CN105517314B - A kind of accelerating tube vacuum-ness detecting device of linear accelerator - Google Patents

Abstract

The invention provides a vacuum detection device for an accelerating tube of a linear accelerator, comprising: a titanium pump, an accelerating tube, a current detection module and a host computer; the current detection module is located in the treatment room where the linear accelerator is located, and the host computer is located outside the treatment room; the titanium pump, Used to maintain the vacuum state in the accelerating tube; the current detection module is used to obtain the titanium pump current from the working power supply of the titanium pump, and the titanium pump current represents the vacuum degree of the accelerating tube; the host computer is used to receive the titanium pump output by the current detection module Current, the vacuum degree of the accelerating tube is judged by the current of the titanium pump. When it is judged that the current of the titanium pump is higher than the current preset value, the accelerating tube is controlled to stop working. The interior of the titanium pump and the accelerating tube is connected. The current of the titanium pump can represent the vacuum degree in the accelerating tube. The current of the titanium pump is detected to monitor the vacuum degree of the accelerating tube. When the detected current of the titanium pump is higher than the current preset value, it indicates acceleration. The vacuum in the tube cavity does not meet the requirements, and the vacuum is low. At this time, it is necessary to control the acceleration tube to stop working.

Description

A device for detecting the vacuum degree of an accelerating tube of a linear accelerator

technical field

The invention relates to the technical field of medical equipment, in particular to a device for detecting the vacuum degree of an accelerating tube of a linear accelerator.

Background technique

When the accelerating tube of the medical electron linear accelerator is working, the inside of the cavity must be kept in a high vacuum state, that is, the atmospheric pressure of 1.333*10 ^-5 Pa needs to be kept. Only in a high vacuum state can a high electric field be established in the cavity of the accelerating tube without sparking, and at the same time prevent poisoning and pollution of the cathode of the electron gun. Because the price of the accelerating tube is relatively high, the price of one accelerating tube is more than 200,000 yuan. Therefore, it is necessary to detect the vacuum degree in the cavity of the accelerating tube to judge the working state of the accelerating tube, so as to prevent the accelerating tube from being damaged due to the low vacuum in the cavity.

Therefore, those skilled in the art need to provide a device for detecting the vacuum degree of the accelerating tube of the linear accelerator, which can accurately detect the vacuum degree of the accelerating tube.

Contents of the invention

The technical problem to be solved by the present invention is to provide a vacuum degree detection device for an accelerating tube of a linear accelerator, which can accurately detect the vacuum degree of the accelerating tube.

An embodiment of the present invention provides a vacuum detection device for an accelerating tube of a linear accelerator, including: a titanium pump, an accelerating tube, a current detection module, and a host computer;

The current detection module is located in the treatment room where the linear accelerator is located, and the host computer is located outside the treatment room;

The titanium pump is used to maintain the vacuum state in the accelerating tube;

The current detection module is used to obtain the titanium pump current from the working power supply of the titanium pump, and the titanium pump current represents the vacuum degree of the accelerating tube;

The upper computer is used to receive the titanium pump current output by the current detection module, judge the vacuum degree of the accelerating tube through the titanium pump current, and control the The accelerator tube stops working.

Preferably, the current detection module includes: a sampling interface circuit;

The sampling interface circuit includes a first chip and a current sampling resistor;

The function of the first chip is to convert the input voltage into the working voltage required by the titanium pump;

The positive output terminal of the first chip is connected to the titanium pump, and the negative output terminal of the first chip is grounded through the current sampling resistor;

The current flowing through the current sampling resistor is collected to characterize the vacuum degree of the accelerating tube.

Preferably, the current detection module further includes: a first-stage amplifying circuit, a filter circuit and a second-stage amplifying circuit;

The voltage on the current sampling resistor is input into the first-stage amplifying circuit;

The first-stage amplifying circuit is used for first-stage amplification of the voltage on the current sampling resistor;

The filter circuit is used to filter out the interference signal in the signal output by the first-stage amplifying circuit;

The second-stage amplifying circuit is configured to perform second-stage amplification on the signal output by the filter circuit.

