Accelerator beam measurement and diagnosis control system

Abstract

The invention discloses a control system for accelerator beam measurement and diagnosis, and belongs to the field of accelerator beams. The system is constructed on the basis of an EPICS architecture, the EPICS is mainly composed of three parts, namely a device control level (Devices), an input and output controller (IOC) server and an operator interface (OPI), and a typical distributed control architecture is formed. The system equipment control level comprises a series of beam diagnosis elements used for observing and monitoring the beam state, corresponding independent electronics and control software and used for measuring the beam intensity, emittance, position and energy parameters of the accelerator. The whole control system is constructed based on an EPICS architecture, has high stability and reliability, and is suitable for long-time continuous operation; good flexibility and expansibility are achieved, and the system upgrading and maintaining efficiency is improved; and various interfaces and equipment are supported, so that a user can control conveniently.

Description

Technical Field

[0001] The invention discloses a control system for measuring and diagnosing an accelerator beam, and belongs to the field of accelerator beam. Background Art

[0002] The primary task of the beam transport system is to distribute the beam generated by the accelerator to multiple treatment rooms with precisely controlled parameters. The energy is precisely adjusted according to the treatment requirements of different tumors; the beam intensity is regulated according to the dose requirements of different treatment plans; the stability and uniformity of the beam during transmission are ensured through the management of phase space distribution and continuously adjustable collimators. Accelerator beam measurement and diagnosis measures and diagnoses the beam intensity, beam position, emittance and beam intensity through beam diagnostic elements and electronic systems to ensure that the beam transport system can accurately control the beam parameters.

[0003] In order to ensure that the beam transport system can accurately control the beam parameters, it is necessary to develop an accelerator beam and diagnostic system that can measure and diagnose the beam intensity, beam position, emittance and beam current. Summary of the invention

[0004] The purpose of the present invention is to solve the above problems and provide a control system for accelerator beam measurement and diagnosis, which aims to ensure that the beam transport system can accurately control the beam parameters and realize the measurement and diagnosis of beam intensity, beam position, emittance and beam current.

[0005] The present invention achieves the above-mentioned purpose through the following technical solutions: a control system for accelerator beam measurement and diagnosis, including three parts: device control level (Devices), input output controller IOC (Input Output Controller) and operator interface OPI (Operator Interface). It is characterized in that the device control level includes beam intensity detector ACCT, beam position detector BPM (Beam Position Monitor) electronics, emitter and supporting acquisition system, Faraday cup and supporting acquisition system and beam scraping ring; the input output controller IOC is the core part of EPICS, including distributed real-time database and device driver; the operator interface OPI includes real-time data, status information, alarm information; The beam intensity detector ACCT is used to measure the intensity of the pulse beam online in real time, and is a beam non-truncation device, and sends the measurement information to the host computer to display the waveform of the pulse beam intensity; The beam position detector BPM electronics is used to measure the electromagnetic field of the beam, and calculate the beam position information based on the different amplitudes of the electromagnetic field coupled by different electrodes. The beam energy is further calculated based on the provided beam position information and phase information, and the relative flux and energy of the beam are indirectly measured. The BPM electronics completes the monitoring of the beam position and uploads it to the host computer through communication. The host computer displays the current beam position and calculates the energy of the beam based on the phase difference of the signal between the two BPMs; The Faraday cup is used for beam current intensity measurement and as a beam junk target, and belongs to the truncated beam current intensity measurement. The output signal is current, which is connected to the beam measurement electronics system after current / voltage conversion (I / V conversion). The Faraday cup accesses the input / output controller IOC through Ethernet and exchanges data; The emitter is used to measure the emittance of the beam, and the emitter adopts a double-slit structure. The double-slit emitter mainly consists of a front slit, a rear slit and a Faraday cup in the X and Y directions. The front slit is a position sample to determine the position of the beam; the rear slit is an angle sample to determine the angle of the beam; the Faraday cup receives the beam size and determines the density of the beam at a certain position and angle. By scanning the rear slit at different front slit positions, the beam density at different positions and angles is determined, and the phase diagram and density distribution of the beam in the phase space are determined to obtain the emittance of the beam. The emitter electronics sends the full-process flow intensity sampling and the corresponding probe position results to the host computer through communication, and the host computer completes the calculation of the beam emittance.

