Non-blocking beam three-dimensional profile measurement device and measurement method thereof

Abstract

The present application relates to the technical field of particle detection, and provides a non-blocking beam three-dimensional profile measuring device and a measuring method thereof, wherein the internal structure of a measuring main body has a first chamber and a second chamber, a first slit is arranged between the first chamber and the second chamber, and a second slit is arranged on the bottom wall of the second chamber; a beam inlet channel and a beam outlet channel are arranged in the measuring main body in a penetrating manner, and the beam inlet channel and the beam outlet channel are both communicated with the first chamber; an electrostatic magnetic field assembly is arranged in the first chamber; a radio frequency deflection assembly is arranged in the second chamber, and the radio frequency deflection assembly forms a radio frequency electric field; a beam profile measuring component is used for multiplying and amplifying signal electrons, and the signal electrons are captured by an imaging detector after electric-optical conversion, so that the beam profile is measured; a beam bunch length measuring component is arranged on the measuring main body and located below the position of the second slit, and is used for multiplying and amplifying signal electrons and I-V conversion, and cooperates with radio frequency power sweep phase to realize beam bunch length measurement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of particle detection, and in particular to a non-blocking beam three-dimensional profile measurement device and a measurement method thereof. BACKGROUND

[0002] With the rapid development of high-power ion accelerators and the batch construction demand of small-sized accelerators (such as medical cancer treatment accelerators), the accurate measurement of beam three-dimensional distribution (transverse two-dimensional profile and longitudinal bunch length) has become the core technology for stable operation, parameter matching upgrade and performance optimization of the accelerator. The transverse profile of the beam is the basis for diagnosing key parameters such as emittance, operating point, dispersion and chromaticity, and directly affects the transverse cooling, injection matching and machine upgrade effect. The longitudinal bunch length is the core basis for high-frequency trapping, variable-harmonic energy acceleration and longitudinal emittance reconstruction, and is crucial to the acceleration efficiency and beam quality. Therefore, developing a three-dimensional beam measurement technology with high precision and high reliability is an inevitable choice to meet the complex operation requirements of high-power accelerators and the fine control of small-sized accelerators.

[0003] In the prior art, beam three-dimensional measurement mainly relies on probe technology, which can be divided into two types: intercepting type and non-intercepting type.

[0004] For transverse profile measurement, although the intercepting probe (such as wire scanning device, fluorescent target) has strong signal and simple structure, its physical intercepting characteristics will cause beam loss and pollution, and cannot be applied to high-power scenarios. The non-intercepting probe (such as residual gas ionization probe, beam-induced fluorescence probe) avoids beam interference, but the residual gas ionization probe can only measure the profile projection in a single direction, and multiple sets are needed to measure two-dimensional profile information, while the beam-induced fluorescence probe has weak signal and is only suitable for low-energy sections with high air pressure, or requires complex differential pumping / gas curtain design to enhance the signal, which greatly limits its application scenarios.

[0005] For longitudinal bunch length measurement, the blocking probe (such as fast Faraday cup, bunch shape probe) has high bandwidth, but it cannot be used for high-power machines due to direct interception of the beam. The non-blocking probe (such as commercial magnetic ring, wall current probe) avoids blocking the beam, but has problems such as low bandwidth of about 1 GHz and high price, and the Faraday cup or wall current probe based on electromagnetic induction will cause the result to be broadened due to the transverse electromagnetic mode field distribution of the bunch itself in low-energy beam measurement, which cannot meet the high-precision requirement. SUMMARY

[0006] The application provides a non-blocking beam three-dimensional profile measurement device and a measurement method thereof, to solve at least one of the technical defects in the prior art, the measurement body only guides the motion of secondary electrons through electrostatic magnetic field, the beam itself does not physically contact the probe, the beam loss and the risk of thermal damage of the traditional intercepting probe are avoided, continuous operation under high-power beam is realized, and high-precision measurement of the non-intercepting three-dimensional beam profile is realized.

[0007] The first aspect of the application provides a non-blocking beam three-dimensional profile measurement device, comprising:

[0008] A measurement body is internally structured with a first chamber and a second chamber, a first slit is arranged between the first chamber and the second chamber, and a second slit is arranged on the bottom wall of the second chamber; a beam inlet channel and a beam outlet channel are arranged in the measurement body, and the beam inlet channel and the beam outlet channel are both in communication with the first chamber;

[0009] An electrostatic magnetic field assembly is arranged in the first chamber, the electrostatic magnetic field assembly forms an electrostatic magnetic field, and the electrostatic magnetic field is used to drive signal electrons generated by ionization of a beam and residual gas to pass through the first slit and move to the second chamber and a detection end;

[0010] A radio frequency deflection assembly is arranged in the second chamber, the radio frequency deflection assembly can form an electrostatic field or a radio frequency electric field according to different pressurization modes, the electrostatic field is used to perform electrostatic field scanning on the electrons to realize two-dimensional profile measurement, and the radio frequency electric field is used to perform radio frequency alternating field scanning on the electrons to realize beam bunch length measurement;

[0011] A beam profile measurement component is arranged on one side of the radio frequency deflection assembly, is used to multiply and amplify the signal electrons, and is captured by an imaging detector after electro-optical conversion, so as to measure the beam profile;

[0012] A beam bunch length measurement component is arranged on the measurement body and below the position of the second slit, is used to multiply and amplify the signal electrons and perform I-V conversion, and cooperates with radio frequency power phase scanning to realize beam bunch length measurement.

