电子束驱动的回旋激射不稳定性

对弱相对论性电子束驱动的回旋激射(maser)不稳定性的一般理论作了详细讨论.对在获得增长率实用表达式过程中若干解析表达式的推导与细节做了仔细的补充讨论和说明，还增加了增长率的近似表达式，并由此得到了回旋激射不稳定性主要特征的解析分析以及与精确计算的比较，使整个理论有一个完整的描述.侧重解析讨论，也提供了部分一般性的数值计算结果. 关键词： 回旋激射不稳定性 弱相对论性电子束 增长率     

损失锥-束流分布电子驱动的回旋激射不稳定性

在Chen等理论模型的基础上，对损失锥-束流分布电子激发的回旋激射不稳定性的主要特征 进行了深入研究，这种电子分布在太阳色球附近的磁重联过程中可能形成，它兼有束流和损 失锥的特性.结果表明，它不仅可以像束流分布和损失锥分布那样在适当的等离子体频率和 回旋频率的比值范围内激发X模和O模的基频和谐频不稳定性，兼有两种分布的激发特性，而 且具有更强的增长率.这一方面丰富了此类等离子体不稳定性的基本内容，而且预期在天体 射电发射机理的研究中也将得到广泛的应用. 关键词： 回旋激射不稳定性 弱相对论性 损失锥-束流分布电子 增长率     

一种同步回旋激射不稳定性对电磁波的直接放大

本文讨论了一种同步回旋激射不稳定性对电磁波的直接放大,它基于少量在速度空间具有空心分布的中等相对论性高能电子束与本底等离子体中本征电磁模的共振相互作用。主要关心的是的参数区域(ω_e为电子等离子体频率,Ω_e为电子回旋频率)。计算表明,若电子束的单能性很高,则不稳定性增长率比同样参数下由动力效应计算得出的增长率高若干个数量级,且最大增长率处在2ω_e附近。     

托卡马克等离子体逃逸放电中的驰豫振荡与电子回旋激射不稳定性

我们研究了托卡马克等离子体进制电子引起的电子回旋激射不稳定性发生的条件，发现由反常多普勒效应及切伦科夫效应确定的准稳态速度分布又会激发电子回旋激射不稳定性，且其对本底电子回旋辐射的放大频段低于回旋频率，这与ＨＬ－１实验观察一致。     

托卡马克等离子体逃逸放电中的驰豫振荡与电子回旋激射不…

我们研究了托马克等离子体逃逸电子引起的电子回旋激射不稳定性发生的条件，发现由反常多普勒效应及切伦科夫效应确定的准稳态速度分布又会激发电子回旋激射不稳定性，且其对本底电子回旋辐射的大频段于回旋频率，这与ＨＬ－１实验观察一致。     

自由电子激光的不稳振荡理论

自由电子激光最初是一种量子理论,后来F.A.Hopf等证明可用经典理论加以描述。本文将从解Vlasov-Maxwell方程的不稳振荡出发来讨论自由电子激光,所得结果不仅可用于相对论电子来通过横向周期磁场产生激光,而且也适用于光波或微波与相对论电子束相互作用产生激光。比较了各种方案,对电子束单色性要求是高的,接着又讨论了电子回旋激射器的不稳振荡,求得波纹回旋激射器问题的解.     

电子迴旋激射不稳定性

本文分析了下述情况下的电子迴旋波的激射不稳定性:当相对性的单能高能电子斜向注入具有背景等离子体的磁场区域内,并且在电子等离子体频率与电子迴旋频率可以比拟时,考虑了背景等离子体密度远大于单能的高能电子的密度,以及与前者相反的两种情况。当单能的高能电子具有弱相对论性效应时,在电子迴旋频率的基频和二次谐波附近,分别有ο模和χ模的不稳定性存在。文中计算了这两种模的增长率,并作了讨论。 关键词：     

提高等离子体密度抑制逃逸电子束不稳定性的实验研究

利用ECE电子回旋辐射和Ha线辐射等托卡马克物理诊断系统,研究了Slide-away放电过程中提高等离子体密度对非麦克斯维尔分布的逃逸电子所激发的逃逸电子束不稳定性影响作用.实验结果表明:在Slide-away放电模式下,提高等离子体密度能有效抑制逃逸电子束的不稳定性.     

