Search

Your search keyword '"Wei, Y. Y."' showing total 324 results
Start Over Author "Wei, Y. Y."
324 results on '"Wei, Y. Y."'

1. Anisotropy of Magnetic Field Spectra at Kinetic Scales of Solar Wind Turbulence as Revealed by Parker Solar Probe in the Inner Heliosphere

Author

Huang, S. Y., Xu, S. B., Zhang, J., Sahraoui, F., Andres, N., He, J. S., Yuan, Z. G., Deng, X. H., Jiang, K., Wei, Y. Y., Xiong, Q. Y., Wang, Z., Yu, L., and Lin, R. T.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Physics - Plasma Physics, Physics - Space Physics
Abstract

Using the Parker Solar Probe data taken in the inner heliosphere, we investigate the power and spatial anisotropy of magnetic-field spectra at kinetic scales (i.e., around sub-ion scales) in solar wind turbulence in the inner heliosphere. We find that strong anisotropy of magnetic spectra occurs at kinetic scales with the strongest power in the perpendicular direction with respect to the local magnetic field (forming an angle theta_B with the mean flow velocity). The spectral index of magnetic spectra varies from -3.2 to -5.8 when the angle theta_B changes from 90 to 180 (or 0) deg, indicating that strong anisotropy of the spectral indices occurs at kinetic scales in the solar wind turbulence. Using a diagnosis based on the magnetic helicity, we show that the anisotropy of the spectral indices can be explained by the nature of the plasma modes that carry the cascade at kinetic scales. We discuss our findings in light of existing theories and current development in the field., Comment: 15 pages, 3 figures, accepted by ApJL

Published
2022
Full Text
View/download PDF

2. In Situ Detection of Kinetic-Size Magnetic Holes in the Martian Magnetosheath

Author

Huang, S. Y., Lin, R. T., Yuan, Z. G., Jiang, K., Wei, Y. Y., Xu, S. B., Zhang, J., Zhang, Z. H., Xiong, Q. Y., and Yu, L.

Subjects
Physics - Space Physics, Astrophysics - Earth and Planetary Astrophysics, Physics - Plasma Physics
Abstract

Depression in magnetic field strength with a scale below one proton gyroradius is referred to as kinetic-size magnetic hole (KSMH). KSMHs are frequently observed near terrestrial space environments and are thought to play an important role in electron energization and energy dissipation in space plasmas. Recently, KSMHs have been evidenced in the Venusian magnetosheath. However, observations of KSMHs in other planetary environments are still lacking. In this study, we present the in situ detection of KSMHs in Martian magnetosheath using Mars Atmosphere and Volatile EvolutioN (MAVEN) for the first time. The distribution of KSMHs is asymmetry in the southern northern hemisphere and no obvious asymmetry in the dawn dusk hemisphere. The observed KSMHs are accompanied by increases in the electron fluxes in the perpendicular direction, indicating the cues of trapped electrons and the formation of electron vortices inside KSMHs. These features are similar to the observations in the terrestrail magtosheath and magnetotail plasma sheet and the Venusian magnetosheath. This implies that KSMHs are a universal magnetic structure in space., Comment: 16 pages, 4 figures, accepted by ApJ

Published
2021
Full Text
View/download PDF

3. Observational Evidence of Magnetic Reconnection in the Terrestrial Foreshock Region

Author

Jiang, K., Huang, S. Y., Fu, H. S., Yuan, Z. G., Deng, X. H., Wang, Z., Guo, Z. Z., Xu, S. B., Wei, Y. Y., Zhang, J., Zhang, Z. H., Xiong, Q. Y., and Yu, L.