[0013] The non-blocking beam three-dimensional profile measurement device provided by the application comprises:

[0014] An electrode frame body is composed of upper and lower symmetrical plate electrodes and left and right symmetrical strip electrodes, and the upper and lower symmetrical plate electrodes and the left and right symmetrical strip electrodes are both fixed to the inner wall of the first chamber through ceramic support columns;

[0015] High-voltage feedthroughs are welded through flanges of the measuring body, and are connected with high-voltage source plug-in outside the vacuum, and are connected with the upper and lower symmetrical plate electrodes and the left and right symmetrical strip electrodes through metal electrode strips inside the vacuum.

[0016] The high-voltage feedthroughs have high-voltage transmission capacity for each channel, and each high-voltage feedthrough can independently adjust voltage and transmit voltage to the plate electrodes and the strip electrodes.

[0017] The upper and lower symmetrical plate electrodes adjust the X or Y direction of the electric field through the high-voltage source.

[0018] The left and right symmetrical strip electrodes perform electric field shaping through electrode voltage division, improve the uniformity of the field distribution, and form a required electrostatic field in the first chamber.

[0019] The radio frequency deflection assembly comprises:

[0020] The deflection electrode plate is composed of two symmetrical metal electrode plates, and a high-voltage guide rod is connected to the deflection electrode plate, the high-voltage guide rod is connected to an external direct-current high-voltage source, and the deflection electrode plate is fed with electrostatic high voltage.

[0021] The capacitance coupling feedthrough is inserted into the measuring body and forms a capacitor between the deflection electrode plate and the capacitance coupling feedthrough, and radio frequency power source is fed into the resonant cavity through capacitive coupling.

[0022] The tuning electrode plate has a center axis between the two symmetrical metal electrode plates and forms a capacitor, and the size of the capacitor is changed by insertion and extraction to adjust the frequency of the resonant cavity.

[0023] The tuning motor is connected to the tuning electrode plate and is used to drive the extension and retraction movement of the tuning electrode plate to change the capacitance and adjust the resonant frequency.

[0024] The beam profile measurement component comprises:

[0025] The micro-channel plate is arranged on the side wall of the second chamber, and the inner surface of the micro-channel aperture of the micro-channel plate has an easy electron emission coating for avalanche amplification of secondary electrons.

[0026] The phosphor screen is arranged behind the output of the micro-channel plate and is used to produce fluorescence of a specific wavelength after electron bombardment to realize an electro-optical conversion process.

[0027] The optical imaging system is arranged in the measuring body and is used to collect the fluorescence signal of the phosphor screen and transmit the fluorescence signal to a computer for image processing and data fitting.

[0028] The non-blocking beam three-dimensional profile measurement device provided by the application, the beam profile measurement component further comprises:

[0029] A side plate is fixed on the deflection pole plate and maintains the same potential with the deflection pole plate, and a hollow wire mesh is arranged on the side plate;

[0030] The micro-channel plate is arranged behind the side plate and at the position of the hollow wire mesh, the hollow wire mesh provides an unobstructed transmission channel for the electron beam, and can compensate for the abnormal electric field distribution of the cutout area and reduce the profile measurement error.

[0031] The non-blocking beam three-dimensional profile measurement device provided by the application, the beam group length measurement component comprises:

[0032] A scotch-yoke amplifier is arranged on the measurement main body and below the position of the second slit, and is used for amplifying the residual signal electrons passing through the second slit;

[0033] An I-V conversion module is connected to the output end of the scotch-yoke amplifier, and is used for converting the current signal output by the scotch-yoke amplifier into a voltage, and then the voltage is collected by electronics or observed by an oscilloscope, and the longitudinal beam group distribution is obtained by combining the radio frequency sweep phase data fitting.

[0034] The non-blocking beam three-dimensional profile measurement device provided by the application, the measurement main body comprises:

[0035] A cylindrical main body is provided with flanges at both ends;

[0036] A shielding member is arranged in the middle region of the cylindrical main body, and divides the internal space of the cylindrical main body into the first chamber and the second chamber distributed along the axial direction.

[0037] The second aspect of the application provides a measurement method based on the non-blocking beam three-dimensional profile measurement device, comprising the following steps:

[0038] The secondary electrons generated by ionizing the beam and residual gas under the action of the electrostatic high voltage fed by the electrostatic magnetic field assembly move to the detection end, and enter the radio frequency deflection assembly below through the first slit;

[0039] A direct current negative high voltage and a zero potential are respectively applied between the deflection pole plates of the radio frequency deflection assembly, wherein the left pole plate is applied with -10kV, and the right pole plate is applied with 0V to form a uniform electrostatic field for transverse particle deflection;

[0040] When the secondary electrons driven from the electrostatic magnetic field assembly enter the radio frequency deflection area, the two-dimensional profile measurement can be realized by electrostatic field scanning due to the different positions in the beam cross section and the different kinetic energies of the secondary electrons.

