A BNCT target disk temperature detection system and method

Abstract

The application discloses a BNCT target disc temperature detection system and method, which comprises the following steps: growing a magneto-optical film with a thickness of 20+ / -1 nm on the back surface of a rotating lithium target by magnetron sputtering; introducing a double-wavelength laser interference light source into a vacuum target chamber through a coaxial optical fiber probe to form a double-cavity interference link; using centrifugal force generated when the rotating lithium target rotates to make the magneto-optical film produce nanoscale displacement, so that the instantaneous temperature rise of the rotating lithium target is amplified into a phase polarization composite signal which can be optically detected; integrating a miniature slip ring coupling light path to couple the phase polarization composite signal to a stationary end photoelectric detector; inputting the phase polarization composite signal output by the photoelectric detector into a field programmable gate array to solve the transient micro area temperature field of the rotating lithium target in real time; and using the generated transient micro area temperature field as a boundary condition to drive the closed-loop verification and temperature control protection of the rotating lithium target. The application can realize millisecond-level temperature control protection of an ultrathin rotating lithium target.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of boron neutron capture therapy (BNCT), and particularly relates to a BNCT target disc temperature detection system and method. BACKGROUND

[0002] Boron neutron capture therapy (BNCT) is rapidly evolving towards compact accelerators, the core of which is to convert an ultra-thin rotating lithium target into a low-energy neutron source through a 7Li(p,n)7Be reaction under the condition of a 2.5MeV, ≤50kW proton beam. The clinical dosimetry requires a beam spot ≤3mm to match the tumor microzone, while the ultra-thin rotating lithium target has a thickness of only 100-200µm and a very small mass heat capacity; when a 30-50kW microbeam spot is bombarded for a millisecond-level dwell time, the local power density breaks through 2.5kWcm -2 , causing the local temperature rise of the ultra-thin rotating lithium target to exceed the melting point of 180.5°C in <1ms, resulting in melting, bubbling and even peeling. The traditional thermocouple cannot distinguish <100µm scale transient hot spots due to thermal inertia, and the infrared temperature measurement is also difficult to give <100µm spatial resolution and <20µs time resolution data under 6000rpm rotation due to the influence of lithium surface oxidation and emissivity drift. Therefore, there is an urgent need for a new method that can accurately capture the transient temperature field of the ultra-thin rotating lithium target. SUMMARY

[0003] In order to solve the problem that the existing model shows hysteresis and non-adaptability when processing postoperative new data, and is difficult to update the prediction result in real time, the present application provides a BNCT target disc temperature detection system and method.

[0004] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0005] On the one hand, the present application discloses a BNCT target disc temperature detection method, comprising the following steps:

[0006] Step 1: growing a thickness of 20±1nm Co / Pt magneto-optic film on the back surface of the rotating lithium target by magnetron sputtering, the Co / Pt magneto-optic film serving as a temperature-sensitive laser interference coupling layer for converting the instantaneous temperature rise of the rotating lithium target into a polar Kerr angle change;

[0007] Step 2: introducing a dual-wavelength laser interference light source into the vacuum target chamber through a coaxial optical fiber probe, the light beam vertically penetrating the rotating lithium target and the Co / Pt magneto-optic film to form a dual-cavity interference link; the dual-cavity interference link is used for encoding the polar Kerr angle change into an interference phase difference;

[0008] Step 3: The Co / Pt magneto-optical film is caused to produce nanoscale displacement by centrifugal force generated when the lithium target rotates, and the nanoscale displacement and the polar Kerr angle change jointly constitute magneto-optical-interference synergistic amplification, so as to amplify the instantaneous temperature rise of the rotating lithium target into a phase-polarization composite signal that can be optically detected;

[0009] Step 4: A miniature slip ring coupling light path is integrated at the outlet end of the coaxial optical fiber probe, and a polarization beam splitting crystal is embedded in the miniature slip ring coupling light path, so as to couple the phase-polarization composite signal to a stationary end photoelectric detector;

[0010] Step 5: The phase-polarization composite signal output by the photoelectric detector is input into a field programmable gate array, and the transient micro-region temperature field of the rotating lithium target is solved in real time;

[0011] Step 6: The generated transient micro-region temperature field is used as a boundary condition to drive an ANSYS-Adaptive Mesh transient thermal model, and the ANSYS-Adaptive Mesh transient thermal model returns the prediction error to the field programmable gate array, so as to realize closed-loop verification and temperature control protection of the rotating lithium target.

[0012] Further, step 1 comprises: sending the ultra-thin rotating lithium target into a radio frequency-direct current composite magnetron sputtering cavity with a background vacuum of ≤5×10 -5 Pa, first performing argon ion cleaning on the back surface of the ultra-thin rotating lithium target for 120s by using 200W radio frequency plasma, and then depositing a Co / Pt magneto-optical film with a thickness of 20±1nm on the back surface of the ultra-thin rotating lithium target by using a Co-Pt alloy target at a constant rate of 0.11nm·s -1 -1 under the conditions of maintaining the temperature of the ultra-thin rotating lithium target at 80°C, the argon gas pressure at 0.5Pa, and the sputtering power at 300W, so as to convert the instantaneous temperature rise of the ultra-thin rotating lithium target into a polar Kerr angle change, and immediately cooling down to room temperature at a slow cooling rate of 15°C·min -1 -1 after the deposition is completed, so as to ensure that the stress of the Co / Pt magneto-optical film is synchronized with the ultra-thin rotating lithium target.

