Interplanetary coronal mass ejections (ICMEs) are major drivers of heliospheric disturbances and space-weather effects. Here we present a multi-spacecraft study of 96 magnetic clouds (MCs) distributed over a broad range of heliocentric distances, and reconstruct their internal magnetic structure with a uniform-twist Gold–Hoyle (GH) flux-rope model. From the fits, we derive the axial field strength B_0, the twist density (turn density) τ, the GH parameter ω, and the integrated twist number n. We find that B_0 and the turn density τ both decrease with increasing heliocentric distance, consistent with expansion and axial stretching during propagation. A key result is that the upper envelope in the τ–R plane corresponds to a nearly constant boundary in the dimensionless GH parameter ω=2πRτ, close to ω∼2. Therefore, the inferred upper value of τ is not scale-independent, but follows τ_max≃ ω_max/(2πR) for a given flux-rope radius. In contrast, the estimated integrated turn number n shows no similarly clear radial organization in the present sample. This study investigates the ICME structure and magnetic field characteristics across heliocentric distances from 0.07 to 5.4 AU, thereby providing observational constraints on the large-scale evolution of interplanetary magnetic flux ropes.

Interplanetary coronal mass ejections (ICMEs) are major drivers of heliospheric disturbances and space-weather effects. Here, we present a multispacecraft study of 96 magnetic clouds (MCs) distributed over a broad range of heliocentric distances and reconstruct their internal magnetic structure with a uniform-twist Gold–Hoyle (GH) flux-rope model. From the fits, we derive the axial field strength B _0 , the twist density (turn density) τ , the GH parameter ω , and the integrated twist number n . We find that B _0 and the turn density τ both decrease with increasing heliocentric distance, consistent with expansion and axial stretching during propagation. A key result is that the upper envelope in the τ – R plane corresponds to a nearly constant boundary in the dimensionless GH parameter ω = 2 πRτ , close to ω ∼ 2. Therefore, the inferred upper value of τ is not scale independent but follows ${\tau }_{\max }\simeq {\omega }_{\max }/(2\pi R)$ for a given flux-rope radius. In contrast, the estimated integrated turn number n shows no similarly clear radial organization in the present sample. This study investigates the ICME structure and magnetic field characteristics across heliocentric distances from 0.07 to 5.4 au, thereby providing observational constraints on the large-scale evolution of interplanetary magnetic flux ropes.

Interplanetary scintillation (IPS) tomography is a key technique for probing the three-dimensional structures of the inner heliosphere and for space weather forecasting. In this paper, we quantify how the performance of an IPS-driven magnetohydrodynamic computer-assisted tomography model depends on the coverage of the input IPS observations. Using the ISEE IPS data during Carrington rotation 2075 in 2008 as the sole IPS constraint, we reconstruct the density and speed of the ambient solar wind. Comparison with OMNI in situ data at 1 au shows that three corotating interaction regions (CIRs I–III) are reasonably reproduced. While the CIRs II and III agree well with observations, CIR I arrives nearly 4 days earlier and exhibits a much stronger density compression than measured. Tracing the 3D CIR structures back toward the Sun reveals that the discrepancy arises from sparse IPS data coverage over the southern hemisphere. The lack of IPS observational constraints for the source region of the CIR I causes the southern fast solar wind to artificially protrude into the heliospheric equator, producing an overly wide and strong CIR. Our results indicate the critical role of observation coverage in IPS tomography and highlight the benefits of coordinated IPS observations within the Worldwide IPS Stations (WIPSS) network.

Context. Previous studies have shown that a streamer blob might originate in the lower corona and thus be affected by activity in that region. While the base of one streamer might differ from that of another, it can be cataloged into two distinct types: active region streamers (ARSs) that have active regions at their base, and quiet equatorial streamers (QESs) that do not have an active region underneath. The difference between the blob properties in ARSs and those in QESs remains unknown. Aims. We compare the properties of propagating blobs in ARSs and QESs. Methods. By analyzing the whole-year observations from SOHO/LASCO/C2 in 2018, we carried out a statistical analysis of the properties of propagating blobs in ARSs and QESs. Results. We found that the properties of streamer blobs are very different from one blob to another. The occurrence rate of blobs in ARSs is about twice as high as that in QESs. On average, the ARS blobs have significantly higher initial velocities and slightly higher accelerations, but slightly lower heights of first appearance than the QES blobs. There is a weak positive correlation between the initial velocities and heights of first appearance in the two groups of streamer blobs. The correlation between the accelerations and heights of first appearance in ARS blobs is negative, while that in QES blobs is positive. Conclusions. Our results provide statistical evidence that a higher degree of activity at the coronal base of a streamer can cause more dynamic blobs higher up, and that it affects the structures of the solar wind originating in the region.

