Solar Radio Bursts with Drifting Stripes in Emission and Absorption

This review covers fairly comprehensively experimental and theoretical research on the fine structure of types zebra pattern (ZP) and fiber bursts (FB) in solar type II + IV radio bursts. The basic attention is given to the latest experimental data. A comparative analysis of several recent solar type IV radio outbursts with these fine structure in dynamical radio spectra is carried out using available ground-based and satellite data (Yohkoh, SOHO, TRACE, RHESSI). New data on microwave zebra structures and fiber bursts testifies that they are analogous to similar structures observed at meter wavelengths. The discovery of the superfine structure, in the form of millisecond spikes is the most significant new effect in the cm range. All basic theoretical models of the zebra pattern and fiber bursts are discussed critically. Two main models are studied for their interpretation: (i) interactions between electrostatic plasma waves and whistlers, (ii) radio emission at double plasma resonance (DPR). The relative significance of several possible mechanisms remains uncertain.     

Observation of Transition Region Fine Structures with Soho/Sumer

We present a preliminary analysis of two quiet Sun transition region areas observed with the SOHO/SUMER spectrometer, using lines from oxygen, nitrogen and silicon. The average quiet Sun physical parameters are studied as a function of line intensity. Systematic variations of line position and width with increasing intensity are found. A large number of small-scale active points have been observed, and preliminary analysis of the physical properties and dynamics of these active features is presented. A jet-like structure, found in an active point, is also investigated and its velocity along the line of sight determined. This revised version was published online in June 2006 with corrections to the Cover Date.     

Radio Emissions from Solar Active Regions

Solar active region coronae are known for strong magnetic fields permeating tenuous plasma, which makes them an ideal astronomical laboratory for magnetohydrodynamics research. It is, however, relatively less known that this physical condition also permits a very efficient radiation mechanism, gyro-resonant emission, produced by hot electrons gyrating in the coronal magnetic field. As a resonant mechanism, gyro-emission produces high enough opacity to fully reveal the coronal temperature, and is concentrated at a few harmonics of the local gyrofrequency to serve as an excellent indicator of the magnetic field. In addition, the polarization of the ubiquitous free–free emission and a phenomenon of depolarization due to mode coupling extend the magnetic field diagnostic to a wide range of coronal heights. The ability to measure the coronal temperature and magnetic field without the complications that arise in other radiative inversion problems is a particular advantage for the active region radio emissions available only at these wavelengths. This article reviews the efforts to understand these radiative processes, and use them as diagnostic tools to address a number of critical issues involved with active regions.     

On the Differences in Composition between Solar Energetic Particles and Solar Wind

Although the average composition of solar energetic particles (SEPs) and the bulk solar wind are similar in a number of ways, there are key differences which imply that solar wind is not the principal seed population for SEPs accelerated by coronal mass ejection (CME) driven shocks. This paper reviews these composition differences and considers the composition of other possible seed populations, including coronal material, impulsive flare material, and interplanetary CME material.     

典型海上热发射动力学效应及影响因素分析

考虑海上发射环境特殊性,分析了发射船承受的典型海浪以及风环境,针对陆基发射时运载火箭直接坐落在发射台上的裸箭热发射方式,分析了该支撑形式在海上动态环境下的射前稳定性,获得海上裸箭热发射方式的承受晃动极限。为解决陆基热发射支撑方式不满足三级海况发射稳定性的问题,提出运载火箭的框架式扶稳措施,通过框架内的柔性支撑保证运载火箭的射前稳定性。构建由火箭、等效甲板、导向框架、导轨、柔性支撑、发射台等组成的发射系统动力学仿真模型,开展复杂海况条件下的发射动力学分析,获得了框架式热发射方式在典型海况条件下,不同因素对火箭出框过程飞行姿态、安全间隙等影响规律,可为运载火箭框架式热发射的海上动基座发射动力学安全性评估提供技术支撑,并用于框架式热发射方式的海上动基座环境适应性的综合评价。     

Flaring loop parameters estimated from solar decimeter type U-like and type J-like fine structures

This work presents the analysis of five fine structures in the solar radio emission, observed between June 2000 and October 2001 by the Brazilian Solar Spectroscope (BSS), in the decimeter frequency band of 950–2500 MHz. Based on their morphological characteristics identified in the dynamic spectra, the fine structures had been classified as type U-like or type J-like bursts. Such emissions are variants of the type III bursts. They support the hypothesis of generation by plasma emission mechanism, from interaction of electron beams accelerated during solar flares, propagating along closed magnetic structures, within the trapped plasma of the solar corona. The spectral and temporal characteristics of the five fine structures had been obtained from the dynamic spectra and the parameters of the agent and the emitting source have been determined, assuming both fundamental and harmonic emissions. The analysis revealed the flux density of the structures is less than 20–80 s.f.u. For assumption of harmonic emission, the interval of values for the source parameters estimated are: the loop size is (0.3–5.1) × 10¹⁰ cm; the electron beam velocity is in the range of 0.16–0.53 c; the temperature of coronal loop top is of the order of (0.25–1.55) × 10⁷ K; and the low limit for the magnetic field is of 7–26 G. These results are in agreement with previous determinations reported in the literature.     