[0013] Further, step 2 includes: feeding the dual-wavelength laser interference light source (λ = 532 nm and λ = 632 nm) that has passed the power lock control into the vacuum target chamber through a single-mode polarization maintaining optical fiber with an outer diameter of 2.2 mm and a numerical aperture of 0.12, the exit end of the polarization maintaining optical fiber is fused into a coaxial optical fiber probe, the end face of the coaxial optical fiber probe is perpendicular to the irradiation surface of the ultra-thin rotating lithium target with a distance of 0.8 mm, so that the coaxial light beam of the dual-wavelength laser interference light source first passes through the front and back surfaces of the ultra-thin rotating lithium target to form a first interference cavity, and then continues to pass through the front and back surfaces of the Co / Pt magneto-optical film to form a second interference cavity, thereby forming a front and back series double-cavity interference link in the same optical path; the double-cavity interference link converts the polar Kerr angle change of the Co / Pt magneto-optical film caused by temperature change into the interference phase difference of the two light beams of 532 nm and 632 nm respectively in real time, and then provides a demodulable temperature encoding signal for the subsequent photoelectric detector.

[0014] Further, step 3 includes: when the ultra-thin rotating lithium target rotates at 6000 rpm, the centrifugal force generated by the mass of the ultra-thin rotating lithium target is transmitted to the Co / Pt magneto-optical film through the elastic deformation of the ultra-thin rotating lithium target, causing the Co / Pt magneto-optical film to have a nanoscale displacement of 5-20 nm in the in-plane direction; the nanoscale displacement and the polar Kerr angle change caused by the instantaneous temperature rise of the Co / Pt magneto-optical film are superimposed in the form of product to form magneto-optical-interference synergistic amplification, wherein the polar Kerr angle change modulates the polarization component of the dual-wavelength laser interference light source, and the nanoscale displacement modulates the phase component of the dual-wavelength laser interference light source, both of which are superimposed in real time in the same optical path, thereby directly generating a phase-polarization composite signal at the output end of the double-cavity interference link, the phase-polarization composite signal carries an instantaneous temperature rise amplification factor of the ultra-thin rotating lithium target ≥20 times, which can be directly read by the subsequent photoelectric detector.

[0015] Further, step 4 includes: at the exit end of the coaxial optical fiber probe, a rotating end single-mode optical fiber with an outer diameter of 1.8 mm and an embedded polarization maintaining fiber core is first coaxially fused with the rotor end face of a micro slip ring coupling light path with an outer diameter of 6.0 mm, a through-hole type, and an insertion loss <1 dB by ultraviolet glue, and then a polarization beam splitting crystal coated with a high-transmission antireflection film is fixed on the stator end face of the micro slip ring coupling light path by ultraviolet glue, so that the phase-polarization composite signal returned after passing through the ultra-thin rotating lithium target and the Co / Pt magneto-optical film is separated into two orthogonal polarization components by the polarization beam splitting crystal in real time inside the micro slip ring coupling light path, and then the two components are simultaneously sent into a stationary end photoelectric detector through the stator end single-mode optical fiber, and are synchronously recorded by the stationary end photoelectric detector at a sampling rate of 50 kHz, so that the 6000 rpm rotation of the ultra-thin rotating lithium target is not interrupted during the entire sampling process.

[0016] Further, step 5 includes: the phase polarization composite signal output by the stationary end photodetector in a differential manner is directly connected to the PL end of a Zynq Ultra Scale+ field programmable gate array through an LVDS high-speed interface. Inside the field programmable gate array, the 532 nm and 632 nm two-way interference phase difference is extracted in real time by using a 128-tap CORDIC hard core. The real-time solution of the transient micro-area temperature field of the ultra-thin rotating lithium target is completed in the ARM hard core of the field programmable gate array with a delay of <50 µs, and the result is written back to the DDR4 shared memory through the AXI-Stream bus for subsequent closed-loop calling.

[0017] Further: in order to let the field programmable gate array generated transient micro-area temperature field truly drive the ANSYS-Adaptive Mesh transient thermal model, and return the prediction error to the field programmable gate array, a real-time middleware based on PetaLinux is run on the PS end of the Zynq Ultra Scale+ field programmable gate array: the middleware captures the transient micro-area temperature field from the PL end in the form of AXI-Stream DMA, and then encapsulates it into a <128 µs period data packet through a 10 GbE UDP / IP protocol stack, and sends it to the ANSYS-Adaptive Mesh transient thermal model host in the same chassis through the RJ-45 interface; at the same time, the ANSYS Mechanical APDL script pre-deployed on the ANSYS-Adaptive Mesh transient thermal model host reads these UDP data packets through the PyAnsys interface, writes the transient micro-area temperature field as a dynamic boundary condition into the model, and completes the thermal-structure coupling calculation with a step size of 0.5 ms. After the calculation is completed, PyAnsys packs the difference between the local hot spot temperature and the transient micro-area temperature field into the same UDP frame, and sends it back to the field programmable gate array through a second 10 GbE link. After receiving the difference packet, the field programmable gate array completes the PID gain update in <20 µs by the PL end hard logic, and drives the micro-piston array located in the coaxial optical fiber probe through the AXI-Lite bus, to achieve millisecond-level temperature control protection for the ultra-thin rotating lithium target.