Subjects
Physics - Plasma Physics, Astrophysics - Earth and Planetary Astrophysics, Physics - Space Physics
Abstract

Electron heating/acceleration in the foreshock, by which electrons may be energized beyond thermal energies prior to encountering the bow shock, is very important for the bow shock dynamics. And then these electrons would be more easily injected into a process like diffusive shock acceleration. Many mechanisms have been proposed to explain electrons heating/acceleration in the foreshock. Magnetic reconnection is one possible candidate. Taking advantage of the Magnetospheric Multiscale mission, we present two magnetic reconnection events in the dawn-side and dusk-side ion foreshock region, respectively. Super-Alfv\'enic electron outflow, demagnetization of the electrons and the ions, and crescent electron distributions in the plane perpendicular to the magnetic field are observed in the sub-ion-scale current sheets. Moreover, strong energy conversion from the fields to the plasmas and significant electron temperature enhancement are observed. Our observations provide direct evidence that magnetic reconnection could occur in the foreshock region and heat/accelerate the electrons therein., Comment: 17 pages, 4 figures, accepted by ApJ

Published
2021
Full Text
View/download PDF

5. The Ion Transition Range of Solar Wind Turbulence in the Inner Heliosphere: Parker Solar Probe Observations

Author

Huang, S. Y., Sahraoui, F., Andrés, N., Hadid, L. Z., Yuan, Z. G., He, J. S., Zhao, J. S., Galtier, S., Zhang, J., Deng, X. H., Jiang, K., Yu, L., Xu, S. B., Xiong, Q. Y., Wei, Y. Y., de Wit, T. Dudok, Bale, S. D., and Kasper, J. C.

Subjects
Physics - Space Physics, Astrophysics - Solar and Stellar Astrophysics
Abstract

The scaling of the turbulent spectra provides a key measurement that allows to discriminate between different theoretical predictions of turbulence. In the solar wind, this has driven a large number of studies dedicated to this issue using in-situ data from various orbiting spacecraft. While a semblance of consensus exists regarding the scaling in the MHD and dispersive ranges, the precise scaling in the transition range and the actual physical mechanisms that control it remain open questions. Using the high-resolution data in the inner heliosphere from Parker Solar Probe (PSP) mission, we find that the sub-ion scales (i.e., at the frequency f ~ [2, 9] Hz) follow a power-law spectrum f^a with a spectral index a varying between -3 and -5.7. Our results also show that there is a trend toward and anti-correlation between the spectral slopes and the power amplitudes at the MHD scales, in agreement with previous studies: the higher the power amplitude the steeper the spectrum at sub-ion scales. A similar trend toward an anti-correlation between steep spectra and increasing normalized cross helicity is found, in agreement with previous theoretical predictions about the imbalanced solar wind. We discuss the ubiquitous nature of the ion transition range in solar wind turbulence in the inner heliosphere., Comment: Accepted by ApJL

Published
2021
Full Text
View/download PDF

7. Characteristics of Magnetic Holes in the Solar Wind Revealed by Parker Solar Probe

Author

Yu, L., Huang, S. Y., Yuan, Z. G., Jiang, K., Xiong, Q. Y., Xu, S. B., Wei, Y. Y., Zhang, J., and Zhang, Z. H.

Subjects
Physics - Space Physics, Astrophysics - Solar and Stellar Astrophysics, Physics - Plasma Physics
Abstract

We present a statistical analysis for the characteristics and radial evolution of linear magnetic holes (LMHs) in the solar wind from 0.166 to 0.82 AU using Parker Solar Probe observations of the first two orbits. It is found that the LMHs mainly have a duration less than 25 s and the depth is in the range from 0.25 to 0.7. The durations slightly increase and the depths become slightly deeper with the increasing heliocentric distance. Both the plasma temperature and the density for about 50% of all events inside the holes are higher than the ones surrounding the holes. The average occurrence rate is 8.7 events/day, much higher than that of the previous observations. The occurrence rate of the LMHs has no clear variation with the heliocentric distance (only a slight decreasing trend with the increasing heliocentric distance), and has several enhancements around ~0.525 AU and ~0.775 AU, implying that there may be new locally generated LMHs. All events are segmented into three parts (i.e., 0.27, 0.49 and 0.71 AU) to investigate the geometry evolution of the linear magnetic holes. The results show that the geometry of LMHs are prolonged both across and along the magnetic field direction from the Sun to the Earth, while the scales across the field extend a little faster than along the field. The present study could help us to understand the evolution and formation mechanism of the LMHs in the solar wind., Comment: Accepted by ApJ