Ground-based and satellite DC-ULF electric field anomalies around Wenchuan M8.0 earthquake

The ground-based and satellite DC-ULF electric field data were analyzed around Wenchuan M8.0 earthquake on May 12, 2008 in China. The results show that ground electric field anomalies occurred at 3 stations located to the north and south of the epicenter with the amplitude of 3–100 mV/km. The change shapes and their amplitude of ground electric field anomalies are different largely due to their individual underground layer conductivity, water level and so on. The analysis of long time series illustrates that the abnormal geoelectric field started since March 2008. Onboard the DEMETER satellite, the ULF waveforms of electric field were collected and processed by wavelet transform method. The disturbances in the ionosphere were about 3–5 mV/m at a frequency band lower than 0.5 Hz. When the ground and space electric field anomalies were compared, their occurrence time and spatial distribution points are consistent with each other, including the long time anomalies from March 2008 and the short term ones 1–2 days before the Wenchuan earthquake. Finally, the coupling mechanism was discussed.     

Two successive partial mini-filament confined ejections

Active region (AR) NOAA 11476 produced a series of confined plasma ejections, mostly accompanied by flares of X-ray class M, from 08 to 10 May 2012. The structure and evolution of the confined ejections resemble that of EUV surges; however, their origin is associated to the destabilization and eruption of a mini-filament, which lay along the photospheric inversion line (PIL) of a large rotating bipole. Our analysis indicate that the bipole rotation and flux cancellation along the PIL have a main role in destabilizing the structure and triggering the ejections. The observed bipole emerged within the main following AR polarity. Previous studies have analyzed and discussed in detail two events of this series in which the mini-filament erupted as a whole, one at 12:23 UT on 09 May and the other at 04:18 UT on 10 May. In this article we present the observations of the confined eruption and M4.1 flare on 09 May 2012 at 21:01 UT (SOL2012-05-09T21:01:00) and the previous activity in which the mini-filament was involved. For the analysis we use data in multiple wavelengths (UV, EUV, X-rays, and magnetograms) from space instruments. In this particular case, the mini-filament is seen to erupt in two different sections. The northern section erupted accompanied by a C1.6 flare and the southern section did it in association with the M4.1 flare. The global structure and direction of both confined ejections and the location of a far flare kernel, to where the plasma is seen to flow, suggest that both ejections and flares follow a similar underlying mechanism.     

硅基底上外延生长过渡金属硅化物薄膜的研究

过渡金属与硅的接触系统一直被人们所关注,是因为它们在界面处具有肖特基势垒的形成、过渡金属硅化物的外延生长、制作器件的稳定和耐高温等重要性.因此在硅基底上形成金属硅化物薄膜也被广泛应用于半导体工业.对硅衬底上蒸发的Cr、Fe、Mn薄膜进行热处理,通过固相反应法(SPR)制备过渡金属硅化物薄膜,即经过对过渡金属硅化物(薄膜)/Si系统进行各种温度、不同时间的热处理,制备出各种过渡金属硅化物薄膜.对于制成的各种硅化物薄膜,用X射线衍射法(XRD)和软X射线发射分光光谱法(SXES)对它们的组成成分进行了分析和确认.并且,由这两种分析方法表明:各种过渡金属硅化物薄膜在硅衬底上各形成了单一相的均匀层硅化物薄膜.     

加筋板中超高速撞击声发射源定位方法

加筋板是航天器上的常用结构。为研制基于声发射技术的在轨感知系统,需要研究加筋板中声发射波传播规律及撞击源定位方法。文章测定了断铅信号在加筋板中的传播速度,对沿不同方向传播的波速进行了比较;通过有限元仿真,研究了筋体几何尺寸对板中声发射信号传播规律的影响。试验与仿真的结果表明:筋体对信号压缩波波速影响较小,但会造成信号第一幅值的衰减,在传感器布局设计时需要考虑到该因素。将加筋板中声发射信号传播速度取为沿不同方向传播波速的平均值,可将源定位问题转化成求取函数最小值的优化问题,在加筋板上对断铅波源和超高速撞击波源进行定位效果较好。