[0018] On the other hand, the application also discloses a BNCT target disc temperature detection system, comprising:

[0019] Co / Pt magneto-optical film deposition module: a Co / Pt magneto-optical film with a thickness of 20±1 nm is magnetron sputtered and grown on the back surface of the rotating lithium target, which serves as a temperature-sensitive laser interference coupling layer for converting the transient temperature rise of the rotating lithium target into a polar Kerr angle change;

[0020] Dual-wavelength laser interference light source and coaxial optical fiber probe module: a dual-wavelength laser interference light source is introduced into a vacuum target chamber through a coaxial optical fiber probe, a light beam vertically penetrates a rotating lithium target and a Co / Pt magneto-optical film to form a dual-cavity interference link; the dual-cavity interference link is used for encoding a polar Kerr angle change into an interference phase difference;

[0021] Synergistic amplification module: a centrifugal force generated when the rotating lithium target rotates is used to make the Co / Pt magneto-optical film generate a nanoscale displacement, and the nanoscale displacement and the polar Kerr angle change jointly constitute magneto-optical-interference synergistic amplification, so as to amplify the instantaneous temperature rise of the rotating lithium target into a phase polarization composite signal that can be optically detected;

[0022] Miniature slip ring coupling light path and stationary end photoelectric detector module: a miniature slip ring coupling light path is integrated at an outlet end of the coaxial optical fiber probe, a polarization beam splitting crystal is embedded in the miniature slip ring coupling light path, and the phase polarization composite signal is coupled to the stationary end photoelectric detector;

[0023] Coupling inversion module: the phase polarization composite signal output by the photoelectric detector is input into a field programmable gate array, and a transient micro-region temperature field of the rotating lithium target is solved in real time;

[0024] Closed-loop temperature control protection module: the generated transient micro-region temperature field is used as a boundary condition to drive an ANSYS-Adaptive Mesh transient thermal model, and the ANSYS-Adaptive Mesh transient thermal model returns a prediction error to the field programmable gate array, so as to realize closed-loop verification and temperature control protection of the rotating lithium target.

[0025] Compared with the prior art, the technical progress achieved by the application is that:

[0026] Through magneto-optical-interference synergistic amplification of a 50 kHz sampled dual-wavelength laser interference light source and a Co / Pt magneto-optical film, the system breaks through the limit of 50 µm in space and 20 µs in time, and for the first time realizes point-by-point and frame-by-frame imaging of a transient micro-region temperature field of a 100–200 µm thick ultra-thin rotating lithium target under <3 mm proton beam spot bombardment. The entire temperature measurement link only relies on light and magnetic rotation effects, and the surface of the ultra-thin rotating lithium target does not need to be pasted with a thermocouple or coated with a black body layer, nor does it need to be arranged with any micro sensor inside the ultra-thin rotating lithium target, so that no new heat source or heat capacity is introduced, and the authenticity of the lithium layer temperature rise data is ensured. The miniature slip ring coupling light path transmits the phase polarization composite signal from the 6000 rpm ultra-thin rotating lithium target side to the stationary end photoelectric detector in a <1 dB loss and zero brush contact manner, completely eliminating the wear and signal distortion of the traditional slip ring in the vacuum high radiation environment. The field programmable gate array can complete a thermal inversion in <50 µs, and the result is injected into the ANSYS-Adaptive Mesh transient thermal model in real time, so as to realize millisecond-level temperature control protection and avoid lithium layer melting. Attached Figure Description

[0027] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0028] In the attached diagram:

[0029] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0030] The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of the present invention will now be described with reference to the accompanying drawings.

[0031] Example 1

[0032] like Figure 1 As shown, this invention discloses a BNCT target disk temperature detection method, comprising:

[0033] Step 1: A Co / Pt magneto-optical thin film with a thickness of 20±1nm is grown by magnetron sputtering on the back surface of a rotating lithium target. The Co / Pt magneto-optical thin film serves as a temperature-sensitive laser interference coupling layer to convert the instantaneous temperature rise of the rotating lithium target into a change in the poloidal Kerr angle.

[0034] Step 2: A dual-wavelength laser interference source is introduced into the vacuum target chamber through a coaxial fiber optic probe. The beam penetrates perpendicularly through the rotating lithium target and the Co / Pt magneto-optical thin film, forming a dual-cavity interference link. The dual-cavity interference link is used to encode the poloidal Kerr angle variation as an interference phase difference.

[0035] Step 3: Utilize the centrifugal force generated when the rotating lithium target rotates to induce nanoscale displacement in the Co / Pt magneto-optical thin film. The nanoscale displacement and the change in the poloidal Kerr angle together constitute magneto-optical interference synergistic amplification, thereby amplifying the instantaneous temperature rise of the rotating lithium target into a phase-polarized composite signal that can be optically detected.

[0036] Step 4: Integrate a miniature slip ring coupling optical path at the exit end of the coaxial fiber probe. The miniature slip ring coupling optical path is embedded with a polarization beam splitter crystal to couple the phase polarization composite signal to the stationary end photodetector.

[0037] Step 5: Input the phase-polarization composite signal output by the photodetector into the field-programmable gate array to calculate the transient micro-region temperature field of the rotating lithium target in real time;

[0038] Step 6: The generated transient micro-zone temperature field is used as a boundary condition to drive the ANSYS-Adaptive Mesh transient thermal model, which in turn feeds the prediction error back to the field programmable gate array to achieve closed-loop verification and temperature control protection for the rotating lithium target.