[0041] The second aspect of the application provides a measurement method based on a non-intercepting beam three-dimensional profile measurement device, comprising the following steps:

[0042] In the electrostatic magnetic field assembly, corresponding electrostatic high voltage is fed in, the secondary electrons generated by ionization of the beam and residual gas move towards the detection end and enter the radio frequency deflection assembly below through the first slit;

[0043] An equal DC negative high voltage is applied to the deflection plates of the radio frequency deflection assembly, wherein -10 kV is applied to the left plate and -10 V is applied to the right plate, so as to focus the signal electrons and avoid beam divergence; at the same time, the radio frequency power is input to the deflection plates through capacitive coupling feedthrough, so as to generate an alternating electric field between the deflection plates;

[0044] The alternating electric field changes with time, and the timing of radio frequency power feeding can be adjusted through a phase shifter; when the electron group representing the beam distribution information arrives, the sinusoidal alternating field is exactly zero potential difference, at this time, most of the electrons pass through the deflection plates straightly and obtain a larger current signal, and continue to perform high-precision phase scanning, the electrons will be affected by the deflection field and lost at the second slit, and a gradually weakened current signal is obtained, so that the time distribution of the longitudinal beam group can be converted into the spatial distribution of the signal electrons by scanning, so as to realize the function of high-resolution beam length measurement.

[0045] The non-intercepting beam three-dimensional profile measurement device provided by the application can realize high-precision measurement of the non-intercepting three-dimensional beam profile through the synergistic design of the radio frequency electric field, the beam profile measurement component and the beam length measurement component.

[0046] In the whole measurement process, based on the ionization mechanism of residual gas, the ionization product electrons are used as the working medium, the beam itself does not physically contact the probe, and only the secondary electrons generated by ionization indirectly act, therefore, the embodiment of the application avoids the overheating of the equipment caused by the deposition energy of the blocked and absorbed beam particles of the intercepting probe (such as FFC and WS); the generation and collection of the secondary electrons will not cause secondary particle pollution to the downstream area; the beam length measurement of tens of picoseconds and the profile spatial resolution of hundreds of microns can be realized, and the continuous wave (CW) operation requirement of the accelerator can be met.

[0047] The measurement method of the non-intercepting beam three-dimensional profile measurement device provided by the application can realize a non-intercepting, high-bandwidth and full-energy applicable three-dimensional beam profile measurement method, break through the bottleneck of the prior art, and provide key support for stable operation and performance optimization of high-power accelerators. BRIEF DESCRIPTION OF DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0049] Figure 1 It is a front view of the non-blocking beam three-dimensional profile measurement device provided by the embodiment of the present application.

[0050] Figure 2 It is a side view of the non-blocking beam three-dimensional profile measurement device provided by the embodiment of the present application.

[0051] Figure 3 It is a schematic diagram of the internal structure of the non-blocking beam three-dimensional profile measurement device provided by the embodiment of the present application.

[0052] Figure 4 It is a perspective view of the non-blocking beam three-dimensional profile measurement device provided by the embodiment of the present application.

[0053] Figure 5 It is a schematic diagram of the design principle of the non-blocking beam three-dimensional profile measurement device provided by the embodiment of the present application. Wherein, Fig. (a) is a schematic diagram of the principle of the electrostatic field scanning mode (two-dimensional profile measurement). Fig. (b) is a schematic diagram of the principle of the radio frequency electric field scanning mode (beam length measurement).

[0054] Figure 6 It is an electric field equipotential line distribution diagram under the electrostatic field scanning mode (two-dimensional profile measurement).

[0055] Reference signs:

[0056] 10, measurement main body; 11, cylindrical main body; 12, shielding member; 13, first chamber; 14, second chamber; 15, beam inlet passage; 16, beam outlet passage;

[0057] 20, electrostatic magnetic field assembly; 21, electrode frame body; 211, flat plate electrode; 212, strip-shaped electrode plate; 213, ceramic support column; 22, high-voltage feedthrough;

[0058] 30, radio frequency deflection assembly; 31, deflection electrode plate; 32, high-voltage guide rod; 33, capacitive coupling feedthrough; 34, tuning electrode plate; 35, tuning motor;

[0059] 40, beam profile measurement component; 41, side plate; 42, micro channel plate;

[0060] 50, beam length measurement component; 51, stripline amplifier. DETAILED DESCRIPTION

[0061] So that the objectives, technical solutions and advantages of the present application can be clearer, the technical solutions in the present application will be clearly and completely described below in conjunction with the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0062] In the description of the embodiments of the present application, it should be noted that unless specifically defined and limited, the terms "connected", "connected" should be understood in a broad sense, for example, it can be fixedly connected, or detachably connected, or integrally connected, it can be mechanically connected, or electrically connected, it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0063] In the embodiments of the present application, unless specifically defined and limited, the first feature is "on" or "under" the second feature, which can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0064] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those of ordinary skill in the art can combine and combine the different embodiments or examples described in the present application and the features of the different embodiments or examples without contradiction.

[0065] Figure 1 is the front view of the non-blocking beam three-dimensional profile measurement device provided by the embodiments of the present application. Figure 2 is the side view of the non-blocking beam three-dimensional profile measurement device provided by the embodiments of the present application. Figure 3 is the internal structure schematic diagram of the non-blocking beam three-dimensional profile measurement device provided by the embodiments of the present application. Figure 4Figure 1 is a perspective view of a non-blocking beam three-dimensional profile measurement device according to an embodiment of the present application.

[0066] Referring to Figures 1 to 4 The present application provides a non-blocking beam three-dimensional profile measurement device, which comprises a measurement main body 10, an electrostatic magnetic field assembly 20, a radio frequency deflection assembly 30, a beam profile measurement component 40 and a beam bunch length measurement component 50.

