WO2012005629A9 - Procédé et source de génération d'un rayonnement d'arrêt - Google Patents

Procédé et source de génération d'un rayonnement d'arrêt Download PDF

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Publication number
WO2012005629A9
WO2012005629A9 PCT/RU2011/000479 RU2011000479W WO2012005629A9 WO 2012005629 A9 WO2012005629 A9 WO 2012005629A9 RU 2011000479 W RU2011000479 W RU 2011000479W WO 2012005629 A9 WO2012005629 A9 WO 2012005629A9
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Prior art keywords
pulse
pulses
specified
charged particles
level
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PCT/RU2011/000479
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English (en)
Russian (ru)
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WO2012005629A1 (fr
Inventor
Олег Юрьевич МАСЛЕННИКОВ
Василий Иваиович ШВЕДУНОВ
Original Assignee
Maslennikov Oleg Jurievich
Shvedunov Vasily Ivanovich
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Application filed by Maslennikov Oleg Jurievich, Shvedunov Vasily Ivanovich filed Critical Maslennikov Oleg Jurievich
Priority to CN201180038971.XA priority Critical patent/CN103314647B/zh
Publication of WO2012005629A1 publication Critical patent/WO2012005629A1/fr
Publication of WO2012005629A9 publication Critical patent/WO2012005629A9/fr

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H9/00—Linear accelerators
    • H05H9/04—Standing-wave linear accelerators
    • H05H9/048—Lepton LINACS

Definitions

  • the invention relates to accelerator technology for inspection systems using technologies for generating and accelerating charged particles in accelerating structures in a pulsed mode with adjustable beam energy and providing bremsstrahlung with a change in energy level from pulse to pulse between two given values and to the design of linear accelerators for these goals.
  • Pulse linear accelerators of charged particles are widely used in customs inspection complexes to control the contents of heavy containers.
  • a beam of accelerated charged particles is focused on a brake target mounted at the output of the accelerating structure, from the generated bremsstrahlung using a collimator, a sector beam is formed having a small width in the direction of movement of the inspected object, a part of the radiation transmitted through the inspected object is recorded by a line of detectors. Based on the signals of the detectors, the image of the object content is reconstructed.
  • the magnetron operates in a non-optimal mode with a significantly narrowed range of changes in high-frequency power, and, consequently, the energy of the accelerated accelerator beam, which negatively affects sensitivity of the method of detection of substances.
  • the level of the amplified a high-frequency power klystron is achieved by varying from pulse to pulse the amplitude of a low-power high-frequency input signal having a constant frequency with a constant amplitude of a high-voltage pulse supplied to the klystron cathode.
  • this provides a wider range of changes in the energy level, greater stability of the energy of the accelerated beam in a pulse, and the dose rate of bremsstrahlung in a pulse.
  • the single-beam klystrons currently used have large dimensions and mass because of the need to use a solenoid to focus a beam of charged particles in an accelerator, operate at a high voltage requiring oil isolation, which significantly increases the size and cost of electron accelerators created on their basis.
  • a linear electron accelerator is known that can be used in the mode of changing the energy level from pulse to pulse (RU, 2282955, C2), containing an electron source, a microwave generator, power and control devices, an accelerating system, which contains a grouping section with a standing wave and accelerating a traveling wave section, each of which contains connected cells, with tubes on the axis for the drift of the accelerated electron beam and windows on the periphery for electromagnetic coupling, while the accelerator contains a device in the input high-frequency power connected to the first cell along the beam accelerating section bordering the last cell of the grouping section, and microwave power output device, connected to the last cell of the accelerating section.
  • the change in the energy level from pulse to pulse can be carried out by changing the current of accelerated particles, which, presumably, should not affect the amplitude of the accelerating field in the grouping part of the accelerating system and, due to the load by the beam current, reduce the energy gain in the accelerating part.
  • the main disadvantage of the accelerator described above is the relationship between the dose rate and the beam energy, which does not allow independent control of the dose rate for the beam energy level in each pulse separately.
  • a second accelerating section adapted to receive said impulses of charged particles from said first section and to transfer energy to said impulses of charged particles;
  • phase shifter installed between the specified power source and the specified second accelerating section, adapted to alternately change the phase of these electromagnetic waves and for delivering these electromagnetic waves to the specified second accelerating section in the desired phase.
  • a known electron accelerator with a traveling wave (US, 7,130,371, B2) for generating high-energy bremsstrahlung with a change in the level of energy of bremsstrahlung from pulse to pulse between two values and with independent regulation of the dose rate for each energy value, including a source of bremsstrahlung, a high-frequency power system a modulator of the control electrode of the three-electrode electron gun, providing a change in the current level of the beam of the electron gun from pulse to pulse; high-voltage power system, cooling system, accelerator controller, control console and brake target.