提高等离子体密度抑制逃逸电子束不稳定性的实验研究

利用ECE电子回旋辐射和Ha线辐射等托卡马克物理诊断系统,研究了Slide-away放电过程中提高等离子体密度对非麦克斯维尔分布的逃逸电子所激发的逃逸电子束不稳定性影响作用。实验结果表明：在Slide-away放电模式下,提高等离子体密度能有效抑制逃逸电子束的不稳定性。     

电子束与等离子体相互作用中的反常效应

本文对强流相对论性电子束与靶等离子体相互作用的反常吸收效应进行了理论研究。从符拉索夫方程出发,导出了强流相对论性电子束双流不稳定性效应解,并进行了弱碰撞修正,得到了相应的等离子体波增长率,对不同情况下出现反常效应的条件及机制进行了研究和讨论。     

Effect of Opacity on Solar Coronal Soft X-Ray Oxygen VIII Spectral Line

To study the effect of opacity on the solar x-ray spectral line, using the method of escape factor, we analyze the effect of opacity on the solar oxygen VIII spectral line, and we estimate the effective emission thickness of the oxygen VIII emitting region in the solar atmosphere. Results show that the opacity has a greater effect on the solar oxygen VIII spectral line, and the effective emission thickness of the oxygen VIII ion is greater than that for some ions in the solar ultraviolet spectral line. This study has important reference significance in solar plasma diagnoses in the x-ray region.     

Calculated hydroxyl A2 sigma --> X2 pi (0, 0) band emission rate factors applicable to atmospheric spectroscopy

A calculation of the A2 sigma --> X2 pi (0, 0) band emission rate factors and line center absorption cross sections of OH applicable to its measurement using solar resonant fluorescence in the terrestrial atmosphere is presented in this paper. The most accurate available line parameters have been used. Special consideration has been given to the solar input flux because of its highly structured Fraunhofer spectrum. The calculation for the OH atmospheric emission rate factor in the solar resonant fluorescent case is described in detail with examples and intermediate results. Results of this calculation of OH emission rate factors for individual rotational lines are on average 30% lower than the values obtained in an earlier work.     

Numerical simulations of type-III solar radio bursts

The first numerical simulations are presented for type-III solar radio bursts in the inhomogeneous solar corona and interplanetary space, that include microscale quasilinear and nonlinear processes, intermediate-scale driven ambient density fluctuations, and large scale evolution of electron beams, Langmuir and ion sound waves, and fundamental and harmonic electromagnetic emission. Bidirectional coronal emission is asymmetric between the upward and downward directions, and harmonic emission dominates fundamental emission. In interplanetary space, fundamental and/or harmonic emission can be important. Langmuir and ion sound waves are bursty and the statistics of Langmuir wave energy agree well with the predictions of stochastic growth theory.     

Ionospheric Faraday amplitude modulation of radio-astronomical signals. I. Solar radio emission

Considerable time shifts of the amplitude maxima of solar radio emission were recorded during solar flare X38 of January 17, 2005 at the European VHF stations spaced by a distance of 100 to 1000 km. It is shown on the basis of the model of polarization interference of radio-astronomical signals [1] that this phenomenon can be stipulated by the amplitude modulation of solar radio emission caused by the rotation of the polarization plane in the ionosphere (Faraday effect). __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 50, No. 12, pp. 1029–1042, December 2007.     