Interplanetary scintillation (IPS) phenomenon behaves as twinkling of a compact radio source due to scattering in the solar wind. Here we report the first identification of IPS signal by a new parabolic dish antenna with its diameter of 30 m, observed on 2024 March 1. The radio source of 3C446 at solar elongation of 6.4° was targeted during its 5 minute transit across our antenna beam at ArQi (115.13°E, 44.73°N). Our receiver is characterized as simultaneous measurements of dual polarizations from 3C446 emission, integrated over a 40 MHz bandwidth around its central frequency of 1.4 GHz. The horizontally and vertically polarized components, though independently and simultaneously measured, show a strong correlation in terms of both time-series and power spectral analyses. Using a spectra-fitting method on basis of the classic IPS theory, the solar wind speed in our observation case is inferred to be 283 km s ^−1 . Such a solar wind speed inferred at the piercing point of 24 solar radii along our IPS ray-path reaffirms the interplanetary diagnostic capability of ground-based IPS technique. Our first-light IPS observation at ArQi represents a significant advance in the ongoing commissioning phase of our IPS-dedicated telescope facility within the Chinese Meridian Project–Phase II.

Solar flares, coronal mass ejections (CMEs) and enegertic particles, etc., are the driving sources that may cause catastrophic space weathers. It is desirable to obtain information of solar eruptions like flares and CMEs, etc., propagating from the Sun to the near-Earth space. The Chinese Meridian Project includes the interplanetary scintillation (IPS) telescopes to investigate the structures and properties of the solar wind throughout the inner heliosphere. From IPS observations one can obtain disturbance information on CME speeds and thus on CME arrival times well off the Sun-Earth line. When combined with modeling techniques and/or in situ data, other parameters such as CME masses can also be obtained, along with CME propagation directions and arrival times. Therefore, a radio telescope array with three 140 m 40 m parabolic cylinder antennas at the main site and two 30 m antennas at two subsites about 200 km away from each other, featuring a multi-site array with the highest sensitivity dedicated to IPS observations in the world, has been supported as a major facility of the Chinese Meridian Project. The detailed description of the final optimized design and implementation of this IPS radio telescope array is introduced. The antennas and array configuration, the analog and digital receiving systems for the main site and subsites, the calibration of the IPS telescope array and data processing are described. Finally the overall performance of the IPS telescope array is provided. The detailed information on the IPS radio telescope array will facilitate the use of its data serving space weather research and applications.

The solar wind is a high-speed stream of charged particles originating from the solar corona and continuously radiating outward. Investigating the formation mechanisms of the solar wind and its propagation and impact in interplanetary space provides crucial support for both space science research and space engineering. The newly constructed Interplanetary Scintillation Telescope under the Meridian Project II aims to monitor the propagation of background solar wind and solar storm disturbances in interplanetary space. This telescope system adopts an observation mode of one main station and two sub stations, with the sub stations equipped with two 30-meter parabolic telescopes. This paper primarily focuses on the development and performance of the 30-meter telescope.

Remote brightening (RB) is compact brightening at footpoints of magnetic loops, which are remotely connecting to and confining an eruption in the solar atmosphere. Here, we report on observations of an RB resulting from an EUV jet with a speed of about 90 km s-1. The loops connecting the RB and the jet have an apparent length of about 59 Mm. Intriguingly, the RB exhibits at least two episodes of brightenings, as characterized by two peaks in its lightcurve. The energies that sustain the first and second peaks of the RB are 6.3 x 1026 erg and 8.4 x 1026 erg, respectively, and comprise a significant proportion of the total energy. The first peak of the RB brightenings coincides with the jet's peak with a time delay of 12 s, while the second peak lags behind by 108 s. Besides the flows of the ejecta, we have identified two additional flows originating from the eruption site. One is relatively cool with a temperature of log10(T/K)=5.8 -6.1 and a speed of about 275 +/- 15 km s-1. The other is hot with a temperature of log10(T/K)=7.0 -7.3 and a much greater speed of about 750 +/- 70 km s-1. We attribute the second peak of RB directly to this hot flow, which our numerical experiments suggest is the result of a slow shock wave. Considering the minimal time delay between the first peak of RB and the eruption, we infer that this first episode is due to heating by nonthermal electrons. Our research demonstrates that the dynamics in an RB can offer vital insights into the nature of the corresponding eruption and help understand how energy is distributed throughout the solar atmosphere.

