certain time period, when the number of ignition event trigger signals received is less than 3 times, the low-level control system only briefly cuts off the forward power excitation signal for a period of time, such as about 100us, and then quickly recovers. Since the power cut-off time is very short, the cavity temperature effect has not had time to respond, so the state of the high-frequency cavity can be quickly restored while the ignition phenomenon is eliminated; only when the ignition event trigger signal is received more than 4 times will the safety interlock be triggered, thereby completely cutting off the forward power.

[0023] The cavity ignition safety protection algorithm is implemented based on the low-level control system FPGA firmware algorithm.

[0024] The two FIFO delay times can be adjusted according to the high frequency cavity characteristics.

[0025] The k1, k2, and k3 parameters of the cavity ignition protection monitoring and judgment conditions can be adjusted online.

[0026] The power cut-off time after the first three cavity ignitions can be adjusted online separately.

[0027] The first three cavity ignitions are not interlocked and latched to prevent the cavity from cooling and causing frequency detuning.

[0028] After the fourth ignition event triggers the safety interlock, the interlock will be latched and the interlock state can only be released after resetting through a low-level control system.

[0029] The technical solution of the present invention is:

[0030] A high-frequency cavity ignition safety interlock protection method, the steps of which include:

[0031] 1) Two FIFOs are set in the low-level control system, and the incident power, reflected power and cavity field power of the high-frequency cavity are collected in real time at the sampling clock frequency of the low-level control system, and stored in the two FIFOs respectively, wherein the signal stored in one FIFO is the signal T time before the current moment, and the signal stored in the other FIFO is the signal 2T time before the current moment;

[0032] 2) The ignition event monitoring unit collects the incident power Pf, reflected power Pr, and cavity field power Pt of the high-frequency cavity at the current moment, and compares them with the incident power Pf_delay1, reflected power Pr_delay1, and cavity field power Pt_delay1 collected T time before the current moment, as well as the incident power Pf_delay2, reflected power Pr_delay2, and cavity field power Pt_delay2 collected 2T time before the current moment. If the set monitoring judgment conditions for cavity ignition protection are met, an ignition event trigger signal is generated and sent to the ignition event interlock processing unit;

[0033] 3) When the number of ignition event trigger signals received by the ignition event interlock processing unit within the set duration period does not exceed N times, the forward power excitation signal is briefly cut off and then quickly restored to eliminate the ignition phenomenon and quickly restore the state of the high-frequency cavity; when the number of ignition event trigger signals received by the ignition event interlock processing unit within the set duration period exceeds N times, the forward power excitation signal is completely cut off.

[0034] Further, the set monitoring judgment conditions for cavity ignition protection include: a) Pr > k1 * Pr_delay2; b) Pr_delay1 > k1 * Pr_delay2; c) Pt * 10 < k2 * Pt_delay1; d) Pf * 10 > k3 * Pf_delay1; e) Pf exceeds the set threshold H1; f) Pt exceeds the set threshold H2; where k1 is greater than 5, k2 is less than 10, and k3 is less than 10.

[0035] Further, the set thresholds H1 and H2 need to be set according to the specific physical performance parameters of the high-frequency cavity.

[0036] Further, the interlock processing method of the ignition event interlock processing unit is: when the i-th ignition event trigger signal is received within the set duration period and does not exceed N times, the duration of cutting off the forward power excitation signal is T i , when the (i + 1)-th ignition event trigger signal is received within the set duration period and does not exceed N times, the duration of cutting off the forward power excitation signal is T i+1 ; where T i+1 is greater than T i .

[0037] Further, T = 3us; N = 3.

[0038] A low-level control system, characterized in that it includes an ignition event monitoring unit and an ignition event interlock processing unit;

[0039] The ignition event monitoring unit is used to collect the incident power, reflected power and cavity field power of the high-frequency cavity in real time at the sampling clock frequency of the low-level control system, and store them into two FIFOs respectively. The signals stored in one FIFO are the signals at time T before the current moment, and the signals stored in the other FIFO are the signals at time 2T before the current moment; and compare the incident power Pf, reflected power Pr and cavity field power Pt of the high-frequency cavity at the current moment with the signals in the two FIFOs. If the set monitoring judgment conditions for cavity ignition protection are met, an ignition event trigger signal is generated and sent to the ignition event interlock processing unit;

[0040] The ignition event interlock processing unit is used to briefly cut off the forward power excitation signal and then quickly restore the forward power excitation signal when the number of ignition event trigger signals received within the set duration period does not exceed N times, so as to eliminate the ignition phenomenon and quickly restore the state of the high-frequency cavity; when the number of ignition event trigger signals received by the ignition event interlock processing unit within the set duration period exceeds N times, the forward power excitation signal is completely cut off.

[0041] The advantages of the present invention are as follows:

[0042] 1) The arc detector can only locally monitor the arc ignition for safety protection, while this method can monitor the arc ignition anywhere in the cavity, improving safety.

[0043] 2) The sensitivity of the arc detector to ignition is not easy to adjust. This method can adjust the arc ignition monitoring conditions online and set different ignition monitoring conditions for different cavity states.