Published
2020
Full Text
View/download PDF

8. Kinetic Scale Slow Solar Wind Turbulence in the Inner Heliosphere: Co-existence of Kinetic Alfv\'en Waves and Alfv\'en Ion Cyclotron Waves

Author

Huang, S. Y., Zhang, J., Sahraoui, F., He, J. S., Yuan, Z. G., Andrés, N., Hadid, L. Z., Deng, X. H., Jiang, K., Yu, L., Xiong, Q. Y., Wei, Y. Y., Xu, S. B., Bale, S. D., and Kasper, J. C.

Subjects
Physics - Space Physics, Physics - Plasma Physics
Abstract

The nature of the plasma wave modes around the ion kinetic scales in highly Alfv\'enic slow solar wind turbulence is investigated using data from the NASA's Parker Solar Probe taken in the inner heliosphere, at 0.18 Astronomical Unit (AU) from the sun. The joint distribution of the normalized reduced magnetic helicity ${\sigma}_m ({\theta}_{RB}, {\tau})$ is obtained, where ${\theta}_{RB}$ is the angle between the local mean magnetic field and the radial direction and ${\tau}$ is the temporal scale. Two populations around ion scales are identified: the first population has ${\sigma}_m ({\theta}_{RB}, {\tau}) < 0$ for frequencies (in the spacecraft frame) ranging from 2.1 to 26 Hz for $60^{\circ} < {\theta}_{RB} < 130^{\circ}$, corresponding to kinetic Alfv\'en waves (KAWs), and the second population has ${\sigma}_m ({\theta}_{RB}, {\tau}) > 0$ in the frequency range [1.4, 4.9] Hz for ${\theta}_{RB} > 150^{\circ}$, corresponding to Alfv\'en ion Cyclotron Waves (ACWs). This demonstrates for the first time the co-existence of KAWs and ACWs in the slow solar wind in the inner heliosphere, which contrasts with previous observations in the slow solar wind at 1 AU. This discrepancy between 0.18 and 1 AU could be explained, either by i) a dissipation of ACWs via cyclotron resonance during their outward journey, or by ii) the high Alfv\'enicity of the slow solar wind at 0.18 AU that may be favorable for the excitation of ACWs.

Published
2020
Full Text
View/download PDF

9. Study on a High-Power W -Band Extended Interaction Klystron With Efficiency Toward 44%

Author

Zhang, Z., Cai, J. C., Yin, P. C., Su, Z. X., Zhang, X. K., Zhang, C., Zeng, L., Xu, J., Yue, L. N., Yin, H. R., Xu, Y., Zhao, G. Q., Wang, W. X., and Wei, Y. Y.

Abstract

In order to overcome the low efficiency (usually less than 25%) of millimeter-wave and terahertz (MMW/THz) klystrons, an exploratory study is conducted to improve the efficiency in the design of W-band extended interaction klystrons (EIKs). In this article, fast large-signal simulations using KlyC code are comprehensively used for the first time to accurately conduct full-scale parameterization of EIK, it is found that the upper limit of terahertz klystron efficiency is no longer solely dominated via the beam perveance, but rather restricted by various factors, including effective impedance, ohmic loss, cavity arrangement, and so on. The physical mechanism involved is so complex that the preliminary parametric sortation is mandatory to achieve very high efficiency (HE). Particle-in-cell (PIC) simulation results verified our theoretical evaluations, demonstrating that the W-band EIK proposed and optimized in this article could deliver up to 44.5% electronic efficiency and 39.2% RF efficiency around 100 GHz, with operating beam voltage of 50 kV and beam current of 2 A. The output power and saturation gain could achieve 39.2 kW and 65.5 dB, respectively, in which no instability is observed. In addition, a novel beam optics system (BOS) based on hybrid permanent magnets is proposed. Such compact BOS is exclusively developed to deal with the challenge induced by severe radial beam expansion in this EIK, which is the side-effect of the high intensity of beam-wave interactions. This study on high-power (HP) HE compact W-band EIK reveals the true potential of such types of devices in the MMW/THz regime.