Remote brightening (RB) is compact brightening at footpoints of magnetic loops, which are remotely-connecting to and confining an eruption in the solar atmosphere. Here, we report on observations of an RB resulting from an EUV jet with a speed of about 90 km s^-1. The loops connecting the RB and the jet have an apparent length of about 59 Mm. Intriguingly, the RB exhibits at least two episodes of brightenings, as characterised by two peaks in its lightcurve. The energies, which sustain the first and second peaks of the RB, are 6.3×10^26 erg and 8.4×10^26 erg, respectively, and take a significant proportion of the total energy. The first peak of the RB brightenings coincides with the jet's peak with a time delay of 12 seconds, while the second peak lags behind by 108 seconds. Besides the flows of the ejecta, we have identified two additional flows originating from the eruption site. One is relatively cool with a temperature of log_10T/K=5.8-6.1 and has a speed of about 275±15 km s^-1. The other is hot with a temperature of log_10T/K=7.0-7.3 and travels much faster with a speed of about 750± 70 km s^-1. We attribute the second peak of RB directly to this hot flow, which our numerical experiments suggest is the result of a slow shock wave. Considering the minimal time delay between the first peak of RB and the eruption, we infer this first episode is due to heating by nonthermal electrons. Our research demonstrates that the dynamics in an RB can offer vital insights into the nature of the corresponding eruption and help understand how the energy is distributed throughout the solar atmosphere.

Alfvén waves play a significant role in solar coronal heating, solar wind acceleration, and Alfvénic turbulence formation. As a fundamental process, magnetic reconnection has long been credited as a crucial source of Alfvén waves. However, how magnetic reconnection triggers Alfvén waves remains unclear. Here, employing high-resolution simulations of three-dimensional bursty interchange magnetic reconnection in the solar corona, we unveil that Alfvén waves are spontaneously excited in the reconnecting current sheet and propagate bidirectionally, mainly along unreconnected magnetic fields. Generated by the transient reconnection events, flux ropes with enhanced total pressure persistently displace the magnetic fields in their surrounding, launching the observed large-amplitude and quasi-linearly polarized Alfvén waves, which carry substantial energy for heating the quiet corona and accelerating the solar wind. Our findings underscore the natural association between Alfvén waves and intermittent magnetic reconnection, which can be generalized to various plasma systems in astrophysical and laboratorial environments.

As the first comprehensive report on China's newly operational interplanetary scintillation (IPS) telescope, this paper elaborates the world's most sensitive instrument for tracking solar wind disturbances across interplanetary space, which comprises three 140 m × 40 m parabolic cylindrical antennas, achieving high sensitivity (∼8 mJy) and resolutions of 0.46° at 327 MHz and 0.23° at 654 MHz, as well as a wide field of view enabled by a hybrid design of east‐west mechanical scanning (±45°) and north‐south electronic scanning (±60°). It is the first IPS‐dedicated telescope using a dual‐band and dual‐polarized multi‐beam phased array feed (PAF) receiver with a hybrid beamforming architecture. A diffusion model‐based generative calibration method termed phased array alignment diffusion algorithm (PANDA) is first proposed, which addresses the challenges of maintaining channel consistency posed by non‐Gaussian perturbations in large‐scale phased array systems. This approach leverages a data‐driven Bayesian inference method to precisely extrapolate the calibration weights as near to signal‐to‐noise ratio (SNR) upper bound as possible from sparse and noisy acquisition, ensuring channel consistency across the huge array. Experimental results demonstrate that PANDA effectively mitigates array perturbations and makes fewer measurements more informative (attaining 94.2% of the SNR upper bound with only 8.85% measurements), thereby establishing a unified calibration paradigm that enables high‐sensitivity observations with the Meridian Project Phase II IPS telescope and other next‐generation large‐scale phased array telescopes.