  • the bremsstrahlung source comprises an injector adapted to generate an electron beam from a first voltage pulse or second voltage pulse and to transmit it to an accelerating section adapted to generate and accelerate pulses of an electron beam by means of pulses of an electromagnetic signal.
  • the high-frequency power system includes at least two master oscillators adapted to generate pulses of the first electromagnetic signal of the first frequency and pulses of the second electromagnetic signal of the second frequency; a switch adapted for transmitting said pulses of an electromagnetic signal of a first frequency or said pulses second-frequency electromagnetic signal, the pathogen and, as an amplifier, a klystron to amplify the amplitude of the indicated pulses of the electromagnetic signal.
  • the high-voltage power supply system comprises a modulator of said klystron, an injector modulator adapted to generate said first voltage pulse of a first amplitude and said second voltage pulse of a second amplitude, and a synchronization device of said injector modulator and klystron modulator.
  • the radiation spectrum of the known accelerator is suitable for identifying various materials.
  • the indicated device and the method for generating bremsstrahlung implemented with its help allow changing the energy level of the accelerated beam and the current value of the accelerated beam from pulse to pulse.
  • the basis of the change in the beam energy level in the specified device is the dependence of the phase velocity of the electromagnetic wave in the accelerating structure with a traveling wave on the frequency of the electromagnetic signal. With increasing frequency of the electromagnetic signal, the phase velocity of the electromagnetic wave and, consequently, the energy of the accelerated beam, decrease.
  • the change in the current level of the accelerated beam is based on the dependence of the current of the injector — a three-electrode electron gun — on the voltage at the control electrode. As the voltage at the control electrode increases, the beam current of the injected and accelerated beam increases.
  • an accelerating structure on a traveling wave (US, 7,130,371, B2) excludes the possibility of creating a compact accelerator, since it is known that to achieve the same energy of the accelerated beam at the same power of the microwave source (klystron, magnetron), the length of the accelerating structure on the traveling wave should be approximately twice greater than the length of the accelerating structure with a standing wave.
  • an accelerating structure on a traveling wave requires installation on top of its initial part is bulky and high-power solenoid for holding and focusing the beam. Since the field level of the solenoid cannot be switched from pulse to pulse, the described device does not allow obtaining an equally well focused beam at high and low energies.
  • the closest analogue and prototype of the present invention is a method for generating bremsstrahlung with different energy levels (WO 2010/019228; US, 2010/0038563, A1), in which they carry out:
  • the specified method is implemented using a device for generating bremsstrahlung with different energy levels (WO 2010/019228; US, 2010/0038563, A1), containing:
  • a high-frequency power generator for selectively supplying the first and second high-frequency power pulses to the accelerating structure, while the second high-frequency power pulses have a power and frequency different from the first power and the first frequency of the first high-frequency power energy pulses;
  • the first means for matching the first frequency of the power generator with the first resonant frequency of the accelerating structure during the time the first pulses of high-frequency power are fed into it made, for example, in the form of a controller;
  • the collision of which accelerated electrons causes the generation of radiation and the collision of the first accelerated charged particles with the target leads to the generation of radiation having a first energy level, and a collision of the second accelerated charged particles leads to the generation of radiation having a second energy level different from the first level.
  • the device may comprise an electric power source adapted to supply electric power to said power generator, wherein the electric power source may be adapted to selectively supply at least a first or second different voltage to a charged particle source for supplying at least at least the first and second different particle currents into the accelerating structure.
  • the device when a magnetron is used as a high-frequency power generator, the device contains a modulator for selectively controlling the magnetron at the first electric power for generating the first high-frequency power pulses and for controlling the magnetron at the second electric power different from the first electric power to generate second high-frequency power pulses , and the source of electrical power can be separated from the modulator connected to the electron gun, and the module op may be formed solid.
  • the first frequency of the first high-frequency power pulses is matched with the first resonant frequency of the accelerating structure using the first automatic frequency control, and the second frequency of the second high-frequency power pulses is matched using the second automatic frequency control, different from the first adjustment.
  • a magnetron is used, the frequency of the generated oscillations of which can vary from pulse to pulse due to a change in the voltage of the supplying electric power, and to ensure the accuracy of the frequency setting, controlling and correcting devices.
  • This principle of operation of a device with a magnetron is automatically transferred to a version of the device with a klystron as a power source, which makes it inoperative without additional clarifications. The design of the klystron is not described.
  • the aim of the present invention is to simplify the method of generating bremsstrahlung and a device for its implementation for use as inspection systems and providing generation of bremsstrahlung with a change in energy level from pulse to pulse between two preset values, reducing the dimensions of the device and increasing the reliability of its operation.