[0067] The measurement main body 10 comprises a cylindrical main body 11 and a shielding member 12. The cylindrical main body 11 is in a hollow cylindrical structure, and the measurement main body 10 is made of non-magnetic stainless steel to avoid interference with the beam magnetic field. The two ends of the cylindrical main body 11 are provided with flanges for connection. The shielding member 12 is arranged in the middle region of the cylindrical main body 11, and divides the internal space of the cylindrical main body 11 into a first chamber 13 and a second chamber 14 distributed along the axial direction. The shielding member 12 is a metal shielding member or an electromagnetic shielding member, and the shape of the shielding member 12 is adapted to the cross section of the cylindrical main body 11, and is sealingly connected with the inner wall of the cylindrical main body 11 to enhance the chamber isolation effect.

[0068] A first slit is arranged between the first chamber 13 and the second chamber 14, i.e. the first slit is arranged on the shielding member 12, and the width of the first slit is smaller than the transverse size of the beam, to ensure the isolation of the electrostatic magnetic field region and the radio frequency deflection region. The bottom wall of the second chamber 14 is provided with a second slit, and the second slit is used for signal output of the radio frequency deflection assembly 30, and the width of the second slit allows the signal electrons to pass through and be screened.

[0069] A beam inlet channel 15 and a beam outlet channel 16 are arranged through the measurement main body 10, and both the beam inlet channel 15 and the beam outlet channel 16 are in communication with the first chamber 13. Both the beam inlet channel 15 and the beam outlet channel 16 are in communication with the accelerator pipe through flanges, and the beam enters the first chamber 13 through the beam inlet channel 15, and then collides with the residual gas Molecular collision ionization generates electron-ion pairs (secondary electrons), and the measurement main body 10 only guides the motion of the secondary electrons by the electrostatic magnetic field, and the beam itself does not physically contact the probe, avoiding the beam loss and thermal damage risk of the traditional intercepting probe (such as FFC and WS).

[0070] The electrostatic magnetic field assembly 20 is arranged in the first chamber 13, and the electrostatic magnetic field assembly 20 forms an electrostatic magnetic field, which is used to drive the electron signals generated by the ionization of the beam and the residual gas to pass through the first slit and move towards the second chamber and the detection end. That is, the core function of the electrostatic magnetic field assembly 20 is to provide driving force for the directional motion of the secondary electrons (signal particles) generated by the ionization of the beam and the residual gas, to ensure that they can effectively reach the subsequent measurement region.

[0071] The radio frequency deflection assembly 30 is arranged in the second chamber 14, and can form an electrostatic field or a radio frequency electric field according to different pressurization modes, the electrostatic field is used for electrostatic field scanning of the electrons to realize two-dimensional profile measurement, and the radio frequency electric field is used for radio frequency alternating field scanning of the electrons to realize bunch length measurement.

[0072] The beam profile measurement component 40 is arranged on one side of the radio frequency deflection assembly 30, is used for multiplying amplification of the signal electrons, and is captured by an imaging detector after electro-optical conversion, so as to measure the beam profile.

[0073] Since the initial intensity of the secondary signal electrons is extremely weak (may be only a few to tens of electrons), the secondary signal electrons need to be effectively captured by the imaging detector through two-stage amplification and conversion, therefore, the beam profile measurement component 40 includes a micro channel plate 42 (MCP), a phosphor screen and the like, and is used for converting the deflected signal electrons into optical signals.

[0074] Specifically, the secondary electrons bombard the inner wall of the micro channel of the input surface of the MCP, trigger secondary electron avalanche multiplication, and output a large number of electrons; after the electrons bombard the phosphor screen (such as a phosphor material) behind the output surface of the MCP, the screen material triggers a process to emit fluorescence, which is converted into a visible light signal (the fluorescence intensity is proportional to the number of electrons), and is used for multiplying amplification and two-dimensional profile measurement of the collected electrons. The fluorescence intensity distribution reflects the lateral density of the signal electrons, and also reflects the two-dimensional profile distribution of the primary beam.

[0075] The bunch length measurement component 50 is arranged on the measurement body 10 and is located below the position of the second slit, is used for multiplying amplification and I-V conversion of the signal electrons, and is matched with radio frequency power phase scanning to realize bunch length measurement.

[0076] The non-blocking type beam three-dimensional profile measurement device provided by the embodiment of the application is used in the following manner: in the transmission process of the high-energy beam (such as an ion beam), the high-energy beam collides with trace gas molecules (such as ) remaining in the pipeline, a large number of electron-ion pairs (secondary electrons) are generated through the Coulomb collision ionization effect. The electrostatic magnetic field assembly 20 generates a uniform or gradient distribution electrostatic force field in the first chamber 13, the secondary electrons are accelerated and directionally move under the action of the electrostatic force, and migrate along a preset path to the direction of the radio frequency deflection assembly 30, such as perpendicular to the beam transmission direction, to avoid signal loss caused by thermal diffusion motion or space charge effect. The electrons entering the second chamber 14 are measured by the beam profile measurement component 40, and the electrons entering the second chamber 14 are multiplied and amplified by the bunch length measurement component 50 and are used for assisting to realize bunch length measurement.