[0006] Preferably, the beam intensity detector ACCT has no vacuum flange and is installed outside the vacuum pipe of the beam line where pulse beam intensity measurement is required, and is used to measure the beam intensity of the DC beam without truncation.

[0007] Preferably, the detector BPM of the beam position is composed of a probe and electronics for obtaining precise information. The detector BPM of the beam position is of button type, which improves the output signal power and obtains better transmission sensitivity. The detector BPM of the beam position uses electrodes insulated from pipes to measure the image current signal generated when the particle beam passes through. Due to the proximity effect, the closer the beam is to the electrode, the greater the image current generated, so a pair of electrode signals contain the position information of the beam in this direction. The current signal is transmitted to the electronic circuit via the coaxial line for amplification, collection and post-processing calculation to obtain the beam position and phase information.

[0008] Preferably, the emitter and the supporting collection system adopt the double-slit method for measurement. The emitter and the supporting collection system are connected to a precise stepper motor motion control system and a grating ruler, a digital display, and electronic data reading and control. In addition, in order to measure clearer beam information, bias voltage is used, and water cooling is used to protect the equipment.

[0009] Preferably, the Faraday cage and the matching collection system are an interception beam diagnostic device used to measure the beam current. Its structure is a fully interception collection target. When the beam hits the target, it is intercepted and collected by the target, and the charge carried by the beam is deposited on the target, and the beam current is measured after electronic processing.

[0010] Preferably, the beam scraping ring adopts a four-petal splicing method, so that the internal aperture is adjustable and a cooling water channel is provided inside. By leading the signal of the four-petal beam scraping ring through a wire, the beam intensity bombarding the beam scraping ring can be measured.

[0011] Preferably, the supporting acquisition system includes a beam measurement front-end module and a self-developed multi-channel acquisition board, the beam measurement front-end module converts the pulse beam through IV conversion, and the self-developed multi-channel acquisition board collects the beam measurement front-end output signal.

[0012] The IV conversion amplifies the weak current signal into a voltage signal of mV or even V level through a high-precision large resistor, and realizes weak current measurement by measuring the voltage value.

[0013] The self-developed multi-channel acquisition board is designed with 8 channels, the sampling bandwidth is greater than 650MHz, and 8 pieces of ADI's 125MHz sampling rate AD chips AD9265 are used. The external interface of the self-developed multi-channel acquisition board is used as a trigger input and output interface to receive external trigger signals for synchronous acquisition and data storage. The interlock output interface is used to detect the current beam intensity signal and compare it with the internal set value. When it exceeds the set value threshold, a level signal is output to perform a protection action.

[0014] Preferably, the electronics adopts digital I / Q digital down-conversion technology, the high-frequency front end amplifies the input signal, and then inputs it into the ADC, and after AD sampling, the amplitude and phase data are obtained through digital I / Q down-conversion for calculating the beam position and phase. The software algorithm is implemented in the FPGA chip of the digital processing circuit.

[0015] Preferably, the emitter electronics adopts a standard CPCI chassis design, and the expanded IO control card completes the control of the emitter motor and the reception of the grating ruler position feedback and limit signal. The self-developed beam measurement front-end module completes the IV conversion of the pulse beam, and the self-developed multi-channel acquisition board completes the acquisition of the beam measurement front-end output signal.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The control system for accelerator beam measurement and diagnosis disclosed in the present application is characterized in that the control system is constructed based on the EPICS architecture, and the control system includes a device control level, an input and output controller IOC server and an operator interface OPI. The device control level includes a beam intensity detector ACCT, a beam position detector BPM, an emitter and a supporting acquisition system, a Faraday cup and a supporting acquisition system and a beam scraping ring. The device control level is used to measure the accelerator beam intensity, emittance, position and energy. The IOC server includes a distributed real-time database and a device driver. The IOC server stores the device real data, parameters and status information in a database and provides read and write access to these data. The device driver is used to communicate and control the device. The operator interface OPI is used to monitor and control the device, display real-time data, status information, and alarm information through a graphical interface, and allow the operator to control the device and set parameters. The entire control system is constructed based on the EPICS architecture, has high stability and reliability, and is suitable for long-term continuous operation; has good flexibility and scalability, improves the efficiency of system upgrades and maintenance; and supports a variety of interfaces and devices, which is convenient for users to control. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A control structure diagram of a control system for accelerator beam measurement and diagnosis according to the present invention; Figure 2 A schematic diagram of the BCT structure of a control system for accelerator beam measurement and diagnosis according to the present invention; Figure 3 The BPM principle diagram of a control system for accelerator beam measurement and diagnosis of the present invention; Figure 4 The working principle diagram of the double-slit emittance meter of the control system for accelerator beam measurement and diagnosis of the present invention; Figure 5 This is a scanning flow chart of an emitter instrument of a control system for accelerator beam measurement and diagnosis of the present invention; Figure 6 This is a principle block diagram of a Faraday bucket beam measurement front end of a control system for accelerator beam measurement and diagnosis of the present invention; Figure 7 The present invention is a block diagram of the principle of a beam scraping ring beam measurement front end of a control system for accelerator beam measurement and diagnosis. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0019] like Figure 1 As shown in the figure, a control structure diagram of a control system for accelerator beam measurement and diagnosis is constructed based on EPICS, and is composed of a device control level, an input-output controller IOC, and an operator interface OPI. The device control level includes ACCT, BPM, emitter, Faraday cup, and beam scraper ring, which mainly realizes the detection function of the beam state, and sends the beam state to the input-output controller IOC, and interacts with OPI through the CA protocol to realize the real-time data update, status information display, and alarm information prompt functions of the OPI interface. The entire control system is constructed based on the EPICS architecture, which has high stability and reliability and is suitable for long-term continuous operation; it has good flexibility and scalability, which improves the efficiency of system upgrades and maintenance; and it supports a variety of interfaces and devices for user-friendly control.