  • the task was to develop a method for generating bremsstrahlung with the possibility of changing the energy level from pulse to pulse between two preset values, providing dose rate control independently for each given energy level due to the generation of pulsed beams of charged particles having the same energy level and a different current level from one another, acceleration of the first particle beam to the first predetermined energy level and the second particle beam to second of a predetermined energy level by exposure to high-frequency power pulses having different specified high-frequency power levels and the same frequency, with the possibility of changing the power levels of these pulses simultaneously with changing current levels of the first and second beam of charged particles, while ensuring synchronization of the processes of supplying these high-frequency power pulses and processes of supplying current pulses of beams, and the task was to develop a device that ensures the implementation of nd method for generating bremsstrahlung.
  • the problem was solved by creating a method for generating bremsstrahlung, in which they provide a change in the energy level from pulse to pulse between two preset values and the ability to control the dose rate level for each given energy level, while: - generation of bremsstrahlung is carried out by acting on the brake target in a pulsed mode sequentially alternately by the first and second beams of accelerated charged particles, providing the same predetermined dose rate of bremsstrahlung and having a predetermined beam energy level and a predetermined beam current different from one another, wherein :
  • - acceleration of the first and second beams of charged particles to a first predetermined energy level and a second predetermined energy, respectively, is carried out using an accelerating structure with a standing wave by exposing the first and second beams of charged particles in pairs of high frequency power pulses closely spaced in time, having different from other specified levels of high-frequency power and the same frequency, while providing:
  • a predetermined dose rate of bremsstrahlung is provided by adjusting the current magnitude of said first and second beams of charged particles.
  • the accelerating structure of the stream including the first and second beams of charged particles generated by the electron gun, to expose the accelerating field of a low level of tension, leading to modulation of the velocity of the particles, providing a partial grouping of the particles of the stream into bunches, then partially grouped into subject the flow clumps to an accelerating field of a higher level, providing acceleration, additional bunching of particles into particles and focusing of the flow and then expose the flow to an accelerating field with a strength higher than previously used, and to ensure focusing and acceleration of the focused flow to a given speed.
  • the problem was also solved by creating a device for generating bremsstrahlung with a change in the energy level from pulse to pulse between two preset values and the ability to control the dose rate for each of the preset energy levels, containing:
  • bremsstrahlung a source of bremsstrahlung, including:
  • an accelerating structure for accelerating charged particles equipped with resonators and made in the form of an accelerating structure with a standing wave;
  • a source of charged particles adapted to generate and pulse supply of beams of charged particles to the resonators of the accelerating structure, which is used as an electron gun, providing the ability to switch the current value from pulse to pulse between two preset values, while the electron gun is made of a three-electrode and contains a cathode, anode and control electrode;
  • a pulsed multipath amplification klystron adapted for amplification and sequential sequentially supplying to the resonators an accelerating structure of the first and second high-frequency power pulses having predetermined power levels and the same frequency different from each other, and equipped with a focusing system with permanent magnets;
  • the pathogen adapted for sequential pulse supply to the specified klystron of the first high-frequency power and the second high-frequency power of a low level, different levels of high-frequency power, and made with the possibility of changing the level of the first and second high-frequency power supplied to the input of the klystron, between two specified values from pulse to the accelerator pulse of operation, at the same frequency of generated oscillations for both energy values;
  • a source of electrical power made in the form of a modulator, adapted to supply electrical power to the specified klystron and to the cathode of the specified electron gun, and the levels of the indicated electrical power are the same for the first and second energy, and adapted to supply the indicated electrical pulses by pairs of pulses closely spaced time, with the time interval between pulses in a pair, much smaller than the time interval between these pairs of pulses, and providing the ability to control value current of said first and second beams by changing the level of said voltage pulse, and
  • an electric power source for the control electrode of the electron gun adapted for supplying to the control electrode alternately electric pulses of different amplitudes corresponding to the specified energy levels of these particle beams, while being adapted to supply these electric pulses with pairs of pulses closely spaced in time with an interval of time between pulses in a pair, much smaller than the time interval between these pairs of pulses, and providing the possibility of regulation the current value of the specified first and second beams by changing the level of the specified voltage pulse;
  • the device is equipped with a control system that provides a change in the energy level of the beams of accelerated charged particles from pulse to pulse by sending commands to the specified controller, providing a change in the energy levels of these high-frequency power pulses simultaneously with a change in the current levels of the first and second beam.
  • the modulator was configured to power the klystron and the cathode of the electron gun first electrical power, providing a klystron amplification of both of these pulses of high-frequency power and the generation of an electron gun of both beams of charged particles.
  • the modulator was a solid-state modulator.
  • said pathogen contain a synthesizer, a solid-state microwave amplifier and an electronic attenuator with p-i-d diodes.
