With the popularization of intelligent mobile phones, their wireless communication modules generate intentional and unintentional radiation that may interfere with radio telescopes. Tests in an anechoic chamber show that mobile phone radiation at and around the observatory site exceeds the telescope protection limits, affecting normal astronomical observations. Accordingly, this paper proposes management and shielding measures to mitigate such interference. (Abstract)

The combination of high/low atomic number metal materials have been proved to be effective in electron radiation shielding, however, the detailed microstructure transformation of them after high-energy electron beam radiation is still worth further investigation. In this study, Al/Ta layered composite plate with 93.5% electronic shielding efficiency were successfully prepared via differential temperature rolling. The microstructural transformation of Al/Ta composite plates after being irradiated by 5 MeV electron beam was comprehensively investigated. Electron beam irradiation causes a decrease in dislocation density and a large number of voids generated around the precipitates and stacking faults as the main defects in AA2A12. The precipitate/matrix boundary and stacking fault are effective sinks for radiation-induced vacancies due to higher strain energy. Electron irradiation effectively activates the raw dislocations in Al and promotes the reduction of geometrically necessary dislocation densities and the subsequent recrystallization process, which is most pronounced near the Al/Ta interface. In contrast, Ta alloy exhibits high radiation stability as no visible cavities or other microstructural changes can be observed. Electron irradiation promotes the formation of extra intermetallic compounds at the Al/Ta interface, which is attributed to the increased diffusion rate of solute atoms caused by irradiation-induced defects. After electron irradiation, the reduced dislocation density in Al leads to diminished work-hardening effect, resulting in decreased hardness of Al matrix, which is not significant in Ta.

To improve the computational efficiency of nearfield electromagnetic coupling in parabolic antennas for radio telescope Electromagnetic Compatibility (EMC) design, this paper develops a calculation program based on the Physical Optics ($P O$) method. Using a standard 26 m Cassegrain antenna, the coupling response within a 40 m region from 1.03 GHz to 1.7 GHz is calculated and analyzed. Compared with simulation software, the program achieves errors of approximately 10 dB at low frequencies and $\mathbf{5 d B}$ at high frequencies, while improving efficiency by about 50 times. This provides technical support for large-scale near-field electromagnetic coupling computations.

To meet requirements such as heat dissipation, power supply, and data transmission, metal shields often require aperture structures. These apertures reduce shielding effectiveness and increase the difficulty of electromagnetic analysis. Current numerical methods are usually computationally expensive, while analytical methods offer high efficiency. Therefore, this paper focuses on a rectangular shielding cavity coupled with an external waveguide. An electromagnetic field model is established based on dyadic Green's functions and aperture coupling theory. An analytical calculation method for the shielding effectiveness of the apertured cavity is proposed. Simulation results show that the proposed method ensures computational accuracy while significantly reducing reliance on full-wave simulation and improving computational efficiency. This study can provide theoretical reference for the design of shielding structures.

The shielding efficiency, mechanical property, interfacial bonding strength and microstructure of the laminated AA2024/RO5252 and AA2024/AA1060/RO5252 composites produced by differential temperature rolling, followed by solution treatment at 500 degrees C for 1.5 h and aging at 200 degrees C for 8 h, were investigated by total dose radiation tests, tensile tests, shear tests, scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) techniques. Both composites showed excellent radiation shielding effect, which were similar to 60 % higher than that of single AA2024 plate that had almost the same surface density. The tensile test and shear test results showed that the yield strength, tensile strength, elongation and interfacial bonding strength of two-layer and three-layer composites in the aged state were 364 +/- 1 MPa, 476 +/- 1 MPa, 14 +/- 2 %, 84 +/- 1 MPa and 353 +/- 1 MPa, 451 +/- 1 MPa, 11 +/- 1 %, 54 +/- 1 MPa, respectively. The SEM observations of the shear fracture surface demonstrated a clear increase in the residual aluminum area on the RO5252 side after heat treatment in the two composites. The EBSD results for the cross section of interface showed that after rolling, the RO5252 layer was deformed, while the AA2024 layer was in a state between recovery and recrystallization. After heat treatment, the RO5252 layer remained deformed, while the AA2024 layer underwent a complete recrystallization process. The SEM and TEM observations showed separate Al3339.8Cu231.95Ta2336 intermetallic compound particles at the interface of two-layer composites. But for the three-layer composites, no intermetallic compounds were observed, which is beneficial for improving the property of thermal cycling. These results provide important information for developing laminated Al/Ta based alloy composite material.