Preferably, the current detection module further includes: a current signal transmission circuit;

The current signal transmission circuit includes: a first amplifier and a second amplifier;

The output terminal of the second-stage amplifying circuit is connected to the non-inverting input terminal of the first amplifier through a fifteenth resistor; the inverting input terminal of the first amplifier is connected to the output terminal of the first amplifier through a fourth resistor;

The output terminal of the first amplifier is connected to the non-inverting input terminal of the second amplifier through a twelfth resistor, and the inverting input terminal of the second amplifier is connected to the output terminal of the second amplifier;

The current of the non-inverting input terminal of the second amplifier is sent to the host computer.

Preferably, it also includes: a voltage ammeter driving circuit;

The voltage ammeter drive circuit includes: a third amplifier, a fourth amplifier, a fifth amplifier and a sixth amplifier;

The voltage on the current sampling resistor is input to the non-inverting input terminal of the third amplifier, and the inverting input terminal of the third amplifier is connected to the output terminal of the third amplifier;

The middle tap output end of the first chip is connected to the non-inverting input end of the fourth amplifier, the inverting input end of the fourth amplifier is connected to the output end of the fourth amplifier, and the middle tap of the first chip The output voltage is one-thousandth of the voltage output by the positive output terminal of the first chip;

The output terminal of the third amplifier is connected to the non-inverting input terminal of the fifth amplifier through the twenty-second resistor, and the output terminal of the fourth amplifier is connected to the inverting input terminal of the fifth amplifier through the twenty-ninth resistor end;

The output terminal of the fifth amplifier is connected to the non-inverting input terminal of the sixth amplifier, and the inverting input terminal of the sixth amplifier is connected to the output terminal of the sixth amplifier;

The output end of the sixth amplifier is connected to a voltage ammeter.

Preferably, it also includes: an interlocking control circuit;

The chain control circuit includes: a seventh comparator, an eighth comparator and an optocoupler;

The inverting input terminal of the seventh comparator is connected to the output terminal of the fifth amplifier; the non-inverting input terminal of the seventh comparator is connected to the voltage difference of the first chip; the voltage of the first chip The difference is the difference between the voltage output by the middle tap of the first chip and the voltage output by the negative output terminal of the first chip;

The output terminal of the seventh comparator is connected to the inverting input terminal of the eighth comparator, and the non-inverting input terminal of the eighth comparator is connected to the reference voltage; the output terminal of the eighth comparator is connected to the optical The anode of the light-emitting diode of the coupling; the cathode of the light-emitting diode of the optocoupler is grounded;

The first output end of the optocoupler is connected to the power supply, and the second output end of the optocoupler is connected to the host computer;

The host computer is configured to control the acceleration tube to stop working when judging that the signal output by the second output terminal of the optocoupler is a valid signal.

Preferably, it also includes: a seventh amplifier;

The seventh amplifier is used to amplify the voltage difference of the first chip and connect it to the non-inverting input terminal of the seventh comparator.

Preferably, the filter circuit is a low-pass filter circuit, and the low-pass filter circuit includes: an eighth resistor, a ninth resistor, and a sixth capacitor;

The first end of the eighth resistor is connected to the output end of the first-stage amplifying circuit, and the second end of the eighth resistor is connected to the first end of the ninth resistor;

The second end of the ninth resistor is connected to the input end of the second-stage amplifying circuit;

The second end of the eighth resistor is grounded through the sixth capacitor.

Preferably, the first-stage amplifying circuit includes: a first amplifying chip, a second resistor and a third resistor;

The voltage on the current sampling resistor is input to the non-inverting input terminal of the first amplifying chip, the inverting input terminal of the first amplifying chip is grounded through the second resistor; the output terminal of the first amplifying chip is grounded through the third The resistor is connected to the inverting input terminal of the first amplifier chip.

Preferably, the filter circuit is a low-pass filter circuit;

The low-pass filter circuit includes: an eighth resistor, a ninth resistor and a sixth capacitor;

The first end of the eighth resistor is connected to the output end of the first-stage amplifying circuit, and the second end of the eighth resistor is connected to the first end of the ninth resistor;

The second end of the ninth resistor is connected to the input end of the second-stage amplifying circuit;

The second end of the eighth resistor is grounded through the sixth capacitor.