Published
2025
Full Text
View/download PDF

10. Accurate Space Charge Modeling for 1-D Large Signal Simulation of Sheet Beam TWTs

Author

Zhang, X. K., Cai, J. C., Yin, P. C., Su, Z. X., Li, Z. X., Zhang, C., Zeng, L., Zhang, Z., Xu, J., Yue, L. N., Yin, H. R., Xu, Y., Zhao, G. Q., Xiang, W. W., and Wei, Y. Y.

Abstract

An improved space charge model for a 1-D large-signal simulation algorithm for sheet beam (SB) traveling wave tube (TWT) is proposed in this article, which is finally integrated into the simulation software KlyC. Rather than assuming a smooth rectangular waveguide for drifting tunnel as a conventional approach, the periodical geometric modification of metallic wall accounted for better modeling accuracy. The effect of the complex space charge field of modulated electrons in the slow wave structure (SWS) is approximated by modifying Green functions from the smooth waveguide system. To evaluate such modification coefficient, electrostatic problems are to be solved to calculate a series of Green functions of the space charge field within one period of SWS, before comparing with the Green function obtained from smooth rectangular boundaries. For most SB TWTs, the quasi-2-D SWS is employed, of which the modification coefficient could be calculated by 2-D numerical algorithms proposed in this article, aiming to speed up the evaluation. The 1-D large-signal simulation results conducted by KlyC with the improved space charge model are in good agreement with the CST particle-in-cell (PIC) simulations, where overall accuracy reaches several percent, with much faster computational speed (at least two orders of magnitude). Moreover, the proposed method of accurate space charge modeling can be further applied to any TWT with 3-D SWS theoretically.

Published
2024
Full Text
View/download PDF

11. Electron Pitch Angle Distributions in Magnetotail Tailward Flows.

Author

Wei, Y. Y., Huang, S. Y., Jiang, K., Yuan, Z. G., Xu, S. B., Zhang, J., Xiong, Q. Y., Wang, Z., Lin, R. T., and Yu, L.

Subjects
PLASMA flow, EARTHFLOWS, FLOW velocity, ELECTRON plasma, ELECTRONS
Abstract

Electron pitch angle distributions (PADs) are crucial to revealing electron acceleration and heating in geospace. The electron PADs in the Earth's magnetotail have been widely studied by statistical or case analysis. However, the statistical features of electron PADs in tailward flows are still unclear. We survey data from the Magnetospheric Multiscale (MMS) satellite to statistically investigate electron PADs in tailward flows in the Earth's magnetotail for the first time. We find that for most (66.3%) tailward flows, electrons with energy from 0.1 to 30 keV are mainly field‐aligned. The PADs of suprathermal (>2 keV) electrons in a part of tailward flows (26.3%) are mostly isotropic. Additionally, the perpendicular‐dominated PADs of suprathermal electrons only exist in a few (7.4%) tailward flows. According to the different dominant PADs of suprathermal electrons, the tailward flows are classified into three types: field‐aligned‐dominated type, isotropic‐dominated type and perpendicular‐dominated type flows. The dependence of electron PADs on plasma environmental parameters is investigated in these three types of flows. For field‐aligned‐dominated type flows, the field‐aligned anisotropy decreases toward the central plasma sheet (CPS) and with the increase of the energy. In addition, it is found that the field‐aligned anisotropy in the field‐aligned‐dominated tailward flows reduces noticeably when the |Vix| exceeds 800 km/s. In isotropic‐dominated type flows, the field‐aligned anisotropy of electrons with energy ≥10 keV also shows a slight decreasing trend toward the CPS. For perpendicular‐dominated type flows, the perpendicular anisotropy exhibits two non‐monotonic processes, initially increasing and then decreasing with the increase of distance from the CPS; while becomes more evident for higher energy electrons. Our statistical results indicate that in tailward flows, electron anisotropy depends on the distance from the CPS, energy and plasma flow velocity. Tailward flows are associated with the transport of plasma toward the distant tail, and the statistical analysis of electron PADs in these flows can improve our understanding of the related electron dynamics in the magnetotail. Key Points: Statistically features of field‐aligned‐dominated, isotropic‐dominated and perpendicular‐dominated type tailward flows are revealedFor the field‐aligned‐dominated type flows, the field‐aligned anisotropy decreases toward the central plasma sheet and with the increase of the energyThe perpendicular pitch‐angle anisotropy in the perpendicular‐dominated type flows is more evident for higher energy electrons [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