This study investigates interference mitigation for mobile communication services in the vicinity of large radio telescopes. A power level function for communication interference reaching the telescope and a coverage function for communication base stations are established to minimize both the impact on network coverage and the received interference power at the telescope. A multi-objective genetic algorithm optimization is applied to optimize the azimuth and elevation angles of base station antennas. The results demonstrate that while sacrificing only 1% of network coverage, the interference power can be significantly reduced by approximately 12.2 dB. The proposed methodology can be applied to suppress electromagnetic interference sources around radio astronomy sites, ensuring electromagnetic compatibility between radio astronomy operations and other wireless services.

Deep dielectric charging and discharging by electrons has been known for years. However, deep space missions towards the Moon, Mars and Jupiter have developed these years. In these space environments, spacecrafts would expose in high fluxes of solar energetic protons which demands the understanding of charging and discharging mechanism by protons. In this paper, dielectric breakdown of polyimide(PI) material irradiated by 40 MeV-protons was studied. Discharge of PI materials with different thicknesses of 21.5 mm, 15.5 mm, 13.6 mm and 8.2 mm were investigated. For PI films with thickness of 21.5 mm, 15.5 mm, and 13.6 mm, proton discharges were firstly triggered as the protons reached integral fluxes of 1.2x 10 12 p/cm2, 2.7 x 10 12 p/cm2 and 1.2x 10 12 p/cm2, respectively. No discharge was achieved for PI film with 8.2 mm thickness. Besides, discharge events originated by secondary electrons were also achieved during irradiation. On the other hand, the internal potential and electric field was also simulated using simulation of internal charging software for 3D (SIC3D). Simulation results indicate that discharge threshold caused by protons is decided by two factors: the internal electric field and the length of discharge path. After irradiated by protons, a thicker material might store more protons and produce stronger internal electric field, but might also has a longer discharge path. The integral proton flux required for discharging was 10 12 p/cm2 which is extremely high in real space conditions, and proton discharge may not happen immediately after irradiated by energetic protons in space. But the stored protons can produce a localized electric field and might be triggered during the next space radiation events like the solar energetic particle (SEP) events or the bursts of energetic electrons (BEE) events.

To investigate the impact of broadband Radio Frequency Interference (BB-RFI) on radio astronomical observations, we acquired high-time-resolution spectral data in the L-band using the 26-meter radio telescope at Nanshan Observatory. The BB-RFIs and their characteristics were identified and extracted based on the asymmetriclly reweighted penalized least squares (arPLS) and Qn estimate algorithms. We further counted the characteristics of the BB-RFIs. The results show that the BB-RFIs’ bandwidth range from 290 MHz to 1000 MHz, with a predominant concentration between 300 MHz and 500 MHz, and the BB-RFIs mainly include single, clustered, and periodic signals. Additionally, The BB-RFIs exhibit a relatively uniform spatial distribution in the temporal distribution, and the occurrence of BB-RFIs is significantly higher in the morning than in the afternoon and evening within a day, correlating with the working patterns of personnel around the observatory. The preliminary analysis provides a foundation for further research on BB-RFI mitigation strategies in radio astronomy.

The radiation environment around Jupiter is more severe than that in medium-to-high Earth orbits. Traditional shielding materials have significant mass and cost, making it imperative to design more efficient shielding materials to counteract the harmful effects of intense radiation. This paper uses the Tianwen-4 orbiter’s orbit around Jupiter as a case study, using the D&G83+Salammbo model to calculate the high-energy particle radiation environment of the Jovian system. The Geant4 tool was utilized to simulate the shielding performance of “high$\mathbf{Z}+$ low- $\mathbf{Z}^{\prime \prime}$ composite materials, analyzing their shielding effectiveness at equivalent thicknesses ranging from 3 mm to 100 mm. The research results indicate that aluminium-tantalum composite materials exhibit a significant radiation protection effect compared to elemental aluminium, with a 54.92% improvement in shielding performance at an equivalent thickness of 20 mm. Furthermore, as theequivalent thickness increases, the proportion of aluminium in the optimal composite shielding layer gradually increases. These findings provide an important reference for the design and application of radiation protection materials in future deep-space exploration missions.

