Bremsstrahlung diode is an important device for obtaining large area uniform bremsstrahlung field in laboratory. In this paper, based on Monte Carlo method, a model of single and double ring parallel electron beam bombarding tantalum target is established to simulate the process of bremsstrahlung field generated by ring diode. The electron beam energy is 1.5 MeV, the tantalum target thickness is 200 μm, and the dose of bremsstrahlung field generated by a single ring electron beam 10 cm behind the target is simulated by detector counting method. For single-ring diode structure, the inner diameter of the ring is the main factor affecting the bremsstrahlung field uniformity behind the target, and the larger the inner diameter, the worse the central dose uniformity. Compared with the inner diameter of the ring, the ring width mainly affects the dose of the radiation field, but has little influence on the uniformity. When the inner diameter of a single ring is 19 cm and the outer diameter is 20 cm, a uniform radiation field with a maximum area of 2290.221 cm2 can be obtained. When the inner diameter of a single ring is 19 cm and the outer diameter is 20 cm, a uniform radiation field with a maximum area of 2290.221 cm2 can be obtained. The double-loop diode structure can obtain a larger area of uniform radiation field than the single-loop structure. However, the variation of the outer ring diameter leads to multi-level peaks in the dose distribution of the radiation field, which also affects the homogeneity of each region of the radiation field. The simulation results show that by adding a concentric outer ring with an inner diameter of 43.5 cm and an outer diameter of 44.167 cm to the outside of the single ring structure, the radiation field area meeting the uniformity requirement can be increased to 7238.229 cm2.

FLASH radiotherapy delivers the entire dose to the target area within milliseconds using ultra-high dose rates, rendering existing online dosimeters essentially ineffective. Currently, radiation-sensitive films are commonly employed for dose measurement. Utilizing an electron accelerator developed by the Institute of Applied Electronics of CAEP, an electron FLASH radiotherapy platform was established to investigate the dose rate range and dose distribution using the EBT3 film’s rapid readout method. Experimental results indicate that the rapid readout method of EBT3 films is applicable for dose measurement in electron FLASH radiotherapy, with dose rates ranging from 240 Gy/s to 290 Gy/s at a source-to-skin distance of 100 cm and a depth of 1 cm. Fluctuations in the average energy of the electron beam reaching the surface of the phantom result in dose fluctuations of approximately ±5% in the target area. The surface dose distribution meets the requirements of flatness within ±5% and symmetry within ±3%.

The investigation of hydrodynamic instability growth in convergent geometry is crucial for optimizing the design of inertial confinement fusion capsules, which aims to mitigate the growth of hydrodynamic instability and mixing. Experiments about the hydrodynamic instability of the decelerated inner interface in radiation-driven cylindrical implosions were conducted at 100 kJ laser facility. Mode coupling of perturbations and the Bell-Plesset (BP) effect unique to convergent geometry were observed. The theoretical predictions of the growth induced by the BP effect are consistent with the experimental results. Additionally, these experiments identified a second-order mode introduced by an M2 drive asymmetry. The drive asymmetry is about 11%. To mitigate the drive asymmetry, a method of extending the length of the hohlraum was proposed. Researches of the hydrodynamic instability in cylindrical geometry contribute to a better understanding of how convergent geometry affects hydrodynamic instability growth at high energy density, thereby aiding in optimizing the design of inertial confinement fusion capsules.

There are several issues with traditional microchannel plate (MCP) gated framing cameras used for inertial confinement fusion diagnostic, such as large volume, incapable single line-of-sight (SLOS), and so on. The MCP can be instead by a CMOS chips with time resolution of picosecond-scale to achieve the image with SLOS. This paper presents a SLOS four-frame picosecond CMOS circuit consisting of 8×8×4 pixel arrays, and its performance is simulated. The CMOS circuit includes the design of unit pixel which contains four-frame, delay and control circuitry, binary clock tree, circuitry of row and column selector by using 0.18 μm CMOS process and 5T (5 transistors) unit pixel. The signals in the pixel array of the CMOS circuit are analyzed, ans the simulation results show that the CMOS circuit has the capability to obtain four images with a single exposure. The temporal resolution is 100 ps, the interval between two adjacent images is 300 ps, and the uniformity of intra-pixel signals is better than 90%.