[0044] 3) The arc detector will directly cut off the power after detecting the ignition, while this method will execute power cut-off for different durations or completely cut off the power according to different detected ignition states.

[0045] 4) Compared with the arc detector for ignition protection, it has higher working efficiency.

[0046] 5) According to different cavity types, the ignition monitoring conditions can be adjusted online. Description of the Drawings

[0047] Figure 1 It is a frame diagram of the cavity ignition safety protection algorithm.

[0048] Figure 2 It is a timing diagram of the ignition event interlock processing function. Detailed Embodiment

[0049] The present invention will be further described in detail below with reference to the drawings. The examples given are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0050] The present invention includes the following two parts:

[0051] 1. Program development

[0052] Based on the digital signal processing board of the low-level control system, develop the firmware algorithm for the cavity sparking safety protection. The block diagram of the cavity sparking safety protection algorithm is as Figure 1 shown.

[0053] Cavity sparking monitoring function part:

[0054] The system collects the incident power, reflected power, and cavity field feedback signal of the cavity, and obtains the I / Q quantities of the signals, which are I_pf, Q_pf, I_pr, Q_pr, I_pt, and Q_pt respectively. The calculation method is P = I*I + Q*Q, and the power amplitudes are calculated to obtain Pf, Pr, and Pt respectively.

[0055] The obtained power quantities Pf, Pr, and Pt are sent to the FIFO with a delay of 3us to obtain Pf_delay1, Pr_delay1, and Pt_delay1.

[0056] The obtained power quantities Pf, Pr, and Pt are sent to the FIFO with a delay of 6us to obtain Pf_delay2, Pr_delay2, and Pt_delay2.

[0057] When the measured power quantities meet the conditions of (1.1) to (1.6), it indicates that a sparking phenomenon has occurred, and the sparking event trigger signal Arc is output. Among them, k1, k2, k3, H1, and H2 are set constant parameters, which can be set through the upper-layer OPI interface of the low-level system. H1 and H2 are the thresholds of the forward power Pf and the cavity field power Pt respectively, and the set values can be set according to the specific physical characteristics of the high-frequency cavity.

[0058] Pr > k1 * Pr_delay2 (1.1)

[0059] Pr_delay1 > k1 * Pr_delay2 (1.2)

[0060] Pt * 10 < k2 * Pt_delay1 (1.3)

[0061] Pf * 10 > k3 * Pf_delay1 (1.4)

[0062] Pf > H1 (1.5)

[0063] Pt > H2 (1.6)

[0064] Sparking event interlock processing function part:

[0065] The timing diagram of the interlock processing function for the arc ignition event is as follows Figure 2 shown. The fixed-duration pulse ignition trigger signal Arc_trig is generated by the rising edge of the Arc ignition signal (ignition event trigger signal). When the Arc_trig signal is detected as high level, the count signal Count is incremented by 1. In the initial state, the Count signal is 0. When the count signal Count is zero, if the rising edge of the ignition event trigger signal is monitored at this time, the trigger cycle signal Cycle is set to high level and maintained for a duration of Tc. After the Cycle signal becomes low level, the trigger count signal Count is reset to zero and the Arc ignition counting starts again. Shut is the power-off signal. During the period when Cycle is high level, when the first ignition event occurs, the Count signal is set to 1 and the Shut signal is set to 0 for a duration of T1. The forward power is cut off during the T1 duration and then the forward power is immediately restored. And so on, the second cut-off duration is T2 and the third cut-off duration is T3. When the fourth ignition event occurs, the ignition interlock signal Interlock is triggered, causing safety interlock protection and directly cutting off the low-level excitation. It can only return to normal after the high-frequency system is reset. The cut-off durations T1, T2, T3 are register set values and can be adjusted in real time through the upper-layer OPI.

[0066] 2. Hardware and software implementation

[0067] After integrating the cavity arc ignition safety protection algorithm into the firmware algorithm of the low-level control system, the low-level system is restarted. The low-level system accesses the incident power, reflected power, and cavity field power signals of the high-frequency cavity, and the arc ignition safety interlock output signal is taken out and then input to the low-level interlock chassis.

[0068] PV quantities corresponding to the adjustable parameters K1, K2, K3, T1, T2, T3 are added to the database db file of the low-level IOC application. The address corresponds to the register address of the corresponding parameter in the FPGA algorithm. PV controls are added to the upper layer of the OPI to implement the setting of the parameters K1, K2, K3, T1, T2, T3.

[0069] Taking the low-level system as the control main body, the high-power aging of the high-frequency cavity and the arc ignition safety interlock protection are realized. The parameters K1, K2, K3, T1, T2, T3 are adjusted online to set appropriate parameters for the arc ignition safety interlock protection algorithm of the high-frequency cavity.

[0070] Although specific embodiments of the present invention are disclosed for illustrative purposes, which are intended to help understand the content of the present invention and implement it accordingly, those skilled in the art can understand that various substitutions, changes, and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the content disclosed in the preferred embodiments, and the scope of protection claimed by the present invention shall be defined by the scope defined in the claims.