As the research work about irradiation effect and neutron measurement requires high-energy neutron with the development in the fields of space exploration, medical treatment and high-energy physics investigation, a beamline of quasi-monoenergetic neutron in the range of 30 similar to 50 MeV based on a proton cyclotron with a maximum energy of 50 MeV is under construction and preparation. We studied the design of this quasi-monoenergetic neutron beamline with a focus on target chamber and collimator. Comprehensive comparison on characters of thermodynamic and nuclear physics between lithium and beryllium was conducted, and lithium was chosen as target material by better performance on quasi-monoenergetic neutron peak. Relevant parametric simulations of lithium thickness were carried out in consideration of efficiency and quality of neutron generation which shows the change on height and width of quasi-monoenergetic neutron peak. Energy loss of incident proton caused by titanium film and argon gas was estimated to provide a reference for the mechanical design of target chamber. Evaluation has been done to show the variation of neutron spectra and fluxes at different positions from the target along with collimators of different lengths, and the collimator length was determined to be 2 m in view of flux and ratio of quasi-monoenergetic neutron peak. All work provides a data reference for the building and operation of the quasi-monoenergetic neutron beamline.

With China's lunar exploration program steadily advancing from the landmark orbiting missions of Chang'e-1 to the historic sample-return feats of Chang'e-5 and the groundbreaking far-side landing of Chang'e-4,China has entered a critical phase of deepening lunar exploration,including preparations for crewed lunar missions.Among these ambitious endeavors,identifying and mitigating potential operational risks is crucial to ensuring the success of these ambitious efforts.This work focuses on a critical hazard unique to China's lunar surface exploration efforts:the triboelectric charging and discharging phenomenon between lunar rover wheels and lunar dust,which has a significant impact on astronaut safety and the reliability of onboard electronic systems. Lunar surface missions will face the risk of triboelectric charging and discharging resulting from friction between lunar rover wheels and lunar dust.Preliminary theoretical studies indicate that metal wheels may become charged to a level of approximately-5000 V,with discharge pulse currents reaching an order of magnitude of 0.1 A,posing a severe threat to astronaut safety and the normal operation of device circuits. This paper employs ground-based experimental methods to investigate the triboelectric charging and discharging risks of lunar rover wheels in vacuum and simulated solar wind plasma environments.The research findings are given below. In a vacuum environment,when an aluminum alloy lunar rover wheel(136 mm in diameter)travels on a lunar dust layer at a speed of 0.003 m/s,it rapidly charges to a positive potential of several hundred volts.Discharge breakdown occurs when the wheel travels approximately 20 m and reaches a potential of 550 V.At this point,the captured discharge current pulse amplitude can reach 1.5 A,with a pulse duration of about 100 ns.Increasing the friction frequency significantly accelerates the charging rate and leads to more frequent discharges. In a simulated solar wind plasma environment,when the wheel travels at 0.003 m/s,the combined effect of the environment and friction results in a negative charging potential.After reaching equilibrium,the potential stabilizes at approximately-830 V,and discharges occur more frequently than in a vacuum environment.Discharge breakdown takes place when the wheel travels just 8.5 m,with the discharge current pulse amplitude reaching up to 0.3 A and a pulse duration of 100 ns. These discharge pulses cause electromagnetic interference to linear circuits,leading to abnormal output of voltage signals in subsequent modes.The abnormal signals have an amplitude on the order of 10 V and a duration of 29 ms. This study confirms that the risk of triboelectric charging and discharging in lunar rovers is relatively high.Although theoretical models predict that the lunar roving vehicle(LRV)would experience rapid dissipation of triboelectric charges(with no charging/discharging risk)when operating at 0.03 m/s,the experiments show that even at a slow speed of 0.003 m/s,the wheels still accumulate charges and experience frequent discharge breakdowns.The amplitude of discharge pulse can reach the level of 1 ampere,causing significant electromagnetic interference to nearby circuits.Clearly,theoretical models underestimate the risk of triboelectric charging and discharging in lunar surface environments.It is recommended that future engineering tasks pay close attention to this issue and further evaluate the extent of its hazards.