[0039] Specifically, step 1 includes:

[0040] In a radio frequency-direct current composite magnetron sputtering cavity with a total volume of 0.15 m³ and a background vacuum that can be maintained at ≤5×10 -5 Pa for a long time, a 100 mm diameter and 100-200 µm thick ultra-thin rotating lithium target is fixed concentrically on a rotating heating table that can be closed-loop temperature controlled in the range of 0-300 °C by a Ta clamp, with the back surface of the ultra-thin rotating lithium target facing upwards and parallel to the sputtering target plane, and the distance is set to 60 mm. Then, 20 sccm of 99.999% pure argon is introduced, and a 200 W, 13.56 MHz radio frequency plasma is ignited at an initial pressure of 1 Pa. The back surface of the ultra-thin rotating lithium target is cleaned in situ by 120 s of argon ion bombardment to remove the 1.5-2 nm natural oxide layer and adsorbed hydrocarbons. After cleaning, the temperature of the ultra-thin rotating lithium target is maintained at 80 °C, the argon pressure is reduced to 0.5 Pa, and the Co-Pt alloy target is switched on. A 300 W direct current power is used to continuously sputter for 180 s at a constant deposition rate of 0.11 nm·s -1 The ultra-thin rotating lithium target is rotated at a constant speed of 5 rpm to ensure thickness uniformity. Finally, a 20±1 nm thick Co / Pt magneto-optical film is deposited on the back surface of the ultra-thin rotating lithium target. After deposition, the ultra-thin rotating lithium target is cooled to room temperature at a rate of 15 °C·min -1 -1 using a PID temperature control curve, and is placed in a 0.1 MPa high-purity nitrogen atmosphere for 300 s to eliminate residual tensile stress, so that the stress field of the Co / Pt magneto-optical film and the ultra-thin rotating lithium target is fully matched, providing a high repeatability reference for subsequent polar Kerr angle changes.

[0041] Specifically, step 2 includes:

[0042] First, on the vibration isolation optical platform, a dual-wavelength laser interference light source with a center wavelength locking accuracy better than ±0.3 pm and a power stability of <0.1% is preheated and power-locked: two independent temperature-controlled Nd:YVO4 solid-state lasers output 532 nm and 632 nm single longitudinal mode beams, which are collinearly combined and then pass through a PZT-driven acousto-optic modulator to achieve a small frequency shift of ±20 kHz for subsequent phase-locked demodulation.

[0043] Then, the combined coaxial light beam is coupled into a single-mode polarization maintaining fiber with an outer diameter of 2.2 mm, a numerical aperture of 0.12, and a cutoff wavelength of 500 nm. The single-mode polarization maintaining fiber is sealed by a CF35 flange at the transition section of the outer wall of the vacuum target chamber and penetrates into the interior of the target chamber through a stainless steel protective sleeve with a wall thickness of 1 mm. The inside of the sleeve is filled with low outgassing epoxy resin to prevent micro-vibration. The exit end of the single-mode polarization maintaining fiber is precisely ground to an 8° bevel, and then fused with a quartz collar with the same bevel to form a coaxial fiber probe. An adjustable GRIN lens is installed at the front end of the coaxial fiber probe to keep the collimated light beam diameter at 1.0 mm and the divergence angle <0.5 mrad. The end face of the coaxial fiber probe is kept perpendicular to the irradiation surface of the ultra-thin rotating lithium target with a distance of 0.8 mm by means of a three-axis piezoelectric nanometer positioning table.

[0044] The coaxial light beam of the dual-wavelength laser interference light source passes through the front and back surfaces of the ultra-thin rotating lithium target in turn to form a first interference cavity (cavity length = instantaneous thickness of the ultra-thin rotating lithium target), and then continues to penetrate the front and back surfaces of the Co / Pt magneto-optical film to form a second interference cavity (cavity length = thickness of the Co / Pt magneto-optical film 20 nm). The two cavities are connected in series on the same optical axis, forming a front-back series dual-cavity interference link. The dual-cavity interference link converts the polar Kerr angle change of the Co / Pt magneto-optical film caused by temperature change into the interference phase difference of the two light beams of 532 nm and 632 nm in real time, and encodes the phase difference in the polarization state and phase of the coaxial light beam, thereby providing a temperature encoding signal that can be directly demodulated for the subsequent stationary photodetector.

[0045] Specifically, step 3 includes:

[0046] When the ultra-thin rotating lithium target is rotating at 6000 rpm, the instantaneous angular velocity ω is sent in real time to the field programmable gate array (FPGA) installed on the central axis of the ultra-thin rotating lithium target, and the FPGA immediately calls the centrifugal force analytical formula ρ·h·r·ω² to calculate the in-plane stress field σ(r) of the ultra-thin rotating lithium target point by point in the range of r∈[0mm, 50mm] with a step of 0.5mm; the stress field is converted into the in-plane strain ε(r) through the Young's modulus E=4.9GPa and the Poisson's ratio v=0.36 of the ultra-thin rotating lithium target, and the ε(r) is transmitted to the Co / Pt magneto-optical film through the 1.5µm thick adhesive layer of the ultra-thin rotating lithium target, so that the Co / Pt magneto-optical film generates a nanoscale displacement of 5-20nm in the in-plane direction; the nanoscale displacement and the polar Kerr angle change caused by the instantaneous temperature rise of the Co / Pt magneto-optical film are superimposed in the form of product to form a magneto-optical-interference synergistic amplification, wherein the polar Kerr angle change directly modulates the polarization component of the dual-wavelength laser interference light source, and the nanoscale displacement modulates the phase component of the dual-wavelength laser interference light source by changing the optical path difference between the first interference cavity and the second interference cavity of the dual-cavity interference link, and the two are superimposed in real time in the same optical path to directly generate a phase-polarization composite signal at the output end of the dual-cavity interference link; the ultra-thin rotating lithium target instantaneous temperature rise amplification coefficient carried by the phase-polarization composite signal is ≥20 times, which can be directly read by the subsequent stationary end photoelectric detector, and provides high signal-to-noise ratio temperature coding required for millisecond-level closed-loop control of the FPGA.