Compared with the prior art, the present invention has the following advantages:

In the detection device provided by the embodiment of the present invention, the interior of the titanium pump and the acceleration tube are connected, and the titanium pump can keep the inside of the acceleration tube in a vacuum state. Since the current of the titanium pump can represent the vacuum degree in the acceleration tube, the device can obtain the vacuum from the titanium pump. The titanium pump current is obtained from the working power supply. The smaller the titanium pump current is, the higher the vacuum degree in the accelerating tube is, and the larger the titanium pump current is, the lower the vacuum degree in the accelerating tube is. Therefore, the present invention monitors the vacuum degree of the accelerating tube by detecting the titanium pump current. When the detected titanium pump current is higher than the current preset value, it indicates that the vacuum degree in the cavity of the accelerating tube does not meet the requirements and the vacuum degree is relatively low. Control the acceleration tube to stop working.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a schematic diagram of Embodiment 1 of an accelerating tube vacuum detection device of a linear accelerator provided by the present invention;

Fig. 2 is a schematic diagram of a sampling interface circuit provided by the present invention;

Fig. 3 is a schematic diagram of the amplifying drive circuit in the current detection module provided by the present invention;

4 is a schematic diagram of a current signal transmission circuit provided by the present invention;

Fig. 5 is a schematic diagram of a voltage ammeter drive circuit provided by the present invention;

Fig. 6 is a schematic diagram of the chain control circuit provided by the present invention.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In order to make the above objects, features and advantages of the present invention more comprehensible, specific implementations of the present invention will be described in detail below in conjunction with the accompanying drawings.

Referring to FIG. 1 , this figure is a schematic diagram of Embodiment 1 of an accelerating tube vacuum degree detection device of a linear accelerator provided by the present invention.

A device for detecting the vacuum degree of an accelerating tube of a linear accelerator, comprising: an accelerating tube 100, a titanium pump 200, a current detection module 300, and a host computer 400;

In addition, the normal operation of the medical electron linear accelerator requires the microwave power source 500 to provide power for the magnetron 600, and the magnetron 600 forms a magnetic field.

The current detection module 300 is located in the treatment room where the linear accelerator is located, and the host computer 400 is located outside the treatment room;

It can be understood that the output of the linear accelerator is X-rays with relatively large radiation, and it is located in the treatment room, while medical personnel are generally located outside the treatment room.

It can be understood that both the accelerating tube 100 and the titanium pump 200 are components for the linear accelerator to generate accelerated electrons.

The titanium pump 200 is used to maintain the vacuum state in the accelerating tube 100;

The titanium pump, also known as the sputtering ion pump, is integrated with the accelerating tube and is a device used to maintain a high vacuum in the accelerating tube. The electrical control system needs to provide a DC high voltage power supply for the titanium pump. Due to the differences of the accelerating tubes, different accelerating tubes require different titanium pumps. For example, some accelerators require a DC power supply of 3500V-4000V from the titanium pump. In order to prevent the cavity of the accelerating tube and the cathode of the electron gun from being poisoned, avoid the discharge breakdown in the accelerating tube, and reduce the energy loss caused by the collision between electrons and the residual gas in the accelerating tube, the accelerating tube must maintain a high vacuum state.

When the accelerating tube is in a static state (that is, the electron gun filament of the accelerating tube has been preheated), the current of the titanium pump is less than 10uA, and when the accelerating tube is in a dynamic state (during the beam output of the accelerating tube), the current of the titanium pump does not exceed 20uA.

The current detection module 300 is used to obtain the titanium pump current from the working power supply of the titanium pump 200, and the titanium pump current represents the vacuum degree of the accelerating tube 100;

Since the titanium pump current can represent the vacuum degree of the accelerating tube 100, the method adopted in the present invention is to measure the titanium pump current.

The upper computer 400 is used to receive the titanium pump current output by the current detection module 300, judge the vacuum degree of the acceleration tube through the titanium pump current, and when it is judged that the titanium pump current is higher than the current preset value , to control the acceleration tube to stop working.

In the detection device provided by the embodiment of the present invention, the interior of the titanium pump and the acceleration tube are connected, and the titanium pump can keep the inside of the acceleration tube in a vacuum state. Since the current of the titanium pump can represent the vacuum degree in the acceleration tube, the device can obtain the vacuum from the titanium pump. The titanium pump current is obtained from the working power supply. The smaller the titanium pump current is, the higher the vacuum degree in the accelerating tube is, and the larger the titanium pump current is, the lower the vacuum degree in the accelerating tube is. Therefore, the present invention monitors the vacuum degree of the accelerating tube by detecting the titanium pump current. When the detected titanium pump current is higher than the current preset value, it indicates that the vacuum degree in the cavity of the accelerating tube does not meet the requirements and the vacuum degree is relatively low. Control the acceleration tube to stop working.