To obtain the equation of state (EOS) of tantalum-niobium alloy (Ta-Nb) materials under high pressure, a type of Al/Ta-Nb impedance matching target for laser EOS experiments was fabricated. The processes of precision rolling and femtosecond laser cutting of Ta-Nb alloy foil were studied. A step sample of Ta-Nb alloy with a thickness of 13 μm and a width of 400 μm was obtained. Ta-Nb alloy step was assembled with Al standard material using polyvinyl alcohol (PVA) hydrosol. The surface morphology, step thickness and sample density of the target were measured by white light interferometer and electronic densitometer. The results show that the Al/Ta-Nb alloy impedance matching target fabricated can meet the requirements of laser EOS experiments.

High-resolution flow field data has important applications in meteorology, aerospace engineering, high-energy physics and other fields. Experiments and numerical simulations are two main ways to obtain high-resolution flow field data, while the high experiment cost and computing resources for simulation hinder the specific analysis of flow field evolution. With the development of deep learning technology, convolutional neural networks are used to achieve high-resolution reconstruction of the flow field. In this paper, an ordinary convolutional neural network and a multi-time-path convolutional neural network are established for the ablative Rayleigh-Taylor instability. These two methods can reconstruct the high-resolution flow field in just a few seconds, and further greatly enrich the application of high-resolution reconstruction technology in fluid instability. Compared with the ordinary convolutional neural network, the multi-time-path convolutional neural network model has smaller error and can restore more details of the flow field. The influence of low-resolution flow field data obtained by the two pooling methods on the convolutional neural networks model is also discussed.

In synchrotrons, the high-frequency ripple error of magnet excitation current causes magnetic field ripple, which leads to decreased beam acceptance. The low-frequency tracking error of the excitation current would affect the matching degree of magnetic field and beam energy, which would cause the closed orbit distortion of the beam. The correlation between magnetic field ripple and excitation current ripple of HIAF BRing dipole magnet is studied in this paper. The current quality quantification methods based on high and low-frequency separation are proposed, which evaluate the effect of excitation current error on the beam. The low-frequency tracking error and high-frequency ripple error of the excitation current are obtained by Gaussian smoothing. Three times the standard deviation is used as the quantification indicator of the excitation current in terms of ripple and tracking error. Since parameters of the low-pass filter are determined by the response relationship between magnetic field ripple and excitation current ripple, this method could accurately quantify the magnetic field ripple. Th current tracking error waveform could be used to adjust the reference waveform of synchrotron pulse power supplies, improving the matching degree of magnetic field and beam energy.

In recent years, off-axis injection schemes based on nonlinear kicker magnets have emerged as a new research focus, particularly suitable for storage rings with small dynamic apertures. This scheme is characterized by a strong magnetic field generated by the nonlinear kicker magnet at the injection point to deflect the injected beam, while maintaining a near-zero magnetic field near the central orbit, significantly reducing interference with the stored beam. This paper presents the design of a nonlinear kicker magnet with an eight-conductor layout, conducting an in-depth study on the impact of key parameters—such as conductor layout, edge fields at the magnet ends, and ceramic vacuum coatings—on magnetic field performance, followed by optimization of these parameters. Results indicate that this nonlinear kicker magnet design meets the injection system requirements for the high-brightness electron-positron collider and synchrotron radiation ring under development.

High-power ytterbium-doped fiber lasers have a wide range of applications in the maintenance of nuclear facilities owing to the advantages of high power, high efficiency, and flexible transmission. However, the irradiation effect in the nuclear facility environment can decrease the power of the fiber laser, which poses a big challenge to applications in such scenarios. Considering the self-bleaching effect of fiber lasers, we explore the relationship between darkening and self-bleaching effect under different irradiation dose rates. When the irradiation dose rate is relatively low, such as 0.1 rad/s, the output power of the 1 kW fiber laser is quite stable with the power fluctuation less than 1.79% during the whole experiment. We name such phenomenon as the self-bleaching and radiation equilibrium (SBRE). It is verified for the first time that under a certain irradiation dose rate, the laser power enhancement caused by the self-bleaching effect of the fiber laser can balance the power decrease caused by the irradiation effect, which provides effective support for the design of fiber lasers in related applications.

The radiation experiment on the seed stage of narrow line-width fiber lasers by γ ray radiation with total dose of 50 krad(Si) is conducted. The output properties of this seed laser are analyzed before and after γ radiation. Experimental results reveal that the output power declines over 70%, and the temperature of gain fiber rises significantly as the loss increases. The radiated seed source is amplified to kW power level, presenting little change of output power, central wavelength, and 3 dB bandwidth at different radiation dose. However, the SRS suppression slightly decreased with the increase of radiation dose. 793 nm and 524 nm LDs with the same power are applied as bleaching sources of radiated seed stage, and the bleaching effect is analyzed. Due to higher photon energy and closer to the absorption peak of radiation-induced defects, 524 nm LD presents a better bleaching effect. The output power of seed stage and 793 nm bleaching duration presents a linear relationship with a bleaching speed at 0.30 W/h, and the output power and 524 nm bleaching duration approximately presents a tensile-exponential function relationship with a bleaching speed at 1.65 W/h.