  • the accelerating structure contains a first cell, which is grouping with a low level of the accelerating field, a second cell, which is accelerating and focusing with a level of the accelerating field higher than in the first cell, the third and subsequent cells, which are accelerating and focusing with the same level of the accelerating field higher than in the second cell, while supplying these clumps from the first cell to the second cell, the distance between the centers of the gaps of the first and second cells is provided ival center position accelerated clot in the region of the maximum of the accelerating field at the second cell field phase shift between cells 180 °.
  • the distance L G between the centers of the gaps of the first and second cells is determined by the ratio
  • I the electromagnetic wavelength of the high-frequency power source in free space
  • c the speed of light
  • n 1, 2, 3 ...
  • the high-frequency voltage U G of the accelerating field at the gap of the first cell is selected from the condition of ensuring the maximum amplitude of the first harmonic of the beam current in the center of the gap of the second cell, provided:
  • a communication loop is installed in the wall of said accelerating structure to provide control the level of the accelerating field and the corresponding energy level of the accelerated beam of charged particles.
  • said accelerating structure and said electron gun are placed inside a screen of soft magnetic material.
  • an ionization chamber is installed on the side of the indicated target, facing the exit of the bremsstrahlung.
  • said electron gun and said accelerating structure located inside said screen be mounted together with said brake target and said ionization chamber inside a local radiation protection, in which a cut would be made to allow formation and removal into the surrounding space beam of bremsstrahlung.
  • the high-frequency power system be equipped with a waveguide that provides the direction of the high-frequency power pulses amplified by the indicated klystron to the specified accelerating structure, and the indicated electron gun, the specified accelerating structure and the specified electronic conductor with the specified brake placed inside the specified radiation protection the target would form a single vacuum volume, isolated from the environment and equipped with a vacuum window placed in the specified waveguide and permeable to these high-frequency pulses.
  • the pumping system was installed on the specified waveguide, including a getter pump that does not require a power source, ensuring a high vacuum level in the specified vacuum volume during the life of the device and communicated with the specified vacuum volume through slots in a narrow the wall of the specified waveguide.
  • an electric discharge pump is installed on said waveguide, the current value of which is determined by the level of vacuum in said vacuum volume, in communication with said vacuum volume through slots in a narrow wall of said waveguide.
  • FIG. 1 is a diagram of a device for generating bremsstrahlung according to the invention, an embodiment
  • FIG. 2 is a mode diagram of a device for generating bremsstrahlung shown in FIG. 1;
  • FIG. 3 energy spectrum of an accelerated beam of charged particles in the mode of changing the energy level from pulse to pulse between two preset values, shown in the coordinates of the dependence of the average current I av of the beam on the energy level E of the beam;
  • FIG. 4 - images of one and the other beam with different energy levels in a pair of pulses sequentially arriving at the brake target: Figa, and 2 - for a beam with a low energy level; 4b, b 15 b 2 - for a beam with a high level of energy, for comparison - the image of the scale grid with a step of 1 mm.
  • FIG. 5 is a perspective view of an apparatus for generating bremsstrahlung according to the invention in the embodiment shown in FIG.
  • a method for generating bremsstrahlung with a change in the energy level from pulse to pulse between two predetermined values according to the invention can be implemented using a device for generating bremsstrahlung in the embodiment shown in FIG. 1.
  • the device ( Figure 1) contains a source of bremsstrahlung 1, a high-frequency power system 2, a high-voltage power system 3, a cooling system 4, a controller 5, and a control system 6.
  • the source 1 of bremsstrahlung includes: - an accelerating structure for accelerating a beam of charged particles, equipped with resonators and made in the form of an accelerating structure 7 with a standing wave;
  • a source of charged particles adapted for generating and pulsed supply of beams of charged particles into the resonators of the accelerating structure 7, which is used as a three-electrode electron gun 8 connected through a ceramic insulator with an accelerating structure 7 and having a cathode 9, a control electrode 10 and an anode (in the drawing not shown), providing the ability to switch the magnitude of the current from pulse to pulse between two preset values;
  • a brake target 12 located at the output of the electron wire 1 1 and providing the generation of bremsstrahlung 13 in a collision with the brake target 12 of an accelerated beam of charged particles coming from the accelerating structure 7 through the electron wire 1 1.
  • the accelerating structure 7 and the electron gun 8 are placed inside the screen 14 of magnetically soft material.
  • an ionization chamber 15 is installed.
  • the electron gun 8 and the accelerating structure 6 located inside the said screen 14 together with the electron wire 1 1, the brake target 12, and the ionization chamber 15 are installed in the internal cavity of the local radiation protection 16, in which a slot 17 is made, which ensures the formation and removal into the surrounding space beam of bremsstrahlung 13.