In practical shielding engineering, apertures and seams on the surface of shielding enclosures are prone to electromagnetic leakage, which can be effectively mitigated by installing EMI gaskets. To analyze the influence of gasket dimensions on shielding effectiveness and support electromagnetic shielding design, this study employs isotropic materials to fill regular gaps, establishing an analytical model to evaluate the impact of gasket size. The shielding effectiveness of gaskets with dimensions ranging from 1 mm to 10 mm is calculated and analyzed. The findings indicate that smaller gasket sizes result in higher shielding effectiveness. Therefore, in practical electromagnetic shielding design, selecting smaller gaskets—while ensuring basic functionality and reliability—can enhance the overall shielding performance of the product.

For large diameter radio telescope construction, it is essential to suppress radio frequency interference from various equipment. Considering that some electronic devices have extremely high electromagnetic compatibility (EMC) requirements and are characterized by compact size and high integration, their EMC control poses significant technical challenges. To address these issues, this paper investigated the technical challenges involved in the EMC control process and performance measurement of small electronic devices. Based on the electromagnetic leakage mechanism of shielding protection and drawing upon engineering experience, a solution was proposed to replace the original shielding enclosure with an interface conversion board, and the window testing method was employed to measure the shielding effectiveness, resolving the technical issue of measuring the shielding performance of small-scale shielding enclosures. Furthermore, this methodology was applied to the EMC control process of actuators, such as EMC design, performance measurement, and optimization, which successfully addressed the EMC issues. The proposed method has further upgraded the EMC control process for large radio telescopes, effectively solving the EMC challenges posed by small electronic devices during the construction and operation of the telescope.

Servo drives are widely used in radio telescope driving systems, yet their power switching devices generate broadband electromagnetic interference due to high-frequency switching characteristics, which adversely affects astronomical observations. This study addresses this issue by employing near-field diagnostic method in an anechoic chamber to analysis the radiation characteristics of critical drive modules, identifying core interference sources through a radiation threshold evaluation model. Experimental results demonstrate that the radiation intensity from inverter circuits significantly exceeds that of rectifier and filter modules, with peak radiation levels surpassing the threshold by about 35 dB. Accordingly, both module-level and system-level electromagnetic protection schemes are proposed. The research results provide theoretical foundations and practical references for electromagnetic shielding design in high-power radio telescope servo control systems.

China's lunar exploration, including Chang'e-6, aims for future manned missions and a research station. The lunar environment and human activity, such as friction between rovers, spacesuits, and lunar dust, pose serious charging hazards, potentially generating voltages in the kilovolt range. This paper investigates the frictional charging effects between materials and simulated lunar dust under vacuum, UV light, and varying temperatures. Experimental results show that Teflon can be charged to-375 V in vacuum,-200 V under UV light, and-39 V in the atmosphere. Triboelectrification at different temperatures reveals the most severe charging occurs at-50 degrees C, reaching-1975 V. These findings provide insights into potential charge and discharge risks for future lunar missions.

In order to solve the coupling problem of the wideband dual-polarization array of MIMO antennas, a decoupling method combining wideband array-antenna decoupling surface (WADS) and cross-type dielectric resonator is proposed, and the decoupling design is verified by simulation of $2 \times1$ compact wideband dual-polarization array antenna. According to the simulation results, the E-plane coupling is increased from -17dB to -22dB, and the H-plane coupling is increased from -18 dB to -25 dB in the 2.1-3 GHz operating frequency band, and the antenna array with decoupling structure still has good radiation characteristics. The decoupling method proposed in this paper has great application potential for broadband dual-polarization base station arrays in 5 G systems.

To efficiently analyze and evaluate the effect of radiation sources around the station site on astronomical observations, a method to quantify the interference level threshold of station site regionalization is proposed. A terrain model of the station site is established and meshed, and an efficient grid retrieval algorithm is used to extract relative terrain data from any position (grid) within the station site area. Based on this, a radio propagation algorithm adapted to the topographic characteristics of the station site is selected to calculate the radio propagation loss from any location of the station site to the telescope. Considering the interference level limit and side lobe gain of the telescope feed interface, a threshold quantization of the interference level in the station site area is implemented. This approach is then applied to the QTT (QiTai Radio Telescope) station site, providing important technical support for electromagnetic compatibility measurement of the radio telescope, radio management of the station site, and interference mitigation strategy.