In 1D particle-in-cell (PIC) simulation, it is found that a plasma grating is produced by the interaction of a single ultra-short laser pulse with a solid-density plasma carbon target. When the appropriate laser and plasma parameters are used, the incident laser and the laser reflected by the rear-surface of the plasma target can form a standing wave, resulting in a ponderomotive force and charge-separation field that can modulate the plasma density and form a plasma density grating. Under this mechanism, we have studied the plasma density gratings generated by the interaction between plasma and ultraviolet laser pulses with wavelengths ranging from 40nm to 130 nm. The results show that, using a single laser pulse and a under-critical plasma target, stable plasma gratings can last more than several tens of picoseconds, with the max peak density greater than twenty times that of the initial density. Compared with traditional generation of plasma gratings with two laser beams or density-gradient plasmas, this scheme with uniform plasma is easier to carry out.

In vacuum and space environment, laser damage resistance of the optical film reduces greatly. This is mainly due to the coupling effect of organic pollution in the vacuum environment and the internal defect of the film, which results in the enhancement of the light field of film. The protective film technology is an effective measure to improve the ability of optical film to resist laser damage. Based on the finite-difference time-domain algorithm, the inhibition effect of the protective layer on the light field enhancement induced by the coupling of organic pollution droplet and defect was analyzed. The analysis result shows that the light field peak value of TiO2 film decreases with the increase of protective layer thickness. When the refractive index of the protective layer is the middle value of the organic pollution droplet refractive index and that of the film , the inhibition effect of light field enhancement is the greatest. The experimental results have verified the theoretical analysis. This study deepens the understanding of the mechanism of laser induced damage degradation of optical film in vacuum and has certain reference value for improving the laser damage resistance of optical film in vacuum environment.

To enhance the protective effectiveness of the Beidou Navigation Satellite System (BDS) and the Global Positioning System (GPS) against high-power microwave, we adopted the method of field-circuit collaborative simulation design to analyze the response characteristics of the BDS/GPS antenna under high-power microwave irradiation. The coupling voltage was obtained by simulation. To achieve protection against high-power microwave, a two-stage protection circuit was designed. By constructing steady-state and transient circuit models, the insertion loss and leakage voltage were analyzed according to simulation, and the circuit was processed. The test results show that the leakage power of the protective circuit was less than 0.5 W under HPM-NS injection of 2 kW, the leakage voltage was less than 12 V under HPM-UWS injection of 1 411 V, and this proposed circuit structure can achieve effective suppression of high-power microwave. The protection circuit was assembled into the BDS/GPS antenna, and the test results show that the navigation systems can operate normally.

The influence of boundary deformation on the resonant frequency drift of a reverberation chamber was analyzed, and a design of a reverberation chamber reflector with controllable boundary deformation was proposed. Transforming the traditional mechanical stirrer into a wrinkled wall, the goal is to change the boundary conditions by controlling the angle between adjacent reflection modules. A simulation model of a 5 m×4 m×3 m reverberation chamber was constructed, and the effectiveness of the controllable boundary deformation reverberation chamber was analyzed from three aspects: field uniformity, stirring efficiency, and field distribution. The results show that the standard deviation of the electric field in the test area was less than 3 dB, the stirring efficiency was higher than that of traditional mechanical mixers, and the electric field in the test area followed the ideal distribution pattern of the reverberation chamber. This method can effectively increase the testing area space of the reverberation chamber.

Aiming to address the bottleneck of low output power in terahertz band traveling wave tubes and responding to the distinct demand for compact design, this paper proposes a 0.34 THz folded waveguide traveling wave tube structure with power combination inside the tube. Firstly, the high-frequency characteristics of the folded waveguide slow-wave structure are investigated. Electromagnetic full-wave simulations are used to obtain its dispersion characteristics and coupling impedance. The normalized phase velocity at 0.34 THz is 0.248 and the coupling impedance is 0.46 Ω. Secondly, a 3 dB directional coupler structure for in-tube power combination is designed. The analysis indicates that its amplitude balance is within ±0.19 dB in the range of 0.31–0.368 THz, and the isolation exceeds 24 dB. Finally, the basic structure of the folded waveguide traveling wave tube based on the in-tube combination of the 3 dB directional coupler is demonstrated. The simulation model is constructed, and the results show a maximum output power of 9.16 W, a gain of 26.6 dB, and a 3 dB bandwidth of 21 GHz. For comparison, the output power of a single folded waveguide traveling wave tube is 6.18 W. The output power of the in-tube synthesized folded waveguide traveling wave tube is 1.48 times that of the single traveling wave tube. Moreover, compared with the design of a dual-tube assembly using conventional external power combination structure, the lateral size is reduced by at least 56.5%.