[0020] like Figure 2 As shown in the figure, a schematic diagram of the BCT structure of a control system for accelerator beam current measurement and diagnosis. The beam current intensity is usually measured using a beam current transformer (Beam Current Tranformer). In this device, the beam current can be considered as the primary, single-turn winding of a transformer, and its equivalent current is "converted" to the secondary winding output. Changing the current in the primary coil changes the magnetic flux generated, and the changed magnetic flux generates current in the secondary coil. BCT relies on a toroidal coil made of ferromagnetic material to capture the magnetic field and pass it through a load resistor. of n The beam current through the toroidal coil The current is generated in the secondary n-turn winding This current is converted into an output voltage The BCT transfer impedance, which determines the output voltage for a given beam current, can be defined as .

[0021] Each BCT has a limited bandwidth, characterized by a low cutoff frequency and a high cutoff frequency. and . Usually, they are selected based on the spectral content of the beam to minimize distortion of the beam pulse. The low cutoff frequency results from the reduction of the impedance of the secondary winding at low frequencies. The secondary winding inductance is given by Given, where is the toroidal inductance constant, in nH / t 2 (t represents the number of turns). Depends on the toroidal coil material and its geometry, especially the length to cross-section ratio. At, the inductive reactance of the secondary power supply is:

[0022] The fact that the BCT has a low frequency cutoff means that the output signal will have no DC component, which will cause signal distortion. For long pulses with low duty cycles (such as the beam of a linear accelerator), the distortion is called "droop". The amount of droop at the end of the pulse depends on the pulse length. With time constant When When , its dependence is linear. Short beams will exhibit a phenomenon known as "baseline shift", where the steady-state integral of the BCT output signal is zero. Therefore, special compensation techniques are usually required to restore the missing DC response, called "baseline restoration" techniques, which are solved by digital circuits.

[0023] If it is below the low cutoff frequency The BCT frequency characteristic is defined by the first-order high-pass of the secondary winding inductance and its load, which can be compensated by analog circuits. This can be achieved using an amplifier with greater gain for these low frequencies. Such a circuit can be completed with an operational amplifier and feedback circuit. For low frequencies, its gain is , and for high frequencies, the gain is ,in for and The parallel resistance of The capacitor C is selected to achieve a flat overall frequency response. The price paid for this higher low-frequency gain of the amplifier is a degradation in the noise performance of the compensated frequency band.

[0024] Selecting ACCT without vacuum flange and only ensuring that there is an insulating gap on the vacuum pipe can also achieve accurate measurement and be used to measure the beam current intensity of the DC beam without truncation.

[0025] like Figure 3As shown in the figure, a BPM schematic diagram of a control system for accelerator beam measurement and diagnosis. When the particle beam moves in the pipe, an image current is generated on the inner wall of the pipe, and its density distribution is similar to the particle beam density distribution. The image current signal generated when the particle beam passes through can be measured by using electrodes insulated from the pipe. Due to the proximity effect, the closer the beam is to the electrode, the greater the image current generated. Therefore, a pair of electrode signals contain the position information of the beam in this direction. The current signal is transmitted to the electronic circuit via the coaxial line for amplification, collection and post-processing calculation to obtain the beam position and phase information.