  • a coupling loop 18 is installed in the wall of the accelerating structure 7, providing control of the level of the accelerating field of the accelerating structure 7 and the corresponding energy level of the accelerated charged particle beam 19.
  • the accelerating structure 7 on a standing wave contains a first cell, which is grouping with a low level of the accelerating field, a second cell, which is accelerating and focusing with a level of the accelerating field higher than in the first cell, the third and subsequent cells, which are accelerating and focusing with the same level of the accelerating field higher than in the second cell.
  • the choice of the distance between the centers of the gaps of the first and second cells ensures the position of the center of the accelerated bunch in the region of the maximum of the accelerating field of the second cell when the field phase between the cells is shifted by 180 °.
  • the distance L g between the centers of the gaps of the first and second cells is determined by the ratio:
  • n 1, 2 , 3 ....
  • the high-frequency voltage U g of the accelerating field at the gap of the first cell is selected from the condition of ensuring the maximum amplitude of the first harmonic of the beam current in the center of the gap of the second cell, provided:
  • correction coils 21 can be placed on the outer surface of the accelerating structure 7.
  • a change in the final energy of the beam is achieved by changing the level of high-frequency power entering the accelerating structure 7, while ensuring the ratio of the maximum possible and minimum possible values of the energy of the accelerated beam of at least 2.0, with the beam diameter on the brake target 12 throughout energy variation range not more than 2.0 mm.
  • the high-frequency power supply system 2 includes a pulse amplifying klystron 22 and a pathogen 23. Moreover, the klystron 22 through the waveguide 24, the ferrite decoupling device 25 and the vacuum window 20 provides the direction of high-frequency power pulses amplified a klystron 22, to the accelerating structure 7. Moreover, the waveguide 24 is equipped with an insulating gas supply system 26 and a discharge sensor 27. To prevent high-frequency breakdowns, the waveguide 24 and the ferrite decoupling device 25 are filled with insulating gas. In the event of a discharge on the vacuum window 20, in the waveguide 24 or a ferrite decoupling device 25, the discharge sensor 27 generates a blocking signal that disables the generation of a high-frequency signal by the pathogen 23.
  • the pulse amplification klystron 22 is adapted to amplify and sequentially sequentially feed into the resonators of the accelerating structure 7 first and second high-frequency power pulses having different set power levels and the same frequency, and is equipped with a permanent magnet focusing system (not shown in the drawing);
  • a small-sized multipath klystron similar, for example, to the KIU-147 A klystron (Multy-beam klystrons with reverse permanent magnet focusing system as the universal rf power sources for the compact electron accelerators, LA. Frejdovich, PV, can be used) Nevsky, VP Sakharov et al, in Proceedings of RuPAC 2006, Novosibirsk, Russia, p. 100), which operates at low voltage, which allows the use of a small-sized modulator, while electron beams are created using a multipath electron gun and pass them through klystron resonators and drift tubes in a magnetic field, creating permanent magnets.
  • This design of the klystron allows, together with devices for controlling the frequency of the pathogen, to provide a sharp reduction in the mass and dimensions of the device for generating bremsstrahlung.
  • the pulse amplifier klystron 22 operating at a low voltage due to the use of a multi-beam design, is compact due to the use of a focusing system with permanent magnets and provides excitation of the microwave field of the accelerating structure 7.
  • the possibility of using a low-voltage, therefore, small-sized solid-state modulator for klystron 22 can significantly reduce dimensions of the structure even when creating a magnetic field by a solenoid.
  • the pulsed multipath amplification klystron 22 has a large gain, which allows the use of a pathogen 23 with a low output power, providing the ability to maintain high frequency stability; the value of its output power may vary from pulse to pulse with the desired repetition rate.
  • the causative agent 23 is electrically connected to the klystron 22 and is adapted for sequential pulse supply to the klystron 22 of the first high-frequency power and the second high-frequency low-power power, differing in high-frequency power levels, and is configured to change the level of the first and second high-frequency power supplied to the input of the klystron 22, between two set values from pulse to pulse of the source 1 of bremsstrahlung 13, at the same frequency of generated oscillations for both energy values .
  • the pathogen 23 contains a synthesizer, a solid-state microwave amplifier and an electronic attenuator on p-i-n diodes (not shown in the drawing).
  • a pumping system 28 is placed on the waveguide 24, including a getter pump (not shown separately in the drawing), which does not require a power source, which maintains a high level of vacuum in the above-mentioned vacuum volume during the life of the device and communicates with the vacuum volume through the slots in the narrow wall of the specified waveguide 24.