[0047] Specifically, step 4 comprises:

[0048] In order to transfer the phase-polarization composite signal output by the dual-cavity interference link from the 6000 rpm ultra-thin rotating lithium target side to the stationary end photoelectric detector completely and without distortion, first, a 6mm diameter through hole is drilled in the vacuum target chamber side wall, and a micro slip ring coupling light path with an outer diameter of 6.0mm and a length of 25mm is installed in a CF16 flange vacuum seal, and the rotor end face is coaxial with the rotation center of the ultra-thin rotating lithium target; then, the rotating end single-mode optical fiber with an outer diameter of 1.8mm and an embedded polarization maintaining fiber core is coaxially fused with the rotor end face of the micro slip ring coupling light path by using ultraviolet glue with a refractive index of 1.56, the glue layer thickness is controlled within 5µm, and the fusion point is cured under a 365nm UV lamp for 60s to ensure that the radial runout is <1µm at 6000rpm.

[0049] On the stator end face of the micro slip ring coupling light path, a 3mmx3mmx1mm polarization beam splitting crystal with 532nm / 632nm high transmittance and antireflection film on both sides is fixed by the same ultraviolet glue. The fast axis of the polarization beam splitting crystal is aligned with the polarization maintaining axis of the rotating end single mode fiber with an accuracy of <0.2°, so that the returned phase polarization composite signal is separated into s-polarization and p-polarization orthogonal components in real time inside the micro slip ring coupling light path; the two components are coupled out through the stator end single mode fiber with a 2.5mm diameter ceramic plug, and are connected to the two independent channels of the stationary end photodetector through FC / APC joints. The field programmable gate array provides a 50kHz external sampling clock for the stationary end photodetector through SMA coaxial line, thereby ensuring that the 6000rpm rotation of the ultra-thin rotating lithium target is not interrupted by any mechanical means during the entire sampling process.

[0050] Specifically, step 5 includes:

[0051] In order to let the phase polarization composite signal output by the stationary end photodetector in a differential manner complete the real-time calculation of the ultra-thin rotating lithium target transient micro-area temperature field inside the Zynq UltraScale+ field programmable gate array, this step is developed on both the hardware and algorithm fronts, and the specific technical means are as follows:

[0052] The dual-channel output of the stationary end photodetector first enters two 14-bit, 125MSPS ADCs (ADS4222). The two ADCs are directly connected to the PL end BANK 64 / 65 of the Zynq UltraScale+ field programmable gate array through FMC-HPC connector in the form of LVDS differential pair. The sampling clock is generated by the MMCM of the field programmable gate array to generate a 50kHz external sampling clock, which is returned to the ADC as SYSREF, ensuring that the system jitter is <100fs.

[0053] On the PL end, the 128-tap parallel CORDIC hard core performs real-time arctangent operation on the 532nm and 632nm two-way interference phase, outputting a 14-bit phase word; at the same time, a 14-bit parallel multiplier array synchronously demodulates the polar Kerr angle change of the Co / Pt magneto-optical film, obtaining the polarization component directly corresponding to the temperature-thickness coupled inversion algorithm. The two data streams are merged into a 32-bit phase polarization composite signal in the AXI-Stream FIFO and sent to the DDR4 shared memory in zero-copy mode.

[0054] The temperature-thickness coupled inversion algorithm is completely resident in the on-chip BRAM of the Zynq UltraScale+ field programmable gate array, and is composed of the following four sub-modules:

[0055] a) Refractive index temperature variation model: where , .

[0056] b) Thermal expansion thickness model: , .

[0057] c) Kerr angle temperature coefficient of Co / Pt magneto-optic film: , obtained by experimental calibration.

[0058] d) Nonlinear least squares solver: Levenberg-Marquardt algorithm is adopted, and it can converge in 4 iterations of floating-point operations in ARM hard core, and each iteration takes <12 µs; the solver outputs and ( ), and then the instantaneous temperature rise of the ultra-thin rotating lithium target is calculated.

[0059] where represents the instantaneous refractive index of the ultra-thin rotating lithium target at temperature and wavelength .

[0060] represents the reference refractive index of the ultra-thin rotating lithium target at the reference temperature (typically 20°C), and the experimental calibration value.

[0061] represents the refractive index temperature coefficient of the ultra-thin rotating lithium target, with the unit of ; subscript represents the corresponding wavelength.

[0062] represents the temperature increment of the ultra-thin rotating lithium target relative to the reference temperature , with the unit of , which is the core unknown quantity of the inversion solver.

[0063] represents the instantaneous thickness of the ultra-thin rotating lithium target at temperature , with the unit of m.

[0064] represents the reference thickness of the ultra-thin rotating lithium target at the reference temperature , with the unit of m.