[0026] The parasitic capacitance between the electrode and the pipe is C. When the beam length is much longer than the electrode length, the BPM output voltage signal when the beam is at the center is:

[0027] In the formula, is the electrode angle; l is the electrode length; v is the particle velocity; is the RF angular frequency; is the mirror current; is the characteristic impedance.

[0028] The position signal is further normalized to make it independent of the signal amplitude. The difference ratio and signal processing method give the normalized electronic position signal of the horizontal position x as:

[0029] The normalized electronics signal for the vertical position y can also be calculated:

[0030] It can be seen from the formula that the larger the wire displacement from the center of the BPM, the more significant the nonlinearity. Near the center of the beam pipe, the difference ratio and the beam position are linearly related, where It is called position sensitivity, and further obtains BPM position resolution The relationship with sensitivity and signal amplitude is:

[0031] in is the signal-to-noise ratio, is the electronic noise, The signal power is determined by the circuit design and process. Therefore, in order to achieve high measurement resolution, the BPM signal amplitude and sensitivity should be increased as much as possible, while reducing electronic noise and improving the signal-to-noise ratio. The BPM electrode resolution determines its ability to measure small changes in beam position.

[0032] According to the BPM electrode output signal amplitude and is directly proportional to The output signal amplitude is the largest when . The three-dimensional electromagnetic simulation software CST Particle Studio is used to simulate the output signal of BPM when the beam passes through, and the BPM structure is optimized.

[0033] The BPM calibration test bench consists of an XY translation mechanism, a rotation mechanism, and a wire fine-tuning mechanism. The translation mechanism moves with a thin wire (simulated beam) to simulate the position of the beam at different positions. The rotation mechanism provides rotation for the BPM detector for the measurement of various parameters. The wire fine-tuning mechanism is composed of three sets of micro-feed components. The wire can be translated in the X, Y, and Z directions to achieve vertical calibration of the wire. The direction of the wire is parallel to the axis of the turntable and is calibrated using a theodolite.

[0034] The main sources of noise are thermal noise and the noise coefficient of electronic circuits. The thermal noise power can be expressed as:

[0035] Where k is the Boltzmann constant, 1.38, in J / K. T is the absolute temperature, in K. B is the bandwidth, in Hz. The thermal noise power at room temperature of 300K is -173.83dBm / Hz = -113.83dBm / MHz.

[0036] The electrode capacitance depends on the electrode radius, gap distance and electrode thickness. The detailed calculation formula is as follows:

[0037]

[0038] Where I is the beam current intensity, The characteristic impedance is 50Ω. The electrode radius is b, r is the probe radius, c is the speed of light, The dielectric constant of vacuum, d is the electrode thickness, w is the electrode gap, and L represents the electrode plate thickness. The capacitance is calculated It is 0.305pF.

[0039] Without considering the influence of electronic noise, the best resolution that can be achieved depends entirely on the influence of thermal noise. The resolution calculated in this case is called BPM intrinsic resolution or intrinsic resolution .

[0040] like Figure 4As shown in FIG. 1 , a double-slit emittance meter of a control system for accelerator beam measurement and diagnosis works as a principle diagram. For proton beams and negative hydrogen ion beams with lower energy, when the energy is lower, beam interception methods are generally used, such as the slit method, the slit wire method, and the Allison instrument. These measurement methods directly measure the distribution of the beam position x and the divergence angle x´, as described in the emittance definition. A commonly used method in proton or ion linear accelerators is the slit-grid device. The slit method can reduce the collective effect of the space charge-dominated beam that is so large that the measurement is invalid.

[0041] The movement of the slit corresponds to the information of different positions x; keeping x stationary, the secondary electron emission (SEM) grid is moved to obtain all emission angle x' information at the corresponding position x, and the SEM grid obtains the beam intensity ρ(x, x') information at the corresponding phase space position. The double-slit measurement method is similar to this, except that the SEM grid is replaced with a slit device similar to the measurement position x, and a Faraday bucket is installed behind the second slit to obtain the received beam signal. The advantages and disadvantages of the two are reflected in the following: the double slit requires more moving operations (the second slit), while the slit-grid requires more output signal loops. This control system uses a double-slit emittance meter to measure the beam transverse emittance.