  • the pumping system 28 contains mounted on the waveguide 24 is an electric discharge pump (not shown separately in the drawing), the current value of which is determined by the vacuum level in the indicated vacuum volume, and communicated with the vacuum volume through the slots in the narrow wall of the waveguide 24.
  • the indicated vacuum volume is pumped out mainly by a getter pump, and the electric discharge pump used to control the level of vacuum. This allows you to quickly enter the source into operating mode after prolonged storage, guarantees stability of parameters and reliability of the system.
  • System 3 high voltage power supply contains:
  • an electric power source made in the form of a modulator 29, adapted to supply electric power to the klystron 22 and to the cathode 9 of the electron gun 8, and the levels of the indicated electric power are the same for the first and second energy and - source 30 of electrical power for the control electrode 10 of the electron gun 8.
  • the modulator 29 is electrically connected to the klystron 22 and is adapted to supply electric pulses to the klystron 22 with pairs of pulses closely spaced in time, with a time interval between pulses in a pair much smaller than the time interval between these pulse pairs, and makes it possible to control the magnitude the current of the first and second beams by changing the level of the voltage pulse at the cathode 9 of the electron gun 8.
  • the modulator 29 is made solid-state with the possibility of supplying the klystron 22 and the cathode 9 of the electron gun 8 with the first electric power, which provides the klystron 22 to amplify both of these high-frequency power pulses and generate by the electron gun 8 both charged particle beams.
  • the electric power source 30 of the control electrode 10 of the electron gun 8 is adapted for supplying to the control electrode 10 alternately electric pulses of different amplitudes corresponding to predetermined energy levels of particle beams.
  • the electric power source 30 is adapted to supply the indicated electrical pulses with pairs of pulses closely spaced in time, with the time interval between pulses in pairs being much smaller than the time interval between these pairs of pulses, and makes it possible to control the current magnitude of the first and second beams by changing level of the specified voltage pulse.
  • the cooling system 4 includes a liquid cooling device 31, a system 32 of sensors for measuring temperature and liquid flow, and provides cooling of the accelerating structure 7, klystron 22, modulator 29, and brake target 12.
  • the controller 5 is electrically connected to a source of bremsstrahlung 13, a high-frequency power supply system 2, a high-voltage power supply system 3, a cooling system 4, and is adapted to synchronize the time that the klystron 22 supplies the first high-frequency power pulse to the accelerating structure 7 with the current pulse of the first electron beam charged gun 8; synchronization of the time of supply of the second pulse of high-frequency power to the accelerating structure 7 with the time of supply of the current pulse of the second beam electron gun 8; synchronizing the repetition rate of pairs of current pulses of the first and second beams of charged particles generated by the electron gun 8 with the repetition rate of pairs of high-frequency power pulses generated by the pathogen 23 and the repetition rate of pairs of high-frequency power pulses to be amplified by klystron 22.
  • the operation of the controller 5 can be illustrated as shown in FIG. 2 by a diagram of the operating modes of the device for generating bremsstrahlung with synchronization of the specified parameters of the time of supply of the indicated energy, power and current pulses, where ⁇ is the pulse duration, T1 is the distance between pulses in a pair of pulses, Tg is the distance between pairs of pulses.
  • ⁇ is the pulse duration
  • T1 is the distance between pulses in a pair of pulses
  • Tg is the distance between pairs of pulses.
  • a change in the magnitude of the beam current is provided by a change in the magnitude of the voltage across the control electrode 10 of the electron gun 8.
  • the device according to the invention is equipped with a control system 6, providing a change in the energy level of the beams of accelerated charged particles from pulse to pulse by giving the controller 5 commands, providing a change in the energy levels of high-frequency power pulses simultaneously with a change in the current levels of the first and second beam.
  • a method for generating bremsstrahlung in which a change in the energy level from pulse to pulse between two predetermined values and the ability to control the dose rate level for each predetermined energy level is provided, is carried out in the above-described device for generating bremsstrahlung as follows.
  • commands are generated for the controller 5 to supply an energy signal to the high-frequency power supply system 2 and the high-voltage power supply system 3.
  • the energy signal of the controller 5 determines the power of the high-frequency pulse generated by the pathogen 23, and, thus, determines the amplitude of the accelerating field in the accelerating structure 7, the energy of the accelerated beam and the upper limit of the spectrum of bremsstrahlung 13.
  • the energy signal of the controller 5 determines the voltage on the control electrode 10 of the electron gun 8 and, thus, the magnitude of the current of the electron gun 8, the magnitude of the accelerated beam current and the dose rate of the bremsstrahlung 13.