12. A Study of an Ultracompact High-Efficiency CSM MBK Using Hybrid-Modes Resonant Cavities

Author

Zeng, L., Cai, J. C., Su, Z. X., Yin, P. C., Zhang, X. K., Zhang, C., Zhang, Z., Xu, J., Yin, H. R., Yue, L. N., Xu, Y., Zhao, G. Q., Wang, W. X., and Wei, Y. Y.

Abstract

The multibeam klystron (MBK) faces the challenge of miniaturization together with stringent requirements for high power and high efficiency (HE) in L-band and below frequency regimes. Inspired by the core stabilization method (CSM), this article proposes three types of hybrid-modes resonant cavities, which can operate simultaneously in two harmonic modes. The large-signal simulation and 3-D particle-in-cell (PIC) simulation results demonstrate that this novel CSM MBK equipped with two hybrid-modes resonant cavities, operating at both fundamental and second harmonics, could provide up to 11.5-MW output power with 65.9% electronic efficiency at a total circuit length of 592 mm. This L-band MBK is launched with six beamlets, of which the beam voltage is 110 kV and the total current is 168 A. Moreover, compared with the MBKs designed by the traditional approach with only fundamental cavities or the CSM approach with individual harmonic cavities, the new hybrid HE klystron proposal exhibits not only decent efficiency performance but also, more importantly, ultracompact dimensions, where the circuit length is significantly shortened by about 45% and 35%, respectively.

Published
2024
Full Text
View/download PDF

14. In Situ Observations of Magnetic Reconnection Caused by the Interactions of Two Dipolarization Fronts.

Author

Jiang, K., Huang, S. Y., Wei, Y. Y., Yuan, Z. G., Xiong, Q. Y., Xu, S. B., and Zhang, J.

Subjects
MAGNETIC reconnection, CURRENT sheets, MAGNETIC flux, MAGNETIC fields
Abstract

Using high‐resolution data from the Magnetospheric Multiscale mission, an electron‐only reconnection current sheet is found between two successive dipolarization fronts (DFs). The electron‐only reconnection occurs between the northward component of the magnetic field of the flux pileup region (FPR) of the first DF (DF1) and the southward component of the magnetic dip of the second DF (DF2). The faster DF2 compresses the FPR of DF1, which constitutes an anti‐parallel topology and reduces the thickness of the current sheet. Further analysis shows that the current sheet is unstable to the electron tearing instability, which may power the onset of the reconnection. Our results suggest that these two DFs may merge into one by the reconnection, which sheds light on the evolution of DFs during their earthward propagation. Plain Language Summary: Magnetic reconnection, releasing magnetic energy and energizing plasmas, are believed to be responsible for the explosive phenomena in space. Though reconnection has been investigated for decades, the onset of reconnection is elusive. Dipolarization fronts (DFs), important carriers in the transportation of mass, magnetic flux, and energy in the magnetotail, can be generated by reconnections and will integrate into the geomagnetic field at last. The generation of DFs and dynamics at DFs are thoroughly probed by simulations and observations. However, the evolution of DFs during their earthward propagation is rarely inspected. In this work, we present an observation of an electron‐only reconnection between two successive DFs. The latter DF compresses the former DF and reduces the thickness of the current sheet between them. Inside the reconnection current sheet, electron tearing instability is unstable, which may power the reconnection. By reconnection, these two DFs may merge. Our observations can improve our understanding of the evolution of DFs in the magnetotail. Key Points: An electron‐only reconnection current sheet is found between two dipolarization frontsThe current sheet is unstable to the electron tearing instabilityDF2 compresses DF1 and thins the current sheet, which may initiate electron tearing instability and trigger the reconnection [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

