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40 results on '"He, Chaoxiong"'

1. Investigating and Controlling the Libration and Rotation Dynamics of Nanoparticles in an Optomechanical System

Author

He, Chaoxiong, Wang, Jinchuan, Dong, Ying, Zhu, Shaochong, Ying, Qianwen, Ma, Yuanyuan, Feng, Fu, Yin, Zhangqi, Li, Cuihong, and Hu, Huizhu

Subjects
Physics - Optics
Abstract

In optomechanical systems, the libration and rotation of nanoparticles offer profound insights for ultrasensitive torque measurement and macroscopic quantum superpositions. Achievements include transitioning libration to rotation up to 6 GHz and cooling libration to millikelvin temperatures. It is undoubted that the libration and rotation are respectively driven by restoring and constant optical torques. The transition mechanisms between these two states, however, demand further exploration. In this perspective, it is demonstrated in this manuscript that monitoring lateral-scattered light allows real-time observation of libration/rotation transitions and associated hysteresis as ellipticities of trapping laser fields vary. By calculating optical torques and solving the Langevin equation, transitions are linked to the balance between anisotropic-polarization-induced sinusoidal optical torques and constant ones, with absorption identified as the main contributor to constant torques. These findings enable direct weak torque sensing and precise nanoparticle control in rotational degrees, paving the way for studying quantum effects like nonadiabatic phase shifts and macroscopic quantum superpositions, thereby enriching quantum optomechanics research.

Published
2024

2. Optically Levitated Nanoparticles as Receiving Antennas for Low Frequency Wireless Communication

Author

Fu, Zhenhai, Xu, Jinsheng, Zhu, Shaochong, He, Chaoxiong, Zhu, Xunming, Gao, Xiaowen, Cai, Han, He, Peitong, Chen, Zhiming, Zhang, Yizhou, Li, Nan, Chen, Xingfan, Dong, Ying, Zhu, Shiyao, Liu, Cheng, and Hu, Huizhu

Subjects
Physics - Applied Physics, Physics - Instrumentation and Detectors, Physics - Optics
Abstract

Low-frequency (LF) wireless communications play a crucial role in ensuring anti-interference, long-range, and efficient communication across various environments. However, in conventional LF communication systems, their antenna size is required to be inversely proportional to the wavelength, so that their mobility and flexibility are greatly limited. Here we introduce a novel prototype of LF receiving antennas based on optically levitated nanoparticles, which overcomes the size-frequency limitation to reduce the antenna size to the hundred-nanometer scale. These charged particles are extremely sensitive to external electric field as mechanical resonators, and their resonant frequencies are adjustable. The effectiveness of these antennas was experimentally demonstrated by using the frequency shift keying (2FSK) modulation scheme. The experimental results indicate a correlation between error rate and factors such as transmission rate, signal strength, and vacuum degree with a signal strength of approximately 0.1V/m and a bit error rate below 0.1%. This advancement in leveraging levitated particle mechanical resonators (LPMRs) as LF antennas marks a significant stride in long-distance communication technology.

Published
2024

5. A broadband and compact TE01 mode bend with hexagonal section for high-power microwave applications.

Author

Wang, Keqiang, Li, Hao, Li, Tianming, Wen, Guangjun, Wang, Haiyang, and He, Chaoxiong

Subjects
MODE-coupling theory (Phase transformations), MICROWAVES, PROBLEM solving, WAVELENGTHS, CURVATURE
Abstract

The conventional circular waveguide 90° TE01 bend makes it difficult to achieve broadband because of the serious interference from TM11 mode. To solve this problem, the mode coupling characteristics in the hexagonal waveguides are investigated in this paper, and it is found that when the deformation amplitude is appropriate, not only the degradation between TE01 and TM11 is broken but other parasitic modes can be efficiently suppressed. Based on the analysis, an oversized broadband TE01 waveguide bend with variable curvature is proposed, and its transmission efficiency is over 95% from 8.5 to 11 GHz, while its structure length is only 26.16 times wavelength. Measurement results indicate that the S21 of the bend is about −0.4 dB from 8.5 to 11 GHz, and it works stably under a microwave output power of 1 MW. The consistency between theoretical calculations, simulation, and experiments indicates the feasibility of this novel TE01 bend. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Theoretical and experimental investigations on a compact TE11 mode bend for high‐power transmission line.