Because the working voltage of the titanium pump is relatively high, for example, the titanium pump may need a DC high voltage of 3800V in actual work, and it is generally difficult to sample at such a high voltage. In order to ensure the accuracy of the sampling signal, the present invention designs a special sampling interface circuit, which will be described in detail below in conjunction with the accompanying drawings.

Referring to FIG. 2 , this figure is a schematic diagram of a sampling interface circuit provided by the present invention.

In this embodiment, the current detection module includes: a sampling interface circuit;

As shown in Figure 2, the sampling interface circuit includes a first chip U1 and a current sampling resistor R11;

It should be noted that the function of the first chip U1 is to convert the input voltage into the working voltage required by the titanium pump; that is, U1 is a boost chip, and its main function is to convert the input low voltage into a high voltage output.

In this embodiment, the input voltage of U1 is 24V as an example for introduction. It can be understood that the input voltage can take different values according to the specific circuit design. 24V is a power supply voltage on the circuit control board provided by the present invention.

The positive output terminal OUT+ of the first chip U1 is connected to the titanium pump, and the negative output terminal of the first chip U1 is grounded through the current sampling resistor R11;

The current flowing through the current sampling resistor R11 is collected to characterize the vacuum degree of the accelerating tube.

U1 has two inputs and three outputs. That is, IN+ of U1 is connected to +24V, IN- of U1 is grounded; OUT+ of U1 is the positive output terminal of the power supply, for example, 3800V. OUT- of U1 is the negative output terminal of the power supply, and MTR+ of U1 is the output terminal of the middle tap. In this embodiment, the output voltage of MTR+ is one-thousandth of the output voltage of U1.

The positive end of the titanium pump is connected to the OUT+ of U1 through a high-voltage coaxial cable. If the positive end of the titanium pump is directly detected, the voltage is too high, and it is too difficult to achieve high-voltage electrical isolation; while the negative end of the titanium pump is connected to the protective ground, and it is reliable. The ground is connected to the ground, so the current detection of the accelerating tube cannot be performed at the negative end of the titanium pump.

Therefore, in this embodiment, the current sampling resistor R11 is connected between the negative output terminal OUT- of U1 and the ground, and the voltage value HV_OUT on R11 is finally collected. Since the resistance value of R11 is known, HV_OUT The value of the current value flowing through R11 can be obtained, that is, the titanium pump current.

The current of the titanium pump is very small, that is, the current in the corresponding acceleration lumen is also very small. When the current in the acceleration lumen exceeds the current preset value, it means that the vacuum degree in the acceleration lumen is low, for example, the current preset value is 5uA. Therefore, the detected titanium pump current is also very small. In order to identify the current signal with a smaller order of magnitude, it is necessary to amplify and filter the sampled current, which will be described in detail below with reference to the accompanying drawings.

Referring to FIG. 3 , this figure is a schematic diagram of the amplification driving circuit in the current detection module provided by the present invention.

The current detection module also includes: a first-stage amplifying circuit, a filter circuit and a second-stage amplifying circuit;

The voltage on the current sampling resistor is input into the first-stage amplifying circuit;

The first-stage amplifying circuit is used for first-stage amplification of the voltage on the current sampling resistor;

The filter circuit is used to filter out the interference signal in the signal output by the first-stage amplifying circuit;

The second-stage amplifying circuit is used to perform second-stage amplification on the signal output by the filter circuit;

As shown in FIG. 3, the first-stage amplifying circuit includes a first amplifying chip U2, a second resistor R2, and a third resistor R3;

The voltage HV_OUT on the current sampling resistor R11 is input to the first-stage amplifying circuit, that is, HV_OUT- is connected to the non-inverting input terminal of U2, and the inverting input terminal of U2 is grounded through the second resistor R2; the output terminal of U2 is grounded through the third resistor R3 is connected to the inverting input of U2;

It should be noted that since the minimum titanium pump current is on the order of nA, U2 needs to choose an operational amplifier chip with a small bias current. It is required that the bias current of U2 does not exceed 100pA, and the offset voltage of U2 does not exceed 5uA.