  • the cathode 9 of the electron gun 8 By supplying to the cathode 9 of the electron gun 8 the voltage pulses generated by the modulator 29, which are the same for the given energy levels, and by simultaneously supplying to the control electrode 10, the electric pulses of different amplitudes different for the given energy levels generated by the electric energy source 30, provide generation of the electron gun 8 alternating first and second beams of charged particles having the same energy level and a different current level from one another, while supplying said and pulses are carried out by pairs of pulses closely spaced in time, with a time interval between pulses in a pair much less than the time interval between these pairs of pulses.
  • the electric power supplied to the klystron 22 remains unchanged.
  • the electron gun 8 provides the injection of the first and second particle beams into the resonators of the accelerating structure 7 with a standing wave.
  • the first and second high-frequency power pulses amplified by the klystron 22 are sequentially fed to the resonators of the accelerating structure 7, exciting an accelerating field in it.
  • the stream containing the first and second beams of charged particles generated by the electron gun 8 is subjected to an accelerating field, which modulates the velocity of the particles, providing a partial grouping of the particles of the stream into bunches, then the partially bunched stream is subjected to an accelerating field of a higher level, providing acceleration , an additional grouping of particles in clumps and focusing of the flow, and then the flow is subjected to an accelerating field with a level higher than previously used, and echivayut focusing and acceleration of the focused stream to a predetermined speed.
  • the first and second beams of charged particles are accelerated to a first predetermined energy level and to a second predetermined energy level, respectively.
  • acceleration is carried out by exposing the first and second beams of charged particles to high-frequency power pulses generated by the pathogen 23 and amplified by the klystron 22 and having different set high-frequency power levels that are different from each other.
  • Filing specified pulses to the resonators of the accelerating structure 7 are carried out by pairs of pulses closely spaced in time, as shown in FIG. 2, with a time interval / between pulses in a pair much smaller than the time interval T 2 between these pulse pairs, which can be, for example, 500 ⁇ s.
  • the timing of the supply of the first first high-frequency power pulse from the klystron 22 to the accelerating structure 7 is synchronized with the timing of the current supply of the first beam of charged particles by the electron gun 8
  • the timing of the second high-frequency power pulse from the klystron 22 is synchronized into the accelerating structure 7 with the time when the electron gun feeds 8 current pulses of the second beam of charged particles, synchronizing the repetition rate of the pairs of current pulses of charged particles, forming emitted by the electron gun 8, with a repetition rate of pairs of the indicated high-frequency power pulses generated by the klystron 22.
  • the electric power supplied to it does not change.
  • the change in the energy of the beams of charged particles from pulse to pulse is carried out by changing the level of the accelerating field of the accelerating structure 7 by changing the level of the output power of the pathogen 23 simultaneously with changing the levels of the first and second currents of the beam of the electron gun 8.
  • FIG. Figure 3 shows the results of measuring the energy spectrum of an accelerated beam of charged particles in the mode of changing the energy level from pulse to pulse between two setpoints performed using a magnetic spectrometer in the coordinates of the dependence of the average current I av of the beam on the energy level E of the beam.
  • the accelerating structure 7 operates at the same frequency, the first high-frequency power pulse of the pulsed multipath klystron 22 is time-synchronized with the first beam current pulse, and the second power pulse is synchronized with the second current pulse.
  • the control of the level of the accelerating field is carried out using a communication loop 18 installed in one of the accelerating cells of the accelerating structure 7.
  • bremsstrahlung 13 is carried out by acting on the braking target 12 in a pulsed mode sequentially alternately first and the second beams of accelerated charged particles, providing the same specified dose rate of bremsstrahlung 13 and having a different beam energy level and a predetermined beam current different from one another.
  • the bremsstrahlung 13 is received at the braking target 12 located at the output of the small diameter electric circuit 1 1 installed at the output of said accelerating structure 7.
  • a predetermined dose rate of bremsstrahlung 13 is provided by adjusting the current magnitude of the first and second beams of charged particles of the electron gun 8.
  • the control of the dose rate of bremsstrahlung 13 is carried out using an ionization chamber 15 installed after the braking target 12.
  • the parasitic magnetic fields in the electron gun 8 and accelerating structure 7 are reduced to a level not exceeding the level of the Earth’s magnetic field using a magnetic shield 14.
  • the adjustment of the position of the beam 19 on the brake target 12 can be implemented using corrective coils 21.
  • FIG. 4 shows mappings of pulses of the first and second beams with different energy levels in a pair of pulses before they collide with the brake target 12: Fig. 4a, ax, a2 — for a beam with a low energy level; 4b, bb 2 - for a beam with a high level of energy, for comparison - the image of the scale grid with a step of 1 mm.
  • Figure 5 shows a General view of a device for generating bremsstrahlung according to the invention in the above embodiment, shown in Figure 1.