Author

Wang, Keqiang, Li, Hao, Li, Tianming, and He, Chaoxiong

Subjects
ELECTRIC lines, POLARIZATION of electromagnetic waves, ELECTROMAGNETIC theory, ELECTROMAGNETIC waves, MODE-coupling theory (Phase transformations), WAVEGUIDES
Abstract

The oversized TE11 mode bend is able to make the transmission direction of electromagnetic wave to turn 90°, and it is one of the key components in the high‐power microwave system. The mode coupling characteristics between the TE11 and parasitic modes under two different polarisations in the bending waveguide are analysed, and it is found that the TE11 suffers less interferences from parasitic modes when its polarisation direction is perpendicular to the bending plane, and the corresponding 90° TE11 bend is easier to realise high performance. To verify this analysis, an oversized 90° TE11 bend waveguide working at 10 GHz is designed, and its structural length is only 7.5 times the central working wavelength. Simulated results indicate that its relative bandwidth is 15.6% when the transmission efficiency is over 98%, and its maximum power handling capacity reaches 5.6 GW at short microwave pulse duration (less than 100 ns). The S‐parameters indicate that its S21 is about −0.1 dB from 9.5 to 10.5 GHz, and its S11 is under −25 dB in the same frequency range. Meanwhile, the high power test indicates that the bend works stably when the injected power is 3 GW. [ABSTRACT FROM AUTHOR]

Published
2024
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13. Phase-Locked All-Cavity-Extraction Relativistic Magnetrons With Azimuth-Uniform Coupling Structure for Coherent Combining Applications

Author

Cheng, Renjie, Xiao, Renzhen, Li, Tianming, Wang, Jiaoyin, He, Chaoxiong, Wang, Haiyang, Li, Hao, Zhou, Yihong, Yang, Mingyu, Ou, Meiling, Chen, Tingxu, Ghannouchi, Fadhel M., and Hu, Biao

Abstract

An investigation on the phase locking of S-band relativistic magnetrons with an all-cavity-extraction (ACE-RM) structure is carried out. In order not to disrupt the periodic distribution of electric fields in the resonant cavities, an azimuth-uniform coupling structure is introduced, which could achieve a transmission efficiency of over 98% at the operating frequency, with an amplitude difference of only ±3.3%. Furthermore, particle-in-cell (PIC) simulations demonstrate that when five ACE RMs are interconnected through four such coupling structures, phase locking can be achieved, and the relative phase jitters are controlled within ±1%. After establishing stable $\pi $ -mode oscillation in RMs, in each of the 20 ports, an average output power of over 400 MW can be obtained, corresponding to a total power of 8.5 GW and a power conversion efficiency of 45%.

Published
2023
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14. Design of a Broad Bandwidth TM 01 Mode Waveguide Bend for High-Power Microwave Applications

Author

Wang, Keqiang, Zhang, Zhiqiang, Li, Hao, Luo, Yong, Li, Tianming, Wang, Haiyang, Zhou, Yihong, Hu, Biao, and He, Chaoxiong

Abstract

The TM 01 mode bend is a key component in the high-power microwave (HPM) transmission system. Based on the coupling wave theory and the deformation of the elliptical cross section, a novel broad bandwidth 90° TM 01 bend with an elliptical structure is proposed in this article. It is found that the interference modes can be effectively suppressed by controlling the variable curvature and cross Section deformation of the elliptical waveguide, and the bandwidth of the bend can be significantly improved. Numerical calculation and simulation results illustrate that the maximum transmission efficiency at the central frequency (9.7 GHz) is 99%, and its bandwidth reaches 4.37 GHz when the conversion efficiency exceeds 95%, which increases near 126.8% compared with the conventional circular design. The S-parameter experiment and high-power test are conducted by connecting them with a vector network analyzer (VNA) and an HPM source, respectively. Measurement results indicate that the S21 of the bend is about −0.5 dB in the frequency range of 8–11.25 GHz, and it works stably when the microwave power is 4 GW. The experimental results indicate that this TM 01 bend can be competently applied in the HPM system.

Published
2023
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24. Theoretical and Experimental Investigations on a 90° Compact TM 01 -TE 11 Mode Converter for RBWO.

Author

Wang, Keqiang, Zhang, Zhiqiang, Li, Hao, Luo, Yong, Li, Tianming, Wang, Haiyang, Zhou, Yihong, Hu, Biao, and He, Chaoxiong

Subjects
CIRCULAR waveguides, MICROWAVE devices, FREQUENCY changers, DC-to-DC converters
Abstract

Mode converter is one of the most important devices in the high-power microwave (HPM) applications. To conduct an in-depth research for the orthogonal mode converter, a novel 90° compact TM01-TE11 circular waveguide converter working at 9.7 GHz is proposed in this article. This design innovatively integrates the traditional mode converter with 90° bend techniques based on the mode coupling theory, which ensures a compact structure and high-power handling capacity. Calculated and simulated results illustrate that the maximum conversion efficiency of the converter at central frequency reaches 99.4% when the structure length is 535 mm, and the bandwidth reaches 680 MHz when the conversion efficiency exceeds 95%. For demonstration, a prototype is fabricated, and the corresponding experiments are investigated. According to the $S$ -parameter measurement, it has a high conversion efficiency at central frequency. Meanwhile, the high-power performance is conducted by connecting it with a relativistic backward oscillator (RBWO), and the converter works stably under a maximum output power of 4 GW. The good agreement of the theoretical analyses, simulations, and experimental results indicates the feasibility of the proposed converter. [ABSTRACT FROM AUTHOR]