[0065] represents the linear thermal expansion coefficient of the ultra-thin rotating lithium target, with the unit of .

[0066] represents the thickness increment of the ultra-thin rotating lithium target due to the temperature rise , By Linear derivation, unit m.

[0067] Indicates the temperature coefficient of the polar Kerr angle of the Co / Pt magneto-optical film, unit , indicates the sensitivity of the polar Kerr angle of the Co / Pt magneto-optical film with temperature.

[0068] The whole pipeline is driven by AXI-DMA, the phase polarization demodulation and data packaging are completed at the PL end, the ARM hard core completes the inversion operation, the AXI-Stream bus writes the results back to the DDR4 shared memory and immediately returns to the host computer through the 1 GbE UDP, and the measured delay is <45 µs, which meets the millisecond-level closed-loop temperature control protection requirements of the field programmable gate array for the ultra-thin rotating lithium target.

[0069] Specifically, step 6 includes:

[0070] In order to let the transient micro-zone temperature field generated by the field programmable gate array really drive the ANSYS-Adaptive Mesh transient thermal model, and return the prediction error to the field programmable gate array, the embodiment runs a real-time middleware based on PetaLinux at the PS end of the Zynq UltraScale+ field programmable gate array: the middleware captures the transient micro-zone temperature field from the PL end in the AXI-Stream DMA mode, then encapsulates it into a <128μs period data packet through the 10 GbE UDP / IP protocol stack, and sends it to the ANSYS-Adaptive Mesh transient thermal model host in the same chassis through the RJ-45 interface; at the same time, the ANSYS Mechanical APDL script pre-deployed on the ANSYS-Adaptive Mesh transient thermal model host reads these UDP data packets through the PyAnsys interface, writes the transient micro-zone temperature field as a dynamic boundary condition into the model, and completes the thermal-structure coupling calculation with a step size of 0.5ms, after the calculation is completed, PyAnsys packs the difference between the local hot spot temperature and the transient micro-zone temperature field into the same UDP frame, and sends it back to the field programmable gate array through the second 10 GbE link; after receiving the difference packet, the field programmable gate array completes the PID gain update in <20μs by the PL end hard logic, and drives the micro-piston array in the coaxial optical fiber probe through the AXI-Lite bus, to realize the millisecond-level temperature control protection of the ultra-thin rotating lithium target.

[0071] Example 2

[0072] A BNCT target disc temperature detection system, characterized by comprising:

[0073] Co / Pt magneto-optical film deposition module: a Co / Pt magneto-optical film with a thickness of 20±1 nm is grown on the back surface of the rotating lithium target by magnetron sputtering, and the Co / Pt magneto-optical film is used as a temperature-sensitive laser interference coupling layer to convert the transient temperature rise of the rotating lithium target into a polar Kerr angle change;

[0074] Dual-wavelength laser interference light source and coaxial optical fiber probe module: a dual-wavelength laser interference light source is introduced into a vacuum target chamber through a coaxial optical fiber probe, and a beam is vertically penetrated through a rotating lithium target and a Co / Pt magneto-optical film to form a dual-cavity interference link; the dual-cavity interference link is used to encode the polar Kerr angle change into an interference phase difference;

[0075] Synergistic amplification module: a centrifugal force generated when the rotating lithium target rotates is used to make the Co / Pt magneto-optical film produce a nanoscale displacement, and the nanoscale displacement and the polar Kerr angle change jointly constitute magneto-optical-interference synergistic amplification, so as to amplify the transient temperature rise of the rotating lithium target into a phase polarization composite signal that can be optically detected;

[0076] Miniature slip ring coupling light path and stationary end photoelectric detector module: a miniature slip ring coupling light path is integrated at an outlet end of the coaxial optical fiber probe, and a polarization beam splitting crystal is embedded in the miniature slip ring coupling light path to couple the phase polarization composite signal to a stationary end photoelectric detector;

[0077] Coupling inversion module: a phase polarization composite signal output by the photoelectric detector is input to a field programmable gate array to solve a transient micro-area temperature field of the rotating lithium target in real time;

[0078] Closed-loop temperature control protection module: the generated transient micro-area temperature field is used as a boundary condition to drive an ANSYS-AdaptiveMesh transient thermal model, and the ANSYS-AdaptiveMesh transient thermal model returns a prediction error to the field programmable gate array to realize closed-loop verification and temperature control protection of the rotating lithium target.

[0079] The modules in the embodiment 2 are used to realize the functions in the embodiment 1. The embodiment can be implemented by a system including a processor and a memory, wherein the memory stores computer program instructions, and when the computer program instructions are executed by the processor, the computer program instructions realize the BNCT target plate temperature detection method according to the embodiment 1 of the present application. The system further includes a communication bus, a communication interface and other components familiar to those skilled in the art, and the settings and functions of the components are known in the art, and thus will not be described here.

[0080] In this application, the aforementioned memory can be any tangible medium that contains or stores a program that can be used by or in connection with an instruction execution system, system, or device. For example, the computer-readable storage medium can be any suitable magnetic storage medium or magneto-optical storage medium, such as resistive random access memory (RRAM), dynamic random access memory (DRAM), static random access memory (SRAM), enhanced dynamic random access memory (EDRAM), high-bandwidth memory (HBM), hybrid memory cube (HMC), and the like, or any other medium that can be used to store the desired information and that can be accessed by an application, module, or both. Any such computer storage media can be part of the device or accessible or connectable thereto. Any application or module described herein can be implemented using computer-readable / executable instructions that can be stored or otherwise held by such computer-readable media.