The magnetic fields and dynamical processes in the solar polar regions play a crucial role in the solar magnetic cycle and in supplying mass and energy to the fast solar wind, ultimately being vital in controlling solar activities and driving space weather. Despite numerous efforts to explore these regions, to date no imaging observations of the Sun's poles have been achieved from vantage points out of the ecliptic plane, leaving their behavior and evolution poorly understood. This observation gap has left three top-level scientific questions unanswered: How does the solar dynamo work and drive the solar magnetic cycle? What drives the fast solar wind? How do space weather processes globally originate from the Sun and propagate throughout the solar system? The Solar Polarorbit Observatory(SPO) mission, a solar polar exploration spacecraft, is proposed to address these three unanswered scientific questions by imaging the Sun's poles from high heliolatitudes. In order to achieve its scientific goals, SPO will carry six remote-sensing and four in-situ instruments to measure the vector magnetic fields and Doppler velocity fields in the photosphere, to observe the Sun in the extreme ultraviolet, X-ray, and radio wavelengths, to image the corona and the heliosphere up to 45 Rs, and to perform in-situ detection of magnetic fields,and low-and high-energy particles in the solar wind. The SPO mission is capable of providing critical vector magnetic fields and Doppler velocities of the polar regions to advance our understanding of the origin of the solar magnetic cycle, providing unprecedented imaging observations of the solar poles alongside in-situ measurements of charged particles and magnetic fields from high heliolatitudes to unveil the mass and energy supply that drive the fast solar wind, and providing observational constraints for improving our ability to model and predict the three-dimensional(3D) structures and propagation of space weather events.

Nanoflares, which are consequences of braids in tangled magnetic fields, are an important candidate to heat the solar corona to a million degrees. However, their observational evidence is sparse, and many of their observational characteristics are yet to be discovered. With the high-resolution observations taken by the Extreme Ultraviolet Imager onboard the Solar Orbiter, here we study a series of ejections of plasma blobs resulting from braided magnetic loops in the upper transition region and reveal some critical characteristics of such processes. The cores of these ejections have a size of about 700 km, a duration of less than 1 minute, and a speed of about 90 km s ^−1 . An important characteristic is that these plasma blobs are apparently constrained by the postreconnection magnetic loops, along which they show an extension of up to about 2000 km. The propagation of unbraiding nodes along the main axis of the tangled loops has a speed of about 45 km s ^−1 . The separation angles between the postreconnection loops and the main axis of the tangled loops are about 30°. The observations from the Atmospheric Imaging Assembly reveal that the braiding loops are upper transition region structures. Based on these observations, the typical magnetic free energy producing a blob is estimated to be about 3.4 × 10 ^23 erg, well in the nanoflare regime, while the kinematic energy of a blob is about 2.3 × 10 ^23 erg, suggesting that a majority of magnetic free energy in a magnetic braid is likely transferred into kinematic energy.

The typical structure of a coronal mass ejection (CME) was identified as a three-part morphology, which includes a bright front, a dark cavity, and a bright core, with the cavity and the core generally regarded as flux rope and eruptive prominence. However, there are three-part CMEs that are not associated with prominences. In this work, we conduct a high-resolution simulation of the 2021 December 4 CME mimicked with a spheromak flux rope to investigate the formation of the three-part morphology in the solar corona. The CME, with no signatures of prominence at the beginning, evolves into a high–low–high-density structure, which appears in a coronagraph image as a bright front immediately followed by a dark cavity with a bright core behind. The moving and expanding spheromak flux rope sweeps up the solar wind plasma and meanwhile, the plasma at its utmost edge is compressed, which produces the high-density front overlying the flux rope. It is also found that the expansion of the flux rope is uneven, with strong expansion at its outlying area and weak expansion at its central and rear parts. The differential expansion rates lead to the distinct rarefaction rates of the plasma, which results in the formation of the low-density cavity and the high-density core within the flux rope. Our three-dimensional study for the first time demonstrates that the evolution of the flux rope can self-consistently generate the three-part density structure, which improves the understanding of CME’s morphologies in coronagraph images.