In this paper, the electron optical system for 140 GHz folded waveguide travelling wave tube (FTWT) is designed. The electron beam considering the thermal velocity effect in periodic permanent magnetic (PPM) focusing system is simulated and optimized by using the particle simulation software Opera-3D. The magnetic field is optimized to improve the matching effect between electron beam and PPM. The current of electron optical system is 60 mA when the anode voltage is 20 kV, and the simulation shows that the transmission efficiency is improved to 99.9%. In the experiment of sample tube, the parameters of the electron gun are in agreement with the design results. When the travelling wave tube (TWT) works in DC mode, about 97.2% of the electron beam reaches the collector.

The power division network is one of the key components of high power microwave (HPM) phased array antenna. It is used to divide HPM into several paths and feed them into phase shifter and element antenna. In such a network, the over-mode circular waveguide to multi-channel rectangular waveguide power divider has the function of mode conversion and power distribution. It is the front end of the power division network and requires high power handling capability, high transmission efficiency and low reflection. In this paper, the design, simulation, fabrication, and small signal test of the power divider from Ku-band GW-level over-mode circular waveguide to 8-channel rectangular waveguide were carried out. Subsequently, the power handling capacity of the power divider was evaluated utilizing the established power capacity testing facility. The experimental outcomes demonstrated that within the frequency band of 14.7 GHz±200 MHz, the reflection coefficient was consistently below -20 dB, the transmission coefficient exceeded -9.1 dB, the port imbalance was maintained at less the 0.4 dB, and the power handling capacity exceeded 900 MW.

The study of measurement methods for strong electric fields in small spaces is a challenge. By utilizing the Stark effect of spectral lines and selecting reasonable atoms or ions, measurements can be completed without interference. This article designs a set of atmospheric pressure nanosecond pulse discharge experimental device, which generates a strong electric field through needle electrode discharge, and tests the splitting of He 447.1nm spectral lines under strong electric fields generated at different discharge voltages. When the spectral line broadening is difficult to obtain directly by observing the spectral line, by using the non-linear least squares, the allowable component, the prohibited component and the field independent component of the spectral line are analyzed and the corresponding wavelength offset is calculated to obtain the electric field size. According to Mason’s formula, based on energy equivalence, the experimental results meet theoretical expectations, and this method can be used to measure strong electric fields in small spaces. Analysis indicates that the discrepancy between theoretical and experimental results may be attributed to the shielding effect caused by the plasma produced when helium gas undergoes breakdown.

In experimental validations of fusion blanket neutronics performance, tritium production rate is one of the most crucial measurement parameters. The number of 6Li atoms in the detector, as a normalization factor for calculating the tritium production rate, is a key factor determining the accuracy of measurement results and must be accurately calibrated. This paper specifically introduces the principles of calibrating the number of 6Li, the experimental setup and procedure, and the methods for quantifying uncertainties. For the first time, the number of 6Li atoms in a small lithium glass detector was calibrated using a germanium monocrystal monochromator to obtain 32.36 meV neutrons at the M5 horizontal channel of the China Mianyang Research Reactor (CMRR), with an uncertainty of 2.62%.

To enhance the corrosion resistance of depleted uranium surfaces, a comparative analysis was conducted to evaluate the efficacy of three plasma nitriding technologies: Plasma Source Ion Implantation (PSII), Glow Discharge Plasma Nitriding (GDPN), and Hollow Cathode Plasma Nitriding (GDPN). The composition, structure and chemical state of the nitrided layers were analysed using a range of material analysis methods. The nitrides present in the three nitrided layers are predominantly α-U2N3. Due to the strong affinity between uranium metal and oxygen, all three plasma nitriding processes have introduced oxygen impurities to varying degrees. PSII is capable of breaking through the thermodynamic equilibrium and converting some of the oxides into nitrides, while GDPN and HCPN can form nitrides through surface reactions and thermal diffusion. HCPN technology has certain advantages in controlling the oxygen impurities, and can significantly reduce the oxygen impurities in the nitrided layer. The results of the wet heat corrosion and electrochemical tests demonstrate that plasma nitriding can markedly enhance the corrosion resistance of depleted uranium. The degree of improvement achieved by HCPN and GDPN is superior to that of PSII, with HCPN technology exhibiting the most favourable outcome. The findings of this study could provide a reference for plasma nitriding treatment of reactive metals..