[0081] Finally, it should be noted that the above-mentioned only for the preferred embodiments of the present application, and not for the purpose of limiting the present application, although the present application is described in detail with reference to the foregoing embodiments, for those skilled in the art, it still can be modified to the technical solution recorded in the foregoing embodiments, or part of the technical features of the equivalent replacement. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the scope of protection of the claims of the present application.

Claims

1. A method for detecting the temperature of a BNCT target disk, characterized in that, include: Step 1: A Co / Pt magneto-optical thin film with a thickness of 20±1nm is grown by magnetron sputtering on the back surface of a rotating lithium target. The Co / Pt magneto-optical thin film serves as a temperature-sensitive laser interference coupling layer to convert the instantaneous temperature rise of the rotating lithium target into a change in the poloidal Kerr angle. Step 2: A dual-wavelength laser interference source is introduced into the vacuum target chamber through a coaxial fiber optic probe. The beam penetrates perpendicularly through the rotating lithium target and the Co / Pt magneto-optical thin film, forming a dual-cavity interference link. The dual-cavity interference link is used to encode the poloidal Kerr angle variation as an interference phase difference. Step 3: Utilize the centrifugal force generated when the rotating lithium target rotates to induce nanoscale displacement in the Co / Pt magneto-optical thin film. The nanoscale displacement and the change in the poloidal Kerr angle together constitute magneto-optical interference synergistic amplification, thereby amplifying the instantaneous temperature rise of the rotating lithium target into a phase-polarized composite signal that can be optically detected. Step 4: Integrate a miniature slip ring coupling optical path at the exit end of the coaxial fiber probe. The miniature slip ring coupling optical path is embedded with a polarization beam splitter crystal to couple the phase polarization composite signal to the stationary end photodetector. Step 5: Input the phase-polarization composite signal output by the photodetector into the field-programmable gate array to calculate the transient micro-region temperature field of the rotating lithium target in real time; Step 6: The generated transient micro-region temperature field is used as the boundary condition to drive the ANSYS-Adaptive Mesh transient thermal model. The ANSYS-Adaptive Mesh transient thermal model then feeds back the prediction error to the field programmable gate array to realize closed-loop verification and temperature control protection of the rotating lithium target.

2. The BNCT target disk temperature detection method according to claim 1, characterized in that, Step 1 includes: The rotating lithium target is introduced into a background vacuum ≤5×10 -5 The RF-DC hybrid magnetron sputtering cavity was first cleaned with 200W RF plasma for 120s on the back surface of a rotating lithium target. Then, while maintaining the rotating lithium target temperature at 80°C, argon pressure at 0.5Pa, and sputtering power at 300W, a Co-Pt alloy target was used for sputtering at 0.11nm·s⁻¹. -1 A constant sputtering rate was maintained for 180 s to uniformly deposit a Co / Pt magneto-optical thin film with a thickness of 20 ± 1 nm on the back surface of a rotating lithium target. This Co / Pt magneto-optical thin film serves as a temperature-sensitive laser interference coupling layer, converting the instantaneous temperature rise of the rotating lithium target into a poloidal Kerr angle change. Immediately after deposition, the film was sputtered at a constant rate of 15°C·min. -1 The temperature is gradually reduced to room temperature at a slow cooling rate to ensure that the stress of the Co / Pt magneto-optical film is synchronized with the rotating lithium target.

3. The BNCT target disk temperature detection method according to claim 2, characterized in that, Step 2 includes: The dual-wavelength laser interference source has wavelengths of 532nm and 632nm. It is fed into the vacuum target chamber through a single-mode polarization-maintaining fiber with an outer diameter of 2.2mm and a numerical aperture of 0.

12. The output end of the polarization-maintaining fiber is fused into a coaxial fiber probe. The end face of the coaxial fiber probe is perpendicular to the irradiation surface of the rotating lithium target and is 0.8mm away. This allows the coaxial beam of the dual-wavelength laser interference source to first pass through the front and rear surfaces of the rotating lithium target to form a first interference cavity, and then continue to pass through the front and rear surfaces of the Co / Pt magneto-optical thin film to form a second interference cavity. Thus, a dual-cavity interference link is formed in series in the same optical path. The dual-cavity interference link converts the poloidal Kerr angle change of the Co / Pt magneto-optical thin film caused by temperature change into the interference phase difference of the two beams of 532nm and 632nm in real time, thereby providing a demodulated temperature-coded signal for the subsequent photodetector.

4. The BNCT target disk temperature detection method according to claim 3, characterized in that, Step 3 includes: When the rotating lithium target rotates at 6000 rpm, the centrifugal force generated by the mass of the rotating lithium target itself is transmitted to the Co / Pt magneto-optical film through the elastic deformation of the rotating lithium target, causing the Co / Pt magneto-optical film to undergo a nanoscale displacement of 5–20 nm in the in-plane direction. The nanoscale displacement and the change in the poloidal Kerr angle of the Co / Pt magneto-optical film caused by the instantaneous temperature rise are superimposed in a product form to form a magneto-optical-interference synergistic amplification. The change in the poloidal Kerr angle modulates the polarization component of the dual-wavelength laser interference source, while the nanoscale displacement modulates the phase component of the dual-wavelength laser interference source. The two are superimposed in real time in the same optical path, thereby directly generating a phase-polarized composite signal at the output end of the dual-cavity interference link. The phase-polarized composite signal carries an instantaneous temperature rise amplification factor of ≥20 times for the rotating lithium target.