We investigate the wavevector and variance anisotropies in the inertial range of the young solar wind observed by the Parker Solar Probe (PSP). Using the first 19 encounters of PSP measurements, we identify the young solar wind from different source regions: coronal hole (CH) interiors, streamers, and low Mach-number boundary layers (LMBLs), i.e., the peripheral region inside CHs. We assess the wavevector anisotropy with the 2D and slab turbulence model for the CH wind and streamer wind and the nearly incompressible MHD turbulence model for the LMBL wind, where Taylor’s hypothesis becomes questionable. Unlike the ∼80% 2D contribution typically reported at 1 au, our results show that only 26% of the inertial range energy is associated with 2D fluctuations in the CH wind, and this fraction increases to 45% in the streamer wind. As a representation of the LMBL wind, similarly, the oblique sub-Alfvénic intervals and near-subsonic intervals are characterized by the dominance of slab fluctuations. All the results suggest that slab fluctuations are more abundant in the young solar wind below 0.3 au than at 1 au. Furthermore, we find a dependence of the variance anisotropy in the inertial range on proton plasma beta β _p . The variance anisotropy is the strongest in the LMBL wind with the lowest β _p and the weakest in the streamer wind with the highest β _p . This contrast can be interpreted as the remnant of fluctuations from the coronal sources.

Prominences are important features in the solar atmosphere. Their activities often develop into solar eruptions, such as flares and/or coronal mass ejections. We report here on observations of activities of two crossing prominences and the resulting oscillations observed with the Advanced Space-based Solar Observatory (ASO-S) and the Solar Dynamics Observatory. We observed the two crossing prominences rising simultaneously with a speed of about 100 km s−1. The lower-lying prominence consists of threads that show increase of writhe during the rising process. We find evidence that the writhe of the lower-lying prominence is transferred into the overlying one. This transfer of writhe leads to a failure of the eruption of the lower-lying prominence and a shearing motion of the legs of the overlying prominence. The failed eruption of the lower-lying prominence also triggers kink oscillations of its threads, which show periods of about 300 s and amplitudes of less than 10 Mm. Such oscillations are considered to be intrinsic mode and can help to probe the magnetic field of the prominence. Our observations support the idea that the transfer and release of writhe play an important role in confining eruptions of a prominence, and interactions among prominences/filaments might be a crucial aspect of a solar eruption.

The heat dissipation of three-dimensional (3D) integrated Micro-Electro-Mechanical Systems (MEMS) has garnered considerable attention in scientific research and electronic applications in recent years. As power demands increase, device sizes decrease, and energy consumption is limited, the use of liquid and forced air cooling techniques is diminishing. In light of the growing emphasis on achieving carbon neutrality, there is renewed interest in passive cooling methods, which present a new imperative for environmentally-friendly thermal management of chips in the field of green energy. While the concept of designing thermal paths to mitigate heat in chips is not novel, it has become increasingly important due to the rapid accumulation of heat, reduction in chip volume, and the need to minimize energy consumption and carbon emissions. Consequently, the implementation of appropriate cooling structures within the available space of the chips has emerged as an appealing approach to enhance passive cooling. In order to tackle this challenge, four cooling structures, namely embedding network structure, overlaying extension platform, overlaying micro-pillar array, and overlaying surface microstructures, have been employed in the packaging process to augment the passive cooling capabilities of the chips. In this study, a 3D packaging model is developed to analyze the thermal characteristics of MEMS under the influence of power, TSV voltage, and heat source area using the finite element method. Additionally, the cooling structures are optimized based on the cooling performance analysis, taking into account the self-remaining space within the system and the heat source area factor. The application of four different cooling structures in 3D MEMS leads to enhanced cooling performance. In the event that liquid cooling and forced air cooling are not utilized, the system experiences a decrease in maximum temperature by 3.66 K, resulting in a corresponding decrease in temperature difference by 43.79 %. These reductions significantly contribute to the mitigation of thermal deformation and stress in MEMS, thereby enhancing the thermal reliability of the system. To verify the accuracy of the thermal simulation, a thermal test is conducted on the embedded network structure under simulated conditions. The thermal simulation, which has been validated through thermal testing, indicates that the implementation of four cooling structures within the self-contained area of MEMS has a notable effect on reducing temperature. This finding holds promise for its potential application in 3D MEMS.