[0077] It can be understood that the non-blocking beam three-dimensional profile measurement device provided by the embodiment of the application measures the main body 10 only by guiding the motion of secondary electrons by electrostatic magnetic field, the beam itself does not physically contact the probe, avoids the beam loss and the risk of thermal damage of the traditional intercepting probe, and can continuously operate under high-power beam. And through the coordinated design of the particle trajectory control by the radio frequency electric field, the beam profile measurement component 40 and the beam bunch length measurement component 50, the high-precision measurement of the non-intercepting three-dimensional beam profile is realized.

[0078] During the whole measurement process, based on the ionization mechanism of residual gas, the ionization product electrons are used as the working medium, the beam itself does not physically contact the probe, and only the secondary electrons generated by ionization indirectly act, therefore, the embodiment of the application avoids the overheating of the equipment caused by the deposition energy of the blocked and absorbed beam particles of the intercepting probe (such as FFC and WS); the generation and collection of secondary electrons will not cause secondary particle pollution to the downstream area; the beam bunch length measurement of tens of picoseconds and the profile spatial resolution of hundreds of microns can be realized, and the continuous wave (CW) operation requirement of the accelerator is met.

[0079] Specifically, the spatial resolution of the electrostatic magnetic field guidance and the radio frequency electrostatic field scanning reaches 0.1 mm, which is determined by the deflection plate 31 spacing, the electron drift speed, the optical acquisition system and the like.

[0080] Continuing to refer to Figure 3 In some embodiments of the application, the electrostatic magnetic field assembly 20 includes an electrode frame body 21 and a high-voltage feedthrough 22, the electrode frame body 21 is composed of upper and lower symmetrical plate electrodes 211 and left and right symmetrical strip electrodes 212, the upper and lower symmetrical plate electrodes 211 (assuming the horizontal direction, along the X-Z plane) and the left and right symmetrical strip electrodes 212 (assuming the vertical direction, along the X-Y plane) are both fixed to the inner wall of the first chamber 13 through ceramic support columns 213. Among them, the electrode plate material is usually selected from easily processed metals and stainless steel, and the surface needs to be polished to reduce the edge electric field distortion or sharp tip discharge.

[0081] The function of the ceramic support column 213 is to isolate the electrode plate from the chamber (to avoid the short circuit of the electrode plate and the ground) and to support the mechanical structure of the electrode plate. Among them, the ceramic support column 213 needs to select a high dielectric strength material (such as alumina ceramic) to ensure the insulation reliability under high voltage.

[0082] Since the first chamber 13 is a closed metal cavity (such as stainless steel) for accommodating the electrode frame body 21 and the beam to be measured. The flange (mechanical interface) of the measurement main body 10 needs to be sealingly connected (such as welding or bolt fastening) with the chamber.

[0083] The high-voltage feedthrough 22 is welded through the flange of the measurement main body 10, and is connected with the high-voltage source plug-in through a high-voltage cable outside the vacuum; and is connected with the upper and lower symmetrical plate electrodes 211 and the left and right symmetrical strip electrodes 212 through metal electrode strips inside the vacuum.

[0084] The high-voltage feedthrough 22 needs to have high-voltage transmission capacity of each channel (corresponding to the voltage requirement of different electrodes), and each high-voltage feedthrough 22 can independently adjust the voltage (such as 0 kV to-10 kV) and transmit the voltage to the plate electrodes 211 and the strip electrodes 212, and the specific link is as follows:

[0085] The left and right symmetrical strip electrodes 212 are key regulation nodes, and by adjusting the voltage, the potential difference of the left and right symmetrical strip electrodes 212 can be changed, so as to form a gradient electric field (such as edge field enhancement or uniform electric field) in the region. For example: if the upper and lower symmetrical plate electrodes 211 are connected with-10 kV and 0 V respectively, the two symmetrical strip electrodes 212 are a group, and are short-circuited by metal electrode strips and supplied with the same potential, and from top to bottom, they are-8 kV, -6 kV, -4 kV, -2 kV, etc., and finally a relatively uniform three-dimensional electric field distribution is formed in the chamber.

[0086] Through the symmetrical design of the electrode frame body 21 and the coordinated regulation of the voltage dividing electrodes, combined with the precise power supply of the multi-channel high-voltage source and the design of the permanent magnet blocks outside the upper and lower electrode plates, a stable and controllable electrostatic magnetic field is finally generated in the chamber, which meets the strict requirements of ion beam current measurement (such as three-dimensional profile analysis) on the electric field environment.

[0087] In specific work, the secondary electrons are accelerated to move towards the detection end (below) under the action of the electrostatic magnetic field (10 kV potential difference between the upper and lower plate electrodes 211), forming a directional electron flow, avoiding signal loss caused by thermal diffusion.

[0088] Continuing to refer to Figure 3 In some embodiments of the present application, the radio frequency deflection assembly 30 includes a deflection electrode plate 31, a capacitive coupling feedthrough 33, a tuning electrode plate 34 and a tuning motor 35.

[0089] The deflection electrode plate 31 is composed of two symmetrical metal electrode plates, which are vertically placed (such as X-Y plane) along the electron beam motion direction (set as Z axis), and a transverse force is applied to the electron beam by an electric field to realize deflection or focusing.

[0090] The deflection electrode plate 31 is connected with a high-voltage guide rod 32, and the high-voltage guide rod 32 is connected with an external direct-current high-voltage source to feed static high voltage to the deflection electrode plate 31.