Claims

1. A high-frequency cavity sparking safety interlock protection method, the steps of which include: 1) Set two FIFOs in the low-level control system, and collect the incident power, reflected power, and cavity field power of the high-frequency cavity in real time at the sampling clock frequency of the low-level control system, and store them into the two FIFOs respectively. The signals stored in one FIFO are the signals at time T before the current moment, and the signals stored in the other FIFO are the signals at time 2T before the current moment; 2) The sparking event monitoring unit collects the incident power Pf, reflected power Pr, and cavity field power Pt of the high-frequency cavity at the current moment, and compares them with the incident power Pf_delay1, reflected power Pr_delay1, and cavity field power Pt_delay1 collected at time T before the current moment, as well as the incident power Pf_delay2, reflected power Pr_delay2, and cavity field power Pt_delay2 collected at time 2T before the current moment. If the set cavity sparking protection monitoring judgment conditions are met, a sparking event trigger signal is generated and sent to the sparking event interlock processing unit; 3) When the number of sparking event trigger signals received by the sparking event interlock processing unit within the set time period does not exceed N times, the forward power excitation signal is briefly cut off and then quickly restored to eliminate the sparking phenomenon and quickly restore the state of the high-frequency cavity; when the number of sparking event trigger signals received by the sparking event interlock processing unit within the set time period exceeds N times, the forward power excitation signal is completely cut off.

2. The method according to claim 1, characterized in that The set cavity sparking protection monitoring judgment conditions include: a) Pr > k1 * Pr_delay2; b) Pr_delay1 > k1 * Pr_delay2; c) Pt * 10 < k2 * Pt_delay1; d) Pf * 10 > k3 * Pf_delay1; e) Pf exceeds the set threshold H1; f) Pt exceeds the set threshold H2; where k1 is greater than 5, k2 is less than 10, and k3 is less than 10.

3. The method according to claim 2, wherein The set thresholds H1 and H2 need to be set according to the specific physical performance parameters of the high-frequency cavity.

4. The method according to claim 1 or 2 or 3, characterized in that The interlock processing method of the ignition event interlock processing unit is as follows: when the i-th ignition event trigger signal is received within the set duration period and does not exceed N times, the duration of the forward power excitation signal cut-off is T i , when the (i + 1)-th ignition event trigger signal is received within the set duration period and does not exceed N times, the duration of the forward power excitation signal cut-off is T i+1 ; where T i+1 is greater than T i .

5. The method according to claim 1 or 2 or 3, characterized in that, T = 3us; N = 3.

6. A low-level control system, characterized in that, It includes a sparking event monitoring unit and a sparking event interlock processing unit; The sparking event monitoring unit is used to collect the incident power, reflected power, and cavity field power of the high-frequency cavity in real time at the sampling clock frequency of the low-level control system, and store them into the two FIFOs respectively. The signals stored in one FIFO are the signals at time T before the current moment, and the signals stored in the other FIFO are the signals at time 2T before the current moment; and compare the incident power Pf, reflected power Pr, and cavity field power Pt of the high-frequency cavity at the current moment with the signals in the two FIFOs. If the set cavity sparking protection monitoring judgment conditions are met, a sparking event trigger signal is generated and sent to the sparking event interlock processing unit; The ignition event interlock processing unit is configured to briefly cut off the forward power excitation signal and then quickly restore the forward power excitation signal when the number of ignition event trigger signals received within a set duration period does not exceed N times, so as to eliminate the ignition phenomenon and quickly restore the state of the high-frequency cavity; when the number of ignition event trigger signals received by the ignition event interlock processing unit within the set duration period exceeds N times, the forward power excitation signal is completely cut off.

7. The system according to claim 6, characterized in that, The set monitoring and judgment conditions for cavity ignition protection include: a) Pr > k1 * Pr_delay2; b) Pr_delay1 > k1 * Pr_delay2; c) Pt * 10 < k2 * Pt_delay1; d) Pf * 10 > k3 * Pf_delay1; e) Pf exceeds the set threshold H1; f) Pt exceeds the set threshold H2; where k1 is greater than 5, k2 is less than 10, k3 is less than 10, Pf_delay1, Pr_delay1, and Pt_delay1 are the incident power, reflected power, and cavity field power collected at time T before the current moment respectively, and Pf_delay1, Pr_delay1, and Pt_delay1 are the incident power, reflected power, and cavity field power collected at time 2T before the current moment respectively.

8. The system according to claim 7, wherein The set thresholds H1 and H2 need to be set according to the specific physical performance parameters of the high-frequency cavity.

9. The system according to claim 6 or 7 or 8, characterized in that, The interlock processing method of the ignition event interlock processing unit is as follows: when the i-th ignition event trigger signal is received within the set duration period and does not exceed N times, the duration of cutting off the forward power excitation signal is T i , when the (i + 1)-th ignition event trigger signal is received within the set duration period and does not exceed N times, the duration of cutting off the forward power excitation signal is T i+1 ; where T i+1 is greater than T i .

10. The system according to claim 6 or 7 or 8, characterized in that, T = 3us; N = 3.

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