[0042] like Figure 5 As shown, an emitter scanning flow chart of a control system for accelerator beam measurement and diagnosis is provided. According to the working principle of the emitter, the position information of the front and rear slits and the corresponding flux information measured by the Faraday bucket are directly obtained during one emitter measurement process.

[0043] For the data matrix directly obtained by the emitter scanning, all the second slit position data x must first be converted into the particle divergence angle X´:

[0044] Where L is the horizontal distance between the front and rear slits (mm), and the divergence angle X' is in mrad. In this way, the beam emittance ε can be calculated by the statistical moment of the two-dimensional distribution ρ(X, X').

[0045] In practice, the root mean square (rms) value of emittance is usually used to describe the beam quality, which can be expressed as follows:

[0046] in:

[0047]

[0048]

[0049] In the formula and are their respective expected values.

[0050] It is more common to use the Twiss parameter (Courant Snyder function) to describe the emittance, which is the emittance normalized phase ellipse matrix. For RMS emittance:

[0051] The Twiss matrix T is expressed as:

[0052] visible .

[0053] During beam transmission, the elliptical phase area with the (X, X') coordinate axis is conserved only when the particle energy remains unchanged. If the particle energy changes, the phase area is inversely proportional to the square of the particle energy, that is, as the particle accelerates, the phase area will become smaller, but the product of the phase area and the particle momentum will remain unchanged. In order to compare the emittance of particle beams with different energies, the normalized emittance is introduced :

[0054] Where β and γ are the relativistic velocity and the Lorentz factor, respectively, which are different from the Twiss parameter. and beam energy Available All calculation results, beam phase diagrams, and spatial distribution diagrams are presented together.

[0055] like Figure 6 As shown in the figure, a Faraday bucket beam measurement front-end principle block diagram of a control system for accelerator beam measurement and diagnosis uses a high-precision non-inductive low-temperature drift wafer resistor to convert the current signal into a voltage signal. A high-speed differential amplifier is connected to complete long-distance common-mode noise suppression. The front-end amplifier needs to collect a large current signal and meet the 100ns pulse beam measurement. The zero calibration circuit completes the calibration of the zero drift caused by the bias voltage and power supply imbalance. The beam measurement front-end module is placed nearby with a low-ripple power supply.

[0056] The control system uses a MHz AD acquisition board to digitally quantify the signal after the front-end amplifier IV conversion. Each acquisition board has 8 channels and the sampling width is greater than 650MHz. The main control chip is used to receive external signals for synchronous acquisition and data storage, and transmit the stored data to the IOC server via Ethernet at the falling edge of the start signal. Through the set value, when the detected beam intensity signal exceeds the set value valve, the main control chip outputs a level signal for protection action.

[0057] like Figure 7As shown in the figure, a beam scraping ring beam measurement front-end principle block diagram of a control system for accelerator beam measurement and diagnosis is used. A high-speed, low-noise differential amplifier is selected, and the zero calibration circuit completes the calibration of the zero drift caused by the bias voltage and power supply imbalance. In order to reduce the interference of the beam signal and the noise caused by the power supply ripple, the beam measurement front-end module is placed nearby with a low-ripple power supply. The signal after the front-end amplifier IV conversion is digitally quantized, and a MHzAD acquisition board is used. Each acquisition board has 8 channels and the sampling width is greater than 650MHz.

[0058] In order to safely absorb the beam and ensure that the DUMP will not be melted by the beam, the beam needs to be expanded through the quadrupole iron to flatten the power density of the beam and reduce the maximum temperature of the DUMP. After the beam is expanded, the edge particles in the outer circle will exceed the receiving range of the DUMP. In order to properly handle these halo particles in the outer circle, a special beam scraper is needed to safely absorb them. The use of a beam scraper can control the edge particles that are inevitably lost before the DUMP after beam expansion at the beam scraper, achieve safe and controllable beam loss, and greatly reduce the heat and radiation activation effects caused by beam loss, thereby protecting the sealing flange of the upstream beam line of the DUMP and reducing the activation dose of the stainless steel beam pipeline. In addition, after the beam scraper ring is insulated, it can be used to detect halo particles. Once the beam is eccentric or the beam spot is too large, resulting in excessive beam particles directly bombarding the beam scraper, the current signal measured by the beam scraper ring can be given a threshold protection to cut off the beam, avoiding damage to the flange in front of the DUMP, damage to the beam scraper ring or damage to the beam line due to beam eccentricity or excessive beam spot.