[0091] Wherein, the high-voltage guide rod 32 needs to be fixed to the flange or support structure of the measurement main body 10 to prevent vibration from causing the plate spacing deviation (affecting the uniformity of the electric field); the output voltage of the high-voltage guide rod 32 needs to match the area and spacing of the deflection plate 31 (for example, when the plate spacing is 10 mm, a 10 kV voltage can generate an electric field strength of 1 MV / m).

[0092] If a negative voltage is applied between the two symmetrical metal plates (for example, -10 kV is applied to the left and right plates), an electric field pointing to the center area is formed between the plates. The discrete electrons in the electron beam are deflected to the center under the action of the electric field force, offsetting the beam broadening caused by space charge effects or initial divergence, and achieving beam focusing.

[0093] If a transverse gradient electric field is applied between the plates (for example, only the horizontal plate is applied with voltage), the electron beam will be deflected in the X or Y direction under the action of the transverse Coulomb force (F=qE), changing the beam trajectory and achieving electrostatic field scanning.

[0094] The capacitive coupling feedthrough 33 is inserted into the measurement main body 10 and forms a capacitor between the deflection plates 31. RF power source is fed into the resonant cavity using capacitive coupling. The capacitive coupling feedthrough 33 includes one or more metal probes (or electrodes) inserted into the second chamber 14 through an insulating hole in the vacuum chamber wall. The probe and the deflection plate 31 in the chamber form a capacitor, and the RF power is transmitted through capacitive coupling.

[0095] The tuning plate 34 is telescopic in the 1 / 2 or 1 / 4 wavelength cylindrical resonant cavity, made of oxygen-free copper, and the inner wall is polished. The center axis of the tuning plate 34 is located between the two symmetrical metal plates and forms a capacitor. By inserting and pulling out, the size of the capacitor is changed to adjust the frequency of the resonant cavity.

[0096] The tuning motor 35 is connected to the tuning plate 34 for driving its telescopic motion to change the capacitance and adjust the resonant frequency. The tuning motor 35 can be a servo motor with an absolute position encoder for precise position driving in the sub-millimeter range, realizing small frequency adjustment around the resonant frequency.

[0097] In the electrostatic field scanning mode (two-dimensional section measurement):

[0098] The deflection plate 31 (symmetrical metal plate) of the RF deflection assembly 30 is applied with a DC negative high voltage (for example, -10 kV to the left plate and 0 V to the right plate), forming a uniform electrostatic field. At this time, there is no RF electric field component, only for transverse particle deflection.

[0099] The secondary electrons migrated from the electrostatic magnetic field assembly 20 enter the radio frequency deflection area, and due to the difference in the beam cross section (Y direction) and the position at which the secondary electrons are generated (e.g. close to the upper pole plate or the lower pole plate), the time or speed at which the secondary electrons enter the lower electrostatic field also differs. For example, the secondary electrons generated close to the lower part of the Y direction first pass through the slit into the lower electrostatic field, have a relatively small initial speed, are deflected by the right electric field force, and have a relatively short Y direction travel distance when reaching the right MCP detector; on the contrary, the secondary electrons generated close to the upper part of the Y direction have a relatively high initial speed (have a larger kinetic energy due to the acceleration distance in the upper electric field), are deflected by the same lateral electric field, and have the same time when reaching the right MCP detector, but due to the difference in the initial speed, the Y direction travel distance is larger. Finally, the position at which the secondary electrons bombard the collection area directly reflects the Y direction distribution of the original beam cross section, and the X direction intensity distribution and profile information of the secondary electrons after passing through the horizontal slit are also completely retained, thereby achieving the function of measuring the two-dimensional profile of the beam.

[0100] That is, a uniform electrostatic field is formed by applying a direct current negative high voltage between the deflection pole plates 31. After the secondary electrons enter the second chamber 14, the intensity distribution in the horizontal X direction is retained, and due to the difference in the position at which the secondary electrons are generated in the Y direction of the beam, the time and initial speed at which the secondary electrons enter the lower electrostatic field also differ, the lower electrostatic field can sweep away the distribution in the vertical Y direction, and the function of measuring the two-dimensional profile of the beam is achieved.

[0101] In the radio frequency electric field scanning mode (beam bunch length measurement):

[0102] When the alternating electric field changes with time, the time at which the radio frequency power is fed in is adjusted through the phase shifter, when the electron group representing the beam bunch distribution information reaches, if the sine alternating field is zero potential difference at this time, most of the electrons pass through the deflection pole plate straightly and a larger current signal is obtained, and high-precision phase scanning is continued, the electrons are affected by the deflection field and lost at the second slit, and a gradually weakened current signal is obtained, so that the time distribution of the longitudinal beam bunch is converted into the spatial distribution of the signal electrons through scanning, and the function of measuring the beam bunch length with high resolution is achieved.

[0103] That is, the difference between the two embodiments of the present application lies in the pressurization mode of the lower field frame, and the two embodiments cannot be executed simultaneously. In one of the embodiments of the present application, the deflection electrostatic field provided by the high-voltage guide rod 32 is combined with the integrated micro-channel plate 42 and phosphor screen to convert the signal electrons into a detectable light image, thereby achieving the function of measuring the two-dimensional profile of the beam in the transverse direction.

[0104] In the second embodiment of the present application, the same negative high-voltage focusing field provided by the high-voltage guide rod 32 is combined with the radio frequency deflection field input through the capacitive coupling feedthrough, and the longitudinal time distribution of the signal electrons is converted into the transverse spatial distribution through the second-slit lower punch amplifier and I-V conversion module, thereby achieving the function of measuring the longitudinal beam bunch length.