15. Observation of Interchange Reconnection on Mars

Author

Lin, R. T., primary, Huang, S. Y., additional, Yuan, Z. G., additional, Jiang, K., additional, Xu, S. B., additional, Wei, Y. Y., additional, Xiong, Q. Y., additional, Zhang, J., additional, Wang, Z., additional, and Yu, L., additional

Published
2023
Full Text
View/download PDF

19. A Novel Efficient Computational Method for the Electron Optics System in Multibeam Klystrons With Applications to Manufacturing Sensitivities

Author

Su, Z. X., Cai, J. C., Yin, P. C., Zhang, X. K., Xu, J., Yue, L. N., Yin, H. R., Xu, Y., Zhao, G. Q., Wang, W. X., and Wei, Y. Y.

Abstract

In a multibeam klystron (MBK) electron optics system (EOS), the beamlets are significantly offset from the global magnetic central axis, in which the transverse component of the magnetic field in the center of each beamlet causes deviation of the beamlet from its local propagation axis. Therefore, it is mandatory to manipulate the magnetic focusing system to mitigate such impact within an acceptable level. This article proposes a novel theoretical analysis method that can rapidly and accurately evaluate electron beam trajectories, significantly improving the computational efficiency by at least $1\sim 2$ orders of magnitude, compared with the conventional full 3-D simulation approach, thus greatly speeding up the design process of MBK. Furthermore, this method can also be applied to determine sensitivities to manufacturing errors in klystron EOS. These errors can significantly impact the electron beam’s transmission characteristics, making a thorough analysis and evaluation mandatory. The effectiveness of the proposed method is demonstrated via the optimization of a 16-beam S-band high-power high-efficiency MBK and manufacturing errors analysis of C-band high-power high-efficiency single beam klystron (SBK).

Published
2024
Full Text
View/download PDF

20. Exploratory Study on High-Efficiency High-Power $W$-Band Klystron Based on Kladistron Technology

Author

Cai, J. C., Su, Z. X., Peauger, F., Xu, J., Burt, G., Yue, L. N., Yin, H. R., Zhao, G. Q., Xiang, W. W., Wei, Y. Y., Cai, J. C., Su, Z. X., Peauger, F., Xu, J., Burt, G., Yue, L. N., Yin, H. R., Zhao, G. Q., Xiang, W. W., and Wei, Y. Y.

Abstract

To achieve tens of kilowatt (kW) output power, W-band klystron usually employs a large beam tunnel to accommodate high current. The deteriorated effective impedance of the cavity could be reenhanced by adopting extended interaction (EI) cavities. In this article, a new approach utilizing simple fundamental modes in cascaded single-gap cavities for W-band klystron is proposed and discussed. Although the effective impedance of each cavity is far lower than its EI klystron (EIK) counterpart, this disadvantage could be efficiently compensated by densely populating those single-gap cavities using the kladistron technology previously conceived for the C-or X-band high-efficiency (HE) klystrons. However, kladistron is rarely reported and normally regarded as less a promising HE bunching technique overwhelmed by the self-excitation issues caused by adjacent mode coupling. Fortunately, such instability could be naturally suppressed in a higher frequency regime, so further exploration of kladistron technology is intriguing. In this article, an exemplary 30-kW W-band klystron equipped with big circular beam tunnel is designed using the kladistron technology, which finally shows no instability issues in 3-D particle-in-cell (PIC) simulation. This novel device delivers up to 37% electronic efficiency and 24% RF efficiency, validating that the kladistron concept is well suited for this millimeter-wave amplifier, which indicates possible HE substitutes for existing EIK technology.