The filter circuit is a low-pass filter circuit, and the low-pass filter circuit includes: an eighth resistor R8, a ninth resistor R9, and a sixth capacitor C6;

The first end of the eighth resistor R8 is connected to the output end of the first-stage amplifying circuit, and the second end of the eighth resistor R8 is connected to the first end of the ninth resistor R9;

The second end of the ninth resistor R9 is connected to the input end of the second-stage amplifying circuit;

The second end of the eighth resistor R8 is grounded through the sixth capacitor C6.

The role of the low-pass filter circuit is to filter out interference signals.

The second-stage amplifying circuit includes: a sixth resistor R6 and an eighth amplifier N4;

The output terminal of the filter circuit is connected to the inverting input terminal of the eighth amplifier N4, and the inverting input terminal of the eighth amplifier N4 is connected to the output terminal of the eighth amplifier N4 through the sixth resistor R6;

It should be noted that HV_OUT- is amplified 10 times by the first-stage amplifier circuit and the second-stage amplifier circuit. For example, the resistance value of R11 is 500k ohms. When the current flowing through R11 is 10nA, the voltage drop on R11 is 5mV, magnified 10 times to 50mV. When the current flowing through R11 is 1uA, the voltage drop across R11 is 500mV, which is 5V after being magnified 10 times.

Therefore, the range of the voltage signal output by the second-stage amplifying circuit in FIG. 3 is 50mV-5V, and the corresponding titanium pump current range is 10nA-1uA.

Wherein, the first-stage amplifying circuit can be amplified by 5 times, for example, the titanium pump current is 5nA, and the voltage drop across R11 is 2.5mV. The first-stage amplifying circuit is amplified 5 times to 12.5mV. Therefore, the eighth amplifier in the second-stage amplifying circuit needs to select an amplifier with a small offset voltage. The offset voltage of a general amplifier is about 10 mV, so such an amplifier cannot be selected. The offset voltage of N4 in this embodiment is lower than 75uV. Only in this way can the output voltage signal be amplified without distortion, so that the signal amplitude can meet the requirements of signal transmission.

The amplifying driving circuit provided in this embodiment can amplify the nA-level weak current detected by the sampling interface circuit.

It should be noted that the signal output by the circuit shown in Figure 3 needs to be sent to the host computer outside the treatment room. Because the radiation in the linear accelerator treatment room is relatively large, the host computer is generally far away from the treatment room, generally about 30 meters away. Therefore, it is necessary to use a small signal transmission circuit to transmit the titanium pump current of the collected small signal to the host computer outside the treatment room. The accompanying drawings are introduced below to introduce the current signal transmission circuit provided by the present invention in detail.

Referring to FIG. 4 , this figure is a schematic diagram of a current signal transmission circuit provided by the present invention.

The current detection module provided by the present invention also includes: a current signal transmission circuit;

The current signal transmission circuit includes: a first amplifier N3A and a second amplifier N3B;

The output terminal VACMETER of the second-stage amplifying circuit is connected to the non-inverting input terminal of the first amplifier N3A through the fifteenth resistor R15; the inverting input terminal of the first amplifier N3A is connected to the first amplifier through the fourth resistor R4 output of N3A;

The output terminal of the first amplifier N3A is connected to the non-inverting input terminal of the second amplifier N3B through the twelfth resistor R12, and the inverting input terminal of the second amplifier N3B is connected to the output terminal of the second amplifier N3B;

The current CURRENT of the non-inverting input terminal of the second amplifier N3B is sent to the host computer.

It should be noted that what N3A and N3B are composed of is a current loop circuit. Since the voltage drop attenuation is relatively large during the cable transmission process of the voltage signal, and the current signal is suitable for long-distance transmission, and the loss is relatively small, so in this embodiment, the current loop circuit provided in Figure 4 is used to transmit the signal to the host computer in the form of current.

Among them, the loss voltage of N3A and N3B needs to be lower than 3mV. Thus ensuring that the current signal is transmitted to the host computer without distortion.

When the host computer judges that the titanium pump current CURRENT received is higher than the current preset value, it controls the acceleration tube to stop working.

It should be noted that, in addition to detecting the current of the titanium pump through the host computer, the present invention can also detect intuitively through the voltage and current meter. The driving circuit of the voltage and current meter will be described in detail below with reference to the accompanying drawings.