[0105] Please continue to refer toFigure 3 In some embodiments of the present application, the beam profile measurement component 40 further comprises an optical imaging system in addition to the microchannel plate 42 and the phosphor screen.

[0106] The microchannel plate 42 is arranged on the side wall of the second chamber 14 for avalanche amplification of the secondary electrons. The phosphor screen is arranged behind the output of the microchannel plate 42 for generating fluorescence of a specific wavelength after electron bombardment, realizing an electro-optical conversion process.

[0107] The optical imaging system comprises a lens and a CCD or CMOS camera mounted outside the right flange of the measurement main body 10, collects the fluorescence signal of the phosphor screen, and transmits it to the computer for image processing and data fitting. The fluorescence intensity distribution reflects the lateral density of the signal electrons, and also reflects the two-dimensional profile distribution of the primary beam.

[0108] In specific operation, the secondary electrons, MCP avalanche amplification, phosphor screen fluorescence, image acquisition, software analysis (gray scale distribution → beam two-dimensional profile).

[0109] Further, the beam profile measurement component 40 further comprises a side plate 41 made of metal (such as stainless steel or aluminum alloy) as a mounting base plate of the microchannel plate 42 and the phosphor screen integrated component, which is fixed to the deflection pole plate 31 and maintains the same potential as the deflection pole plate 31. The side plate 41 is provided with a hollow wire mesh, which can be a metal wire mesh or a punched metal plate.

[0110] The hollow wire mesh is fixed behind the side plate 41 by positioning pins or precision clamps, ensuring that its input surface (electron incident surface) is perpendicular to the electron beam axis and located at the position of the hollow wire mesh. The hollow wire mesh provides an unobstructed transmission channel for the electron beam, while compensating for the abnormal electric field distribution in the cutout area and reducing the profile measurement error.

[0111] By arranging the microchannel plate 42 and the phosphor screen integrated component on the side plate 41 with a hollow wire mesh, the incident electron beam is converted into a high-sensitivity, high-spatial-resolution optical signal.

[0112] Continuing to refer to Figure 3 In some embodiments of the present application, the bunch length measurement component 50 comprises a punch-through amplifier 51 and an I-V conversion module. The punch-through amplifier 51 is arranged on the measurement main body 10 and located below the position of the second slit, for amplifying the remaining signal electrons passing through the second slit.

[0113] The I-V conversion module is connected to the output end of the punch-through amplifier 51, for converting the current signal output by the punch-through amplifier into voltage, which is then collected by electronics or observed by an oscilloscope, and combined with the RF sweep phase data fitting to obtain the longitudinal bunch distribution.

[0114] In the embodiment of the present application, the remaining signal electron is twice amplified by the punch-and-hold amplifier 51, and the time precision of the bunch length measurement is realized by combining a high-speed oscilloscope or a digital acquisition card, thereby meeting the dynamic monitoring requirement of a high-power accelerator.

[0115] Figure 5 Figure is a schematic diagram of the design principle of the non-blocking beam three-dimensional profile measurement device provided by the embodiment of the present application. Figure (a) is a principle diagram of the electrostatic field scanning mode (two-dimensional profile measurement). Figure (b) is a principle diagram of the radio frequency electric field scanning mode (bunch length measurement). Figure 6 Figure is an electric field equipotential line distribution diagram under the electrostatic field scanning mode (two-dimensional profile measurement).

[0116] Referring to Figure 5 and Figure 6 The embodiment of the present application further provides a measurement method based on the above-mentioned non-blocking beam three-dimensional profile measurement device, comprising the following steps:

[0117] The corresponding electrostatic high voltage is fed into the electrostatic magnetic field assembly 20, the secondary electrons generated by the ionization of the beam and residual gas move towards the detection end, and enter the radio frequency deflection assembly 30 below through the first slit;

[0118] A direct current negative high voltage and zero potential are respectively applied to the deflection electrode plates 31 of the radio frequency deflection assembly 30, wherein -10kV is applied to the left electrode plate, and 0V is applied to the right electrode plate to form a uniform electrostatic field for lateral particle deflection;

[0119] When the secondary electrons driven from the electrostatic magnetic field assembly 20 enter the radio frequency deflection area, two-dimensional profile measurement can be realized by the electrostatic field scanning below due to the different positions in the beam cross section and the different kinetic energies.

[0120] The embodiment of the present application further provides a measurement method based on the above-mentioned non-blocking beam three-dimensional profile measurement device, comprising the following steps:

[0121] The corresponding electrostatic high voltage is fed into the electrostatic magnetic field assembly 20, the secondary electrons generated by the ionization of the beam and residual gas move towards the detection end, and enter the radio frequency deflection assembly 30 below through the first slit;

[0122] An equal direct current negative high voltage is applied to the deflection electrode plates 31 of the radio frequency deflection assembly 30, wherein -10kV is applied to the left electrode plate, and -10V is applied to the right electrode plate to focus the signal electrons and avoid beam divergence; at the same time, the radio frequency power is input to the deflection electrode plates 31 through the capacitive coupling feedthrough 33, and an alternating electric field is generated between the deflection electrode plates 31;

[0123] The alternating electric field changes with time, and the time of the radio frequency power feed can be adjusted by the phase shifter. When the electron group representing the bunch distribution information arrives, the sine alternating field is just zero potential difference, at this time most of the electrons pass through the deflection plate straightly and get a larger current signal, and the high-precision phase scanning is continued. The electrons will be affected by the deflection field and lost in the second slit, and a gradually weakened current signal is obtained. Therefore, the time distribution of the longitudinal bunch can be converted into the spatial distribution of the signal electrons by scanning, so that the function of high-resolution bunch length measurement is realized.