[0059] The mechanical structure of the beam scraper adopts a four-petal splicing method, which makes the internal aperture adjustable and has a cooling water channel. By leading the signal of the four-petal beam scraper ring through the wire, the beam current intensity bombarding the beam scraper ring can be measured.

[0060] The beam scraping ring electronics adopts the standard CPCI chassis design, the self-developed beam measurement front-end module completes the IV conversion of the pulse beam, and the self-developed multi-channel acquisition board completes the acquisition of the beam measurement front-end output signal.

[0061] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0062] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A control system for accelerator beam measurement and diagnosis, which is built based on the EPICS architecture and includes three parts: device control level (Devices), input and output controller IOC (Input Output Controller) and operator interface OPI (Operator Interface); the device control level includes ACCT, BPM, emitter, Faraday cup, beam scraper ring, supporting acquisition system and supporting beam measurement electronics system; the input and output controller IOC is the core part of EPICS, including distributed real-time database and device driver; the operator interface OPI includes real-time data, status information and alarm information; Features: The beam measurement electronics system adopts digital I / Q digital down-conversion technology, and the beam measurement electronics system calculates the position information, phase information, current intensity information and energy information of the beam according to the information of the acquisition system of each monitoring device; The acquisition system measures the beam current information in real time, sends the measurement information to the matching beam measurement electronics system, processes the matching beam measurement electronics system, and transmits the calculation results to the host computer through Ethernet to display the waveform of the pulse beam current intensity.

2. The control system for accelerator beam measurement and diagnosis according to claim 1, characterized in that: The BPM is composed of a probe and a matching beam measurement electronics system. The BPM adopts a button-type design. The BPM uses electrodes insulated from pipelines to measure the image current signal generated when a particle beam passes through. The current signal is passed through the matching beam measurement electronics system to obtain beam position and phase information.

3. The control system for accelerator beam measurement and diagnosis according to claim 1, characterized in that: The emittance meter is used for measuring beam emittance, and adopts a double-slit structure consisting of a front slit, a rear slit and a Faraday cup in the X and Y directions respectively. By scanning the rear slit at different front slit positions, the beam density at different positions and angles is determined, and the phase diagram and density distribution of the beam in the phase space are determined to obtain the beam emittance; the beam measurement electronics system sends the full-process flow intensity sampling and the corresponding probe position results to the input-output controller IOC, and the input-output controller IOC completes the calculation of the beam emittance.

4. The control system for accelerator beam measurement and diagnosis according to claim 1, characterized in that: The Faraday cup measures the beam current intensity by a full-blocking method. When the beam hits the target, it is intercepted and collected by the target, and the charge carried by the beam is deposited on the target. The Faraday cup outputs current, which is connected to the beam measurement electronics system after current / voltage conversion (I / V conversion). The beam current intensity is measured after being processed by the matching beam measurement electronics system.

5. The control system for accelerator beam measurement and diagnosis according to claim 1, characterized in that: The acquisition system includes a beam measurement front-end module and a self-developed multi-channel acquisition board. The beam measurement front-end module converts the pulse beam through IV conversion, and the self-developed multi-channel acquisition board collects the output signal of the beam measurement front-end. The IV conversion amplifies the weak current signal into a voltage signal of mV or even V level through a high-precision large resistor, and realizes weak current measurement by measuring the voltage value; The self-developed multi-channel acquisition board is designed with 8 channels, the sampling bandwidth is greater than 650MHz, and 8 pieces of ADI's 125MHz sampling rate AD chips AD9265 are used. The external interface of the self-developed multi-channel acquisition board is used as a trigger input and output interface to receive external trigger signals for synchronous acquisition and data storage; the interlock output interface is used to detect the current beam intensity signal and compare it with the internal set value. When it exceeds the set value threshold, a level signal is output to perform a protection action.

6. The control system for accelerator beam measurement and diagnosis according to claim 1, characterized in that: The beam measurement electronics system adopts digital I / Q digital down-conversion technology. The input signal is amplified by a high-frequency front end and then input into the ADC. After AD sampling, the amplitude and phase data are obtained through digital I / Q down-conversion. The beam position and phase are calculated based on the obtained amplitude and phase data.

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