In the field of neutron radiation, the problem of neutron spectrum unfolding has attracted much attention. The Bonner sphere spectrometer is often used for neutron spectrum detection, and the maximum entropy method can be used to analyze the neutron spectrum of the Bonner sphere spectrometer. Based on this principle, this paper establishes a simulation model including the Bonner sphere spectrometer with reference to the neutron shielding experiment in 2014. The simulation results of Monte Carlo method are used as the prior spectrum, and the maximum entropy deconvolution code (MAXED) based on the principle of maximum entropy is used for neutron spectrum unfolding. The effectiveness and accuracy of the method are verified by comparing with the literature data. By increasing the number of random particles in Monte Carlo method, multiple groups of prior spectrum with different accuracy are obtained. For different prior spectrum, the final spectral solution results can be statistically significant and the spectral solution results are effective. After comparison, the more accurate the prior spectrum is, the higher the accuracy of the final spectral solution results, indicating that it is important to obtain accurate Monte Carlo calculation results through appropriate variance reduction method, which can provide reference for subsequent research and experiments. In this paper, the GRAVEL method based on iterative algorithm is used to solve the neutron spectrum simultaneously, and the comparison of the calculation results of the two methods further proves the superior performance of the solution spectrum of the MAXED method.

In nuclear radiation environment, the radiation protection of vehicles such as ships and tanks is crucial for nuclear safety, radiation protection, radiation damage assessment, response and decision-making. This paper does research on ships’ radiation shielding performance. Using ship materials and typical structures, neutron-photon coupling transportation method is adopted to quantitatively simulate ship’s radiation shielding performance, under neutron and γ’ simultaneous irradiation. By utilizing large-scale parallel technology, efficient simulation has been achieved for deep-penetrating problem. The simulation of radiation transportation process considers incident neutrons, γ and even secondary particles. For basic shape models such as plate, cavity with different thicknesses and materials, it simulates neutron and γ's transportation in gas and materials, monitors particles flux, dose, and energy spectrum. The radiation protection factors(RPF) for neutrons, γ rays, and both are simulated and analyzed. It studies RPF influence rules with key parameter such as plate thicknesses, incident angles. The materials researched include Fe, Al, Pb, HSLA100 steel, and the radiation sources include single energy neutron, and nuclear leaked neutron and γ spectra. These results will contribute to the analysis of vehicles’ radiation protection performance, and provide theoretical support for nuclear radiation effect assessment, emergency response, etc.

This article employs Fourier transform infrared spectroscopy to investigate radiometric calibration methods and the measurement of continuous atmospheric transmittance across the shortwave infrared band. The presence of multiple strong absorption bands within the shortwave infrared spectrum (0.9-2.2 μm) leads to significant errors in the commonly used Langley method, and even the improved Langley method struggles to yield accurate results for the calibration of these strong absorption bands. To fulfill the high-precision measurement demands for atmospheric transmittance across the entire shortwave infrared band, this paper introduces an enhanced method for calculating atmospheric transmittance. Initially, the Langley calibration technique is utilized to determine the instrument calibration value and response function K in the non-absorption band. Subsequently, the instrument response function in the absorption band is derived by interpolating the wavelength based on the instrument response function calibrated in the non-absorption band. Ultimately, the instrument calibration value is established by correlating it with the solar irradiance at the atmosphere’s top, thereby obtaining the atmospheric transmittance across the entire shortwave infrared band. Compared to results calculated by the medium-resolution atmospheric radiative transfer model software CART, the atmospheric transmittance values obtained using this method within the 0.9-2.2 μm band exhibit an average error of less than 2.5%.

To improve the radiation measurement efficiency of nuclear retirement facilities and reduce the risk of radiation exposure to measurement personnel, a radiation patrol control system for multiple unmanned vehicle formations has been designed. Firstly, the navigation following formation strategy is adopted to control the robots to move in a predetermined formation, while collecting real-time radiation intensity information and their respective position data measured by each unmanned vehicle during the formation process, to preliminarily analyze the radiation distribution inside the environment. Secondly, utilizing radiation intensity and location information, the Markov chain Monte Carlo method is employed to estimate the parameters of the radiation source. The simulation results show that the unmanned vehicle formation can move along the automatically planned path in radiation environment, with advantages such as fast response speed, high control accuracy, and it can estimate the parameters of the radiation source position coordinates.