Referring to FIG. 5 , this figure is a schematic diagram of a driving circuit for a voltage-ammeter provided by the present invention.

The voltage-ammeter drive circuit includes: a third amplifier U4, a fourth amplifier N2C, a fifth amplifier N1B and a sixth amplifier N1A;

The voltage HV_OUT- on the current sampling resistor is input to the non-inverting input terminal of the third amplifier U4, and the inverting input terminal of the third amplifier U4 is connected to the output terminal of the third amplifier U4;

The middle tap output terminal MTR+ of the first chip is connected to the non-inverting input terminal of the fourth amplifier N2C, the inverting input terminal of the fourth amplifier N2C is connected to the output terminal of the fourth amplifier N2C, and the first The voltage output by the middle tap of the chip is one-thousandth of the voltage output by the positive output terminal of the first chip;

The output terminal of the third amplifier U4 is connected to the non-inverting input terminal of the fifth amplifier N1B through the twenty-second resistor, and the output terminal of the fourth amplifier N2C is connected to the fifth amplifier N1B through the twenty-ninth resistor The inverting input terminal of

The output terminal of the fifth amplifier N1B is connected to the non-inverting input terminal of the sixth amplifier N1A, and the inverting input terminal of the sixth amplifier N1A is connected to the output terminal of the sixth amplifier N1A;

The output terminal of the sixth amplifier N1A is connected to a voltage and ammeter.

It should be noted that since the MTR+ output voltage of the first chip U1 is one-thousandth of the OUT+ voltage, if OUT+ is 3800V, the MTR+ output voltage is 3.8V.

It can be seen from Figure 5 that the output terminals of U4 and N2C are both connected to their own inverting input terminals, that is, the structure of an emitter follower is formed, thereby increasing the input impedance of the differential signal input terminal. The differential signals refer to MTR+ and HV_OUT-.

It can be understood that the method for avoiding common-mode interference signals is to use differential transmission. In this embodiment, the two signals MTR+ and HV_OUT- are isolated by an emitter follower to prevent signal interference. The purpose of increasing the input impedance of the differential signal is to avoid the passage of a large current, thereby increasing the input voltage of the amplifier.

It should be noted that the output signal VOL in Figure 5 can be connected to a voltage-ammeter to read both the current value and the voltage value. Medical personnel can intuitively observe the voltage and current values from the voltage-ammeter. Abnormal voltage will cause poor vacuum of the accelerating tube, and abnormal current will also cause poor vacuum of the accelerating tube. Therefore, you can use the voltage ammeter to observe whether the vacuum degree of the accelerating tube is poor due to abnormal voltage or abnormal current.

The detection device provided by the embodiment of the present invention monitors the voltage of the titanium pump in addition to the current of the titanium pump. If one of the two has a problem, both control the acceleration tube to stop working. The chain control circuit will be introduced in detail below in conjunction with the accompanying drawings.

Referring to Fig. 6, this figure is a schematic diagram of the chain control circuit provided by the present invention.

It should be noted that, in the embodiment provided in FIG. 6 , the host computer can control the acceleration tube to stop working when the voltage of the titanium pump is abnormal and/or the current has a problem. However, in the embodiment shown in Fig. 4, the upper computer only receives the current signal, and when there is a problem with the current of the titanium pump, it controls the acceleration tube to stop working.

The device provided by this embodiment also includes an interlocking control circuit.

As shown in Figure 6, the interlocking control circuit includes: a seventh comparator N2D, an eighth comparator N2A and an optocoupler D1;

The inverting input terminal of the seventh comparator N2D is connected to the output terminal of the fifth amplifier (that is, N1B in FIG. 5 ); the non-inverting input terminal of the seventh comparator N2D is connected to the intermediate voltage difference, and the The intermediate voltage difference is the difference between the voltage output by the intermediate tap MTR+ of the first chip U1 and the voltage HV_OUT- output by the negative output terminal of the first chip U1;

The output terminal of the seventh comparator N2D is connected to the inverting input terminal of the eighth comparator N2A, and the non-inverting input terminal of the eighth comparator N2A is connected to a reference voltage; the output terminal of the eighth comparator N2A Connect the anode of the light-emitting diode of the optocoupler D1; the cathode of the light-emitting diode of the optocoupler D1 is grounded;

Due to the fluctuation of the voltage of MTR+, the fluctuation range is: 3.8V-4.25V. Therefore, two reference voltages are set in the present invention, which are ALARM1 and ALARM2 respectively.