Published
2023

21. Kinetic-Scale Topological Structures Associated with Energy Dissipation in the Turbulent Reconnection Outflow

Author

Huang, S. Y., Zhang, J., Xiong, Q. Y., Yuan, Z. G., Jiang, K., Xu, S. B., Wei, Y. Y., Lin, R. T., Yu, L., Wang, Z., Huang, S. Y., Zhang, J., Xiong, Q. Y., Yuan, Z. G., Jiang, K., Xu, S. B., Wei, Y. Y., Lin, R. T., Yu, L., and Wang, Z.

Abstract

Assisted with Magnetospheric Multiscale (MMS) mission capturing unprecedented high-resolution data in the terrestrial magnetotail, we apply a local streamline-topology classification methodology to investigate the categorization of the magnetic-field topological structures at kinetic scales in the turbulent reconnection outflow. It is found that strong correlations between the straining and rotational part of the velocity gradient tensor as well as the magnetic-field gradient tensor. The strong energy dissipation prefers to occur at regions with high magnetic stress or current density, which is contributed mainly by O-type topologies. These results indicate that the kinetic structures with O-type topology play more import role in energy dissipation in turbulent reconnection outflow., Comment: 19 pages, 4 figures, accepted by ApJ

Published
2023

28. Threshold Prediction of Spurious Oscillations in Klystrons Due to Backstreaming Electrons From Collector

Author

Su, Z. X., Cai, J. C., Yin, P. C., Li, W., Zhang, X. K., Zhang, C., Zeng, L., Xu, J., Yue, L. N., Yin, H. R., Xu, Y., Zhao, G. Q., Xiang, W. W., and Wei, Y. Y.

Abstract

In klystron amplifiers, spurious oscillations caused by the backstreaming electrons from collector may lead to unacceptable instabilities in experiments. To facilitate the fast and accurate analysis of such types of self-oscillations, rather than performing time-consuming particle-in-cell (PIC) simulations, the small signal theory to predict threshold conditions of spurious oscillations in klystrons has been further developed and implemented into the klystron computer code KlyC. If spurious oscillation occurs, the frequency and Q of the oscillation mode in a small signal regime can also be predicted. The effectiveness of the proposed threshold prediction method has been demonstrated through benchmarking against PIC codes, showing great agreement with result discrepancies at the several percentage level, while numerical computation time for small signal models is significantly (at least three orders of magnitude) faster than executed in the PIC simulations.

Published
2024
Full Text
View/download PDF

34. Sheet Electron Optical System for a 1.03-THz Traveling-Wave Tube

Author

Yin, P. C., primary, Xu, J., additional, Yang, R. C., additional, Luo, J. J., additional, Zhang, J., additional, Jia, D. D., additional, Fan, W. Y., additional, Ouyang, Y., additional, Yue, L. N., additional, Cai, J. C., additional, Yin, H. R., additional, Zhao, G. Q., additional, Guo, G., additional, Xu, L., additional, Wang, W. X., additional, Liu, W. X., additional, and Wei, Y. Y., additional

Published
2022
Full Text
View/download PDF

37. Kinetic‐Size Magnetic Holes in the Terrestrial Foreshock Region

Author

Huang, S. Y., primary, Wei, Y. Y., additional, Zhao, J. S., additional, Yuan, Z. G., additional, Deng, X. H., additional, Jiang, K., additional, Xu, S. B., additional, Zhang, J., additional, Xiong, Q. Y., additional, Zhang, Z. H., additional, Yu, L., additional, and Lin, R. T., additional

Published
2022
Full Text
View/download PDF

38. Anisotropy of Magnetic Field Spectra at Kinetic Scales of Solar Wind Turbulence as Revealed by the Parker Solar Probe in the Inner Heliosphere

Author

Huang, S. Y., primary, Xu, S. B., additional, Zhang, J., additional, Sahraoui, F., additional, Andrés, N., additional, He, J. S., additional, Yuan, Z. G., additional, Deng, X. H., additional, Jiang, K., additional, Wei, Y. Y., additional, Xiong, Q. Y., additional, Wang, Z., additional, Yu, L., additional, and Lin, R. T., additional

Published
2022
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results