Published
2022
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35. Preparation of Polyacrylate Hollow Microspheres via Facile Spray Drying

Author

He Chaoxiong, Tang Lei, Yuntao Li, Ye Nanbiao, Luyi Sun, Chen Pingxu, and Shuliang Li

Subjects
animal structures, Materials science, 02 engineering and technology, 010402 general chemistry, lcsh:Technology, 01 natural sciences, Microsphere, lcsh:Chemistry, General Materials Science, spray drying, lcsh:QH301-705.5, Instrumentation, Fluid Flow and Transfer Processes, chemistry.chemical_classification, Inlet temperature, polyacrylate, lcsh:T, Process Chemistry and Technology, digestive, oral, and skin physiology, technology, industry, and agriculture, General Engineering, Rotational speed, Polymer, equipment and supplies, 021001 nanoscience & nanotechnology, lcsh:QC1-999, 0104 chemical sciences, Computer Science Applications, lcsh:Biology (General), lcsh:QD1-999, chemistry, Chemical engineering, lcsh:TA1-2040, Spray drying, hollow microspheres, Particle size, lcsh:Engineering (General). Civil engineering (General), 0210 nano-technology, lcsh:Physics
Abstract

Polyacrylate microspheres with a hollow structure were prepared by a facile spray drying method. The effects of spray drying process parameters, including inlet temperature, atomizer rotational speed, and feed speed, on the particle size, bulk density, and morphology of the resultant polyacrylate hollow microspheres were investigated and discussed. The mechanism for the formation of the polyacrylate hollow microspheres was proposed. This facile and scalable method for preparing hollow polymer microspheres is expected to be valuable to prepare various polymer hollow structures for widespread application.

Published
2019

36. Compact L-Band Relativistic Magnetron With Diffraction Output of TEM Mode.

Author

He, Chaoxiong, Li, Tianming, Cheng, Renjie, Wang, Haiyang, Li, Hao, Zhou, Yihong, Wang, Keqiang, Ghannouchi, Fadhel M., and Hu, Biao

Subjects
*GYROTRONS, *MAGNETRONS, *SLOW wave structures, *CAVITY resonators, *PHASE velocity, *COMPACTING
Abstract

A compact L-band relativistic magnetron (RM) with the diffraction output (DO) of the TEM mode is proposed. In this DO configuration, a ridged circular waveguide is used to replace the cylindrical waveguide to decrease its radial dimension. The RF field of the operating π-mode is extracted from every resonator cavity and guided to the ridged circular waveguide. Even at the operating frequency of 1.55 GHz, the ridged circular waveguide can reduce the cutoff radius of the RF wave to 73 mm. The output RF field is further effectively converted to the TEM mode by a compact mode converter. Moreover, in the resonant system, a 10-cavity rising-sun slow wave structure (SWS) is applied to lower the phase velocity of the operating spatial harmonic and enhance the mode separation between the operating mode and the adjacent mode. The particle-in-cell (PIC) simulations demonstrate that the practical RM could output a relatively pure TEM mode at the frequency of 1.55 GHz, and its total efficiency is up to 60% with gigawatt radiation power for a diode voltage of 400 kV. [ABSTRACT FROM AUTHOR]

Published
2019
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39. Study on Weld Line Strength of Talc-filled ABS Compounds.

Author

DAI Jianjian, HE Chaoxiong, GUAN Huanxiang, and CHEN Pingxu

Abstract

The talc-filled ABS compounds were prepared by melt blending, and the effects of talc content and size as well as lubrication on their weld line strength were investigated. The micro-morphology of the interface between weld line and dispersed fillers was observed with scanning electron microscope. The results indicated that the weld line strength of the compoundsdecreased due to the barrier effect on diffusion and fusion of macromolecular chains by talc sheets. Theweld line strength of ABS could be improved effectively by incorporation of talc at a low content, mixture of talc and wollastonite, or amide lubrication with polar groups. The ABS compounds achieved the weld mark strength of 33. 4 MPa when 5 wt % of talc, 5 wt % of wollastonite and 1 wt %of modified amide lubrication were added. [ABSTRACT FROM AUTHOR]

Published
2018
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40. Rapid measurement of the net charge on nanoparticles in optical levitation system

Author

Wang, Jinchuan, Li, Cuihong, Zhu, Shaochong, He, Chaoxiong, Fu, Zhenhai, Zhu, Xunmin, Chen, Zhiming, and Hu, Huizhu

Abstract

Accurate measurement of the net charge on nanoparticles is critical in research and practical applications. We proposed a method for accurately measuring charge through thermally and harmonically driven motion signals. Our direct-charge-calculation method achieves accuracies of better than 5% at thermal equilibrium pressures of more than 10 mbar and approximately 20% for pressures as low as 3 mbar. This method can improve the measurement accuracy for mass and density through iterations and provide a direction for non-contact characterization of atmosphere and space dust.

Published
2023
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