The following takes the value of ALARM2 as an example to illustrate:

When MTR+ is 3.8V, its voltage value in 5uA state is: 2.5V+3.8V＝6.3V;

When MTR+ is 4.25V, its voltage value in 5uA state is: 2.5V+4.25V＝6.75V;

Therefore, the value of ALARM2 should be between 6.3V and 6.75V, so the value is 6.54V.

It should be noted that, the reference voltage ALARMH connected to the positive phase input terminal of N2A can choose ALARM1 or ALARM2.

The first output end of the optocoupler D1 is connected to a power supply, and the second output end of the optocoupler D1 is connected to the host computer;

The host computer is configured to control the acceleration tube to stop working when judging that the signal output by the second output terminal of the optocoupler D1 is a valid signal.

If the input signal pin 3 of N2A is greater than the input signal pin 2-, the output signal of N2A is a positive voltage signal, that is, it does not exceed the 5uA threshold range, the input pin 1 and pin 2 of the optocoupler D1 are turned on, and the output terminal of the optocoupler D1 If pin 5 and pin 4 are turned on, the host computer will get 24V signal.

If the input signal pin 3 of N2A is less than the input signal pin 2-, the output signal of N2A is a negative voltage signal, that is, it exceeds the 5uA threshold range, and the input pin 1 and pin 2 of the optocoupler D1 at the back are cut off, and the output of optocoupler D1 If pin 5 and pin 4 of the terminal are disconnected, the host computer will receive the ILVAC1 signal and perform a chain alarm, that is, it is judged that there is a problem with the vacuum degree of the acceleration tube, and it is necessary to control the acceleration tube to stop working.

The detection device provided by the above embodiments of the present invention can effectively detect the problem of poor vacuum degree of the accelerating tube when the voltage or current of the titanium pump has a problem, so as to control the stopping of the accelerating tube and avoid damage to the accelerating tube.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with the art, without departing from the scope of the technical solution of the present invention, can use the methods and technical content disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent of equivalent change Example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, which do not deviate from the technical solution of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims (9)