AbstractTaiji is proposed as a space‐based gravitational wave (GW) observatory consisting of three spacecraft in a heliocentric orbit meanwhile with the distance of 3 million kilometers ahead of the Earth at about 20°. Free‐falling test masses (TMs) are a key component of the interferometer for space‐based GW detection in the 0.1mHz–1 Hz frequency range. Exposure to energetic particles in the space environment can lead to charging of the TMs and thus cause additional electrostatic forces and Lorentz forces that limit the sensitivity of the interferometer and may affect the quality of the scientific data. This study aims to model the charging of TMs during Galactic cosmic rays and solar proton events (SPEs) using the Monte Carlo simulation toolkit meanwhile with constructing the sophisticated 3D spacecraft. The results show that the total net charging rates are 34.48 +e/s and 33.85 +e/s on TM1 and TM2 during the solar minimum, and 9.58 +e/s on TM1 and 9.65 +e/s on TM2 during the solar maximum. We confirm that no matter for solar minimum or solar maximum, protons contribute to the largest proportion of the TMs charging rate. Furthermore, charging for five typical SPEs is also investigated, and the maximum TMs charging rate reaches 76,674 +e/s, indicating that sporadic SPEs have a high risk for TMs charging. Finally, the charging rates of a TM imitation are tested on ground by the 30–50 MeV proton irradiation experiment, and the experimental results show good consistence with the simulation results with the error <10%.

Radiation environments such as galactic cosmic rays，solar cosmic rays and radiation belts produce various space radiation effects on the components and astronauts，threaten the normal operation of spacecraft and life and health of astronauts. Material shielding is currently one of the most effective radiation protection measures and plays an important role in ensuring the smooth progress of aerospace missions. The research progress of space radiation shielding materials in different scenarios for three typical objects：components，astronauts，and aircraft platform protection is reviewed in this paper. Also the development direction of space radiation shielding materials such as metal composite materials and polymer materials is explored.

Unlike the Earth, the Moon lacks is not protected from the atmosphere and global magnetic field, and will be directly exposed to complex radiation environments such as high-energy cosmic rays, solar wind, and the Earth’s magnetotail plasma. The surface of the Moon is covered with a thick layer of lunar soil, and the particles in the soil with a diameter between 30 nm–20 μm are called lunar dust. In the complex environments such as solar wind or magnetotail plasma, lunar dust carries an electric charge and becomes charged lunar dust. Charged lunar dust is prone to migration under the action of the electric field on the lunar surface. Charged migrated lunar dust is easy to adhere to the surface of instruments and equipment, resulting in visual impairment, astronauts’ movement disorders, equipment mechanical blockage, sealing failure, and material wear, which affects the lunar exploration mission. As an important lunar exploration landing site, the lunar south pole receives special solar radiation and produces a special dust plasma environment due to its special location. In order to provide an environmental reference for lunar south pole exploration, it is necessary to explore the characteristics of the dust plasma environment in the lunar south pole and its impact. In view of the lunar south pole environment, The Spacecraft Plasma Interactions Software (SPIS) software developed by the European Space Agency is used to carry out modelling and simulation in this work. Through the simulation, the logarithmic distribution of the lunar dust space density in a range of 0–200 m at the lunar south pole, the potential distribution near the lunar surface, and the spatial distribution characteristics of plasma electrons and ions are obtained. The obtained lunar dust space density and lunar surface potential are similar to the previous theoretical derivation and field detection data, so the simulation results have high reliability. The spatial potential distribution and the spatial density distribution of electrons and ions in the lunar environment with and without lunar dust are compared. Finally, the conclusions can be drawn as follows. The space potential increases with altitude increasing. The potential at 0–10 m near the lunar south pole is about –40 V, and the space potential at 100 m is about –20 V. The density of lunar dust in an altitude range below 10 m is 107.22 m–3–104.66 m–3. The electron density in the dust plasma near the lunar surface is 105.47 m–3, and the ion density is 106.07 m–3, and both increase with altitude increasing. Charged lunar dust affects the spatial distribution of lunar dust, mainly through affecting the distribution of the space electric field, which leads to difference in electron distribution, but has little effect on ions.