5. The BNCT target disk temperature detection method according to claim 4, characterized in that, Step 4 includes: At the exit end of the coaxial fiber optic probe, a rotating single-mode fiber with an outer diameter of 1.8 mm and an embedded polarization-maintaining fiber core is first coaxially fused to the rotor end face of a miniature slip ring coupling optical path with an outer diameter of 6.0 mm, a through-hole design, and an insertion loss of <1 dB, using UV adhesive. Then, a polarization beam splitter crystal coated with a high-transmittance antireflection film is fixed to the stator end face of the miniature slip ring coupling optical path using UV adhesive. This allows the phase polarization composite signal returning after passing through the rotating lithium target and the Co / Pt magneto-optical film to be separated into two orthogonal polarization components in real time inside the miniature slip ring coupling optical path by the polarization beam splitter crystal. Subsequently, these two components are simultaneously sent to the stationary end photodetector through the stator end single-mode fiber, and the stationary end photodetector records them synchronously at a sampling rate of 50 kHz, thus maintaining the 6000 rpm rotation of the rotating lithium target without interruption throughout the sampling process.

6. The BNCT target disk temperature detection method according to claim 5, characterized in that, Step 5 includes: The phase-polarization composite signal output differentially from the stationary photodetector is directly connected to the PL terminal of a Zynq Ultra Scale+ field-programmable gate array (FPGA) via an LVDS high-speed interface. Inside the FPGA, the phase difference between the two interference paths at 532nm and 632nm is extracted in real time using a 128-tap CORDIC hard core. The transient micro-area temperature field of the rotating lithium target is calculated in real time with a delay of <50µs in the ARM hard core of the FPGA, and the result is written back to the DDR4 shared memory via the AXI-Stream bus.

7. The BNCT target disk temperature detection method according to claim 6, characterized in that, Step 6 includes: To ensure that the transient micro-area temperature field generated by the field-programmable gate array (FPGA) truly drives the ANSYS-Adaptive Mesh transient thermal model and feeds back the prediction error to the FPGA, a real-time middleware based on PetaLinux runs on the PS (Power Supply) end of the Zynq Ultra Scale+ FPGA. This middleware captures the transient micro-area temperature field from the PL (Power Supply) end using AXI-Stream DMA, then encapsulates it into data packets with a period of <128μs via a 10 GbE UDP / IP protocol stack, and sends them to the ANSYS-Adaptive Mesh transient thermal model host in the same chassis via an RJ-45 interface. Simultaneously, ANSYS Mechanical, pre-deployed on the ANSYS-Adaptive Mesh transient thermal model host... The APDL script reads UDP packets through the PyAnsys interface, writes the transient micro-region temperature field as a dynamic boundary condition into the model, and completes the thermal-structural coupling calculation in 0.5ms steps. After the calculation, PyAnsys packages the difference between the local hot spot temperature and the transient micro-region temperature field into the same UDP frame and sends it back to the field-programmable gate array (FPGA) via a second 10GbE link. After receiving the difference packet, the FPGA updates the PID gain within <20μs using the PL-side hard logic and drives the micro-piston array located in the coaxial fiber probe via the AXI-Lite bus to achieve closed-loop verification and temperature control protection of the rotating lithium target.

8. A BNCT target plate temperature detection system, characterized in that, include: Co / Pt magneto-optical thin film deposition module: A Co / Pt magneto-optical thin film with a thickness of 20±1nm is grown by magnetron sputtering on the back surface of a rotating lithium target. The Co / Pt magneto-optical thin film serves as a temperature-sensitive laser interference coupling layer to convert the instantaneous temperature rise of the rotating lithium target into a change in the poloidal Kerr angle. Dual-wavelength laser interference source and coaxial fiber optic probe module: The dual-wavelength laser interference source is introduced into the vacuum target chamber through a coaxial fiber optic probe. The beam penetrates perpendicularly through the rotating lithium target and the Co / Pt magneto-optical thin film, forming a dual-cavity interference link; the dual-cavity interference link is used to encode the poloidal Kerr angle change as an interference phase difference. Synergistic amplification module: Utilizing the centrifugal force generated when the rotating lithium target rotates, the Co / Pt magneto-optical thin film is displaced at the nanoscale. The nanoscale displacement and the change in the poloidal Kerr angle together constitute magneto-optical interference synergistic amplification, thereby amplifying the instantaneous temperature rise of the rotating lithium target into a phase-polarized composite signal that can be optically detected. Miniature slip ring coupled optical path and stationary end photodetector module: A miniature slip ring coupled optical path is integrated at the exit end of the coaxial fiber probe. The miniature slip ring coupled optical path is embedded with a polarization beam splitter crystal to couple the phase polarization composite signal to the stationary end photodetector. Coupled Inversion Module: Inputs the phase-polarization composite signal output from the photodetector into the field-programmable gate array to calculate the transient micro-region temperature field of the rotating lithium target in real time; Closed-loop temperature control protection module: The generated transient micro-area temperature field is used as the boundary condition to drive the ANSYS-AdaptiveMesh transient thermal model. The ANSYS-AdaptiveMesh transient thermal model then feeds back the prediction error to the field programmable gate array to realize closed-loop verification and temperature control protection of the rotating lithium target.

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