[0124] By Figure 6 It can be seen that the electric field direction of the upper electromagnetic field frame and the beam passing area is vertically upward, and the product electrons of the ionization of the residual gas move downward. After passing through the upper slit, the electrons enter the lower radio frequency deflector area, at this time the electric field direction is horizontally left, and the low-energy electrons move to the upper part of the MCP on the right, and the higher-energy electrons move to the lower part of the MCP for amplification and collection.

[0125] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A non-blocking beam current three-dimensional profile measurement device, characterized in that, The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device.

2. The non-intercepting beam current three-dimensional profile measurement device of claim 1, wherein, The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device.

3. The non-intercepting beam current three-dimensional profile measuring apparatus according to claim 2, wherein The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device.

4. The non-intercepting beam current three-dimensional profile measurement device of claim 1, wherein, The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device.

5. The non-intercepting beam current three-dimensional profile measuring device according to claim 4, characterized in that The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. The application relates to a beam profile and bunch length measurement device. 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The application relates to a beam profile A micro-channel plate is arranged on the side wall of the second chamber, and the inner surface of the micro-channel aperture of the micro-channel plate is coated with an easy electron emission coating for avalanche amplification of the secondary electrons; A phosphor screen is arranged behind the output of the micro-channel plate for generating fluorescence of a specific wavelength after electron bombardment to realize an electro-optical conversion process; An optical imaging system is arranged on the measurement main body for collecting the fluorescence signal of the phosphor screen and transmitting the signal to a computer for image processing and data fitting.

6. The non-intercepting beam current three-dimensional profile measuring apparatus according to claim 5, wherein The beam current profile measurement component further comprises: A side plate is fixedly arranged on the deflection pole plate and maintains the same potential as the deflection pole plate, and a hollow wire mesh is arranged on the side plate; The micro-channel plate is arranged behind the side plate and at the position of the hollow wire mesh, the hollow wire mesh provides an unobstructed transmission channel for the electron beam and can compensate for the abnormal electric field distribution in the cutout area to reduce the profile measurement error.

7. The non-intercepting beam current three-dimensional profile measuring apparatus according to claim 1, wherein, The bunch length measurement component comprises: A repeller amplifier is arranged on the measurement main body and below the position of the second slit for amplifying the residual signal electrons passing through the second slit; An I-V conversion module is connected to the output end of the repeller amplifier for converting the current signal output by the repeller amplifier into a voltage, which is then collected by electronics or observed by an oscilloscope, and the longitudinal bunch distribution is obtained by combining the radio frequency phase scanning data fitting.

8. The non-blocking beam current three-dimensional profile measuring apparatus according to any one of claims 1 to 7, characterized in that, The measurement main body comprises: A cylindrical main body having flanges at both ends; A shielding member is arranged in the middle region of the cylindrical main body to divide the internal space of the cylindrical main body into the first chamber and the second chamber distributed along the axial direction.

9. A method of measurement based on the non-blocking beam current three-dimensional profile measurement device according to any one of claims 4 to 6, characterized in that, The method comprises the following steps: The corresponding electrostatic high voltage is fed into the electrostatic magnetic field assembly, the secondary electrons generated by the ionization of the beam current and residual gas move towards the detection end and pass through the first slit into the radio frequency deflection assembly below; A direct current negative high voltage and zero potential are respectively applied to the deflection pole plates of the radio frequency deflection assembly, wherein -10kV is applied to the left pole plate and 0V is applied to the right pole plate to form a uniform electrostatic field for lateral particle deflection; When the secondary electrons driven from the electrostatic magnetic field assembly enter the radio frequency deflection region, two-dimensional profile measurement can be realized by electrostatic field scanning due to the difference in position in the beam cross section and the difference in kinetic energy.

10. A method of measurement based on the non-blocking beam current three-dimensional profile measurement device according to any one of claims 4 to 6, characterized in that, The method comprises the following steps: The corresponding electrostatic high voltage is fed into the electrostatic magnetic field assembly, the secondary electrons generated by the ionization of the beam current and residual gas move towards the detection end and pass through the first slit into the radio frequency deflection assembly below; An equal direct current negative high voltage is applied to the deflection pole plates of the radio frequency deflection assembly, wherein -10kV is applied to the left pole plate and -10V is applied to the right pole plate to focus the signal electrons and avoid beam divergence; at the same time, radio frequency power is input to the deflection pole plates through capacitive coupling feedthrough to generate an alternating electric field between the deflection pole plates; The alternating electric field changes with time, and the time of radio frequency power feeding can be adjusted by phase shifter. When the electron group representing the bunch distribution information arrives, the sine alternating field is just zero potential difference, at this time most of the electrons go straight through the deflection plate and get a larger current signal. High precision phase scanning is continued, and the electrons will be affected by the deflection field and lost in the second slit, and a gradually weakened current signal is obtained. Therefore, the time distribution of the longitudinal bunch can be converted into the spatial distribution of the signal electrons by scanning, so as to realize the function of high resolution bunch length measurement.

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