  • the method for generating bremsstrahlung according to the invention with the aid of a bremsstrahlung generator according to the invention makes it possible to generate bremsstrahlung from a pulse to a pulse of an energy level between two predetermined values and to enable the dose rate to be adjusted independently for each given energy level.
  • the dimensions of the device are significantly reduced, which is important when using the devices as inspection systems, and the reliability of the device is increased. It will be understood by those skilled in the art of charged particle beam physics that improvements and modifications may be made to the method for generating bremsstrahlung according to the invention and to the device for generating bremsstrahlung without departing from the scope of the claims.
  • a device for generating bremsstrahlung using the method of generating bremsstrahlung according to the invention can be used in inspection complexes, and can be manufactured using known technologies using known materials and equipment.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Particle Accelerators (AREA)
  • Radiation-Therapy Devices (AREA)
  • Apparatus For Disinfection Or Sterilisation (AREA)

Abstract

L'invention concerne un dispositif et un procédé de génération d'un rayonnement d'arrêt avec changement du niveau d'énergie d'impulsion à impulsion entre deux valeurs prédéterminées, utilisé dans des ensemble d'appareils d'inspection, à régulation indépendante de puissance de la dose de rayonnement pour chaque niveau d'énergie. Le dispositif est muni d'une protection locale contre le rayonnement (16), assure un faible diamètre de faisceaux sur la cible d'arrêt (12), et une efficacité élevée d'accélération des particules. Le dispositif comprend une structure d'accélération (7) avec une onde fixe alimentée par un klystron compact à rayons multiples (22) possédant une faible tension du rayon et permettant une focalisation au moyen d'aimants permanents. Le changement de niveau du faisceau de particules chargé (19) s'effectue sur une même fréquence grâce à la variation des niveaux de puissance de sortie du klystron (22) d'impulsion à impulsion et de l'amplitude du champ dans une structure d'accélération (7). La mise en pratique d'un puissance requise de la dose est assurée par le changement d'impulsion à impulsion de la tension de l'électrode de commande (10) du canon électronique (8) et de l'intensité de courant du faisceau injecté dans la structure d'accélération (7).
PCT/RU2011/000479 2010-07-05 2011-07-04 Procédé et source de génération d'un rayonnement d'arrêt WO2012005629A1 (fr)

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RU2566468C1 (ru) * 2014-07-10 2015-10-27 Общество с ограниченной ответственностью "Лаборатория Скантроник" Система интроскопического сканирования инспекционно-досмотрового комплекса и способ, осуществляемый в такой системе
RU2610712C9 (ru) * 2015-09-30 2017-04-27 Общество с ограниченной ответственностью "Лаборатория электронных ускорителей МГУ" Способ генерации тормозного излучения с поимпульсным переключением энергии и источник излучения для его осуществления
US10143076B2 (en) * 2016-04-12 2018-11-27 Varian Medical Systems, Inc. Shielding structures for linear accelerators
CN106540505A (zh) * 2017-02-03 2017-03-29 盐城工学院 电子照射管以及voc废气处理装置
CN107979911A (zh) 2017-12-26 2018-05-01 同方威视技术股份有限公司 用于加速器的抽拉式承载装置和加速器舱体结构
CN107884425A (zh) * 2017-12-26 2018-04-06 同方威视技术股份有限公司 用于矿产成分分析的系统及方法
CN110113859A (zh) * 2019-06-12 2019-08-09 中广核中科海维科技发展有限公司 一种低能辐照直线加速器

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US20080211431A1 (en) * 2000-02-10 2008-09-04 American Science And Engineering, Inc. Pulse-to-Pulse-Switchable Multiple-Energy Linear Accelerators Based on Fast RF Power Switching
WO2004030424A2 (fr) * 2002-09-27 2004-04-08 Scantech Holdings, Llc Accelerateur de particules a grande plage de commande d'energie
WO2004030162A2 (fr) * 2002-09-27 2004-04-08 Scantech Holdings, Llc Systeme pour emettre alternativement des impulsions d'energie d'electrons acceleres bombardant une cible de conversion
RU2246719C1 (ru) * 2003-07-04 2005-02-20 Общество с ограниченной ответственностью "Интроскан" Способ облучения конверсионной мишени импульсами тока ускоренных электронов и устройство для его реализации
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WO2008121820A2 (fr) * 2007-03-29 2008-10-09 American Science And Engineering, Inc. Accélérateurs linéaires à énergies multiples commutables à impulsions successives basés sur une commutation de puissance rf rapide
US8183801B2 (en) * 2008-08-12 2012-05-22 Varian Medical Systems, Inc. Interlaced multi-energy radiation sources

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RU2452143C2 (ru) 2012-05-27
CN103314647A (zh) 2013-09-18
CN103314647B (zh) 2015-11-25
RU2010127452A (ru) 2012-01-10

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