1. An accelerating tube vacuum detection device of a linear accelerator, comprising: a titanium pump, an accelerating tube, a current detection module and a host computer; The current detection module is located in the treatment room where the linear accelerator is located, and the host computer is located outside the treatment room; The titanium pump is used to maintain the vacuum state in the accelerating tube; The current detection module is used to obtain the titanium pump current from the working power supply of the titanium pump, and the titanium pump current represents the vacuum degree of the accelerating tube; The upper computer is used to receive the titanium pump current output by the current detection module, judge the vacuum degree of the accelerating tube through the titanium pump current, and control the The acceleration tube stops working; The current detection module includes: a sampling interface circuit; The sampling interface circuit includes a first chip and a current sampling resistor; the first chip is a DC boost chip; The function of the first chip is to convert the input voltage into the working voltage required by the titanium pump; The positive output terminal of the first chip is connected to the titanium pump, and the negative output terminal of the first chip is grounded through the current sampling resistor; The current flowing through the current sampling resistor is collected to characterize the vacuum degree of the accelerating tube. 2. The vacuum detection device of the accelerating tube of the linear accelerator according to claim 1, wherein the current detection module further comprises: a first-stage amplifying circuit, a filter circuit and a second-stage amplifying circuit; The voltage on the current sampling resistor is input into the first-stage amplifying circuit; The first-stage amplifying circuit is used for first-stage amplification of the voltage on the current sampling resistor; The filter circuit is used to filter out the interference signal in the signal output by the first-stage amplifying circuit; The second-stage amplifying circuit is configured to perform second-stage amplification on the signal output by the filter circuit. 3. The vacuum detection device of the accelerating tube of the linear accelerator according to claim 2, wherein the current detection module further comprises: a current signal transmission circuit; The current signal transmission circuit includes: a first amplifier and a second amplifier; The output terminal of the second-stage amplifying circuit is connected to the non-inverting input terminal of the first amplifier through a fifteenth resistor; the inverting input terminal of the first amplifier is connected to the output terminal of the first amplifier through a fourth resistor; The output terminal of the first amplifier is connected to the non-inverting input terminal of the second amplifier through a twelfth resistor, and the inverting input terminal of the second amplifier is connected to the output terminal of the second amplifier; The current of the non-inverting input terminal of the second amplifier is sent to the host computer. 4. The vacuum detection device of the accelerating tube of the linear accelerator according to claim 1, further comprising: a voltage ammeter driving circuit; The voltage ammeter drive circuit includes: a third amplifier, a fourth amplifier, a fifth amplifier and a sixth amplifier; The voltage on the current sampling resistor is input to the non-inverting input terminal of the third amplifier, and the inverting input terminal of the third amplifier is connected to the output terminal of the third amplifier; The middle tap output end of the first chip is connected to the non-inverting input end of the fourth amplifier, the inverting input end of the fourth amplifier is connected to the output end of the fourth amplifier, and the middle tap of the first chip The output voltage is one-thousandth of the voltage output by the positive output terminal of the first chip; The output terminal of the third amplifier is connected to the non-inverting input terminal of the fifth amplifier through the twenty-second resistor, and the output terminal of the fourth amplifier is connected to the inverting input terminal of the fifth amplifier through the twenty-ninth resistor end; The output terminal of the fifth amplifier is connected to the non-inverting input terminal of the sixth amplifier, and the inverting input terminal of the sixth amplifier is connected to the output terminal of the sixth amplifier; The output end of the sixth amplifier is connected to a voltage ammeter. 5. The vacuum detection device of the accelerating tube of the linear accelerator according to claim 4, further comprising: a chain control circuit; The chain control circuit includes: a seventh comparator, an eighth comparator and an optocoupler; The inverting input terminal of the seventh comparator is connected to the output terminal of the fifth amplifier; the non-inverting input terminal of the seventh comparator is connected to the voltage difference of the first chip; the voltage of the first chip The difference is the difference between the voltage output by the middle tap of the first chip and the voltage output by the negative output terminal of the first chip; The output terminal of the seventh comparator is connected to the inverting input terminal of the eighth comparator, and the non-inverting input terminal of the eighth comparator is connected to the reference voltage; the output terminal of the eighth comparator is connected to the optical The anode of the light-emitting diode of the coupling; the cathode of the light-emitting diode of the optocoupler is grounded; The first output end of the optocoupler is connected to the power supply, and the second output end of the optocoupler is connected to the host computer; The host computer is configured to control the acceleration tube to stop working when judging that the signal output by the second output terminal of the optocoupler is a valid signal. 6. The vacuum detection device for the accelerating tube of the linear accelerator according to claim 5, further comprising: a seventh amplifier; The seventh amplifier is used to amplify the voltage difference of the first chip and connect it to the non-inverting input terminal of the seventh comparator. 7. The vacuum detection device of the accelerating tube of the linear accelerator according to claim 2, wherein the filter circuit is a low-pass filter circuit, and the low-pass filter circuit comprises: an eighth resistor, a ninth resistor and a first resistor. Six capacitors; The first end of the eighth resistor is connected to the output end of the first-stage amplifying circuit, and the second end of the eighth resistor is connected to the first end of the ninth resistor; The second end of the ninth resistor is connected to the input end of the second-stage amplifying circuit; The second end of the eighth resistor is grounded through the sixth capacitor. 8. The vacuum detection device of the accelerating tube of the linear accelerator according to claim 2, wherein the first-stage amplifying circuit comprises: a first amplifying chip, a second resistor and a third resistor; The voltage on the current sampling resistor is input to the non-inverting input terminal of the first amplifying chip, the inverting input terminal of the first amplifying chip is grounded through the second resistor; the output terminal of the first amplifying chip is grounded through the third The resistor is connected to the inverting input terminal of the first amplifier chip. 9. The vacuum detection device of the accelerating tube of the linear accelerator according to claim 2, wherein the filter circuit is a low-pass filter circuit; The low-pass filter circuit includes: an eighth resistor, a ninth resistor and a sixth capacitor; The first end of the eighth resistor is connected to the output end of the first-stage amplifying circuit, and the second end of the eighth resistor is connected to the first end of the ninth resistor; The second end of the ninth resistor is connected to the input end of the second-stage amplifying circuit; The second end of the eighth resistor is grounded through the sixth capacitor.