Verification of a generalized Planck law for luminescence radiation from silicon solar cells

A generalization of Planck's radiation law based on the principle of detailed balance predicts the emission of luminescence radiation from absorption data for direct transitions in semiconductors. Its validity for indirect transitions is questionable due to the participation of phonons. We have tested the validity for the indirect transitions in Si by measuring absolute values of the emission intensity from Si solar cells under forward bias at room temperature and find good agreement with theoretical predictions based on existing absorption data. The generalized Planck law, thus verified for the indirect transitions in Si, allows to determine the performance of solar cell materials from measuring the absolute intensity of their emission of luminescence radiation when irradiated by the sun.     

Limits on light emission from silicon Invited Paper

Although silicon is an indirect semiconductor, light emission from silicon is governed by the same gener-alized Planck's radiation law as the emission from direct semiconductors. The emission intensity is given by the absorptance of the volume in which there is a difference of the quasi Fermi energies. A difference of the Fermi energies may rcsult from the absorption of external light (photoluminescence) or from the in-jection of electrons and holes via selective contacts (electroluminescence). The quantum efficiency may be larger than 0.5 for carrier densities below 1015 cm-3. At larger densities, non-radiative recombination, in particular Auger recombination dominates. At all carrier densities, the relation between emission intensity and difference of the quasi Fermi energies is maintained. Since this difference is equal to the voltage of a properly designed solar cell, luminescence is the key indicator of material quality for solar cells.     

“Hot” bands of CO and the effect of vibration-rotation interaction on the solar CO spectrum

For the first overtone bands of CO, theoretical Herman-Wallis factors and experimental values show some inconsistencies for high excitation transitions. To resolve this problem, the relative band intensities, as well as the relative line intensities, are examined with CO lines in the solar infrared spectrum. The relative rotationless dipole-moment matrix elements and the Herman-Wallis factors for 2-0, 3-1, 4-2, 5-3 and 6-4 bands obtained from the solar CO spectrum are reasonably consistent with the theoretical predictions based on the dipole-moment function but disagree with results obtained in high-temperature emission measurements. It is shown that a reinterpretation of the high-temperature emission measurements is possible; the resulting Herman-Wallis factors become compatible with theoretical predictions as well as with the solar analysis.     

Spectral peculiarities of high energy X-ray radiation,gamma radiation,and Submillimeter radio emission in the impulsive phase of a solar flare

We analyze experimental data on the temporal behavior of fluxes and energy spectra of hard solar X-ray and gamma radiation in the energy range of 0.015 to 300 MeV, obtained onboard the CORONAS-F satellite during a solar flare on August 25, 2001. These data are compared with measurements of the radio emission fluxes over the wide frequency range of 1–405 GHz. For our analysis, we use data obtained onboard the YOHKOH, TRACE and GOES satellites, along with ground-based observations of this solar event using the Solar Submillimeter Telescope (SST; Argentina). For the first time, we find nearly simultaneous changes in the energy spectra of gamma radiation over the range 10–150 MeV and the frequency spectrum of radio emission at the beginning and during a impulsive phase of this event (whose duration did not exceed three minutes).     

The Results of Studying Nonstationary Processes on the Sun by Radioastronomical Methods

This paper presents the results of studies of solar phenomena performed at the Radiophysical Research Institute (NIRFI) in the last years and based on the data of measuring the solar microwave radiation. We obtained new results concerning fragmentation of the regions of initial energy release during solar flares, their spatial and temporal dynamics, the physical conditions in flaring loops, the dynamics of energetic particles accelerated during flares, and the characteristics of sporadic radio emission during the formation and propagation of coronal mass ejections in the lower layers of the solar atmosphere.     

太阳过渡区紫外光谱的观测与诊断

太阳过渡区是太阳色球层顶到日冕底部的大气薄层。厚度仅几百千米,但其间太阳等离子体参数变化剧烈。过渡区的辐射多为光学薄的远紫外、极紫外发射谱线和背景连续谱线。由于地球大气的吸收,过渡区紫外光谱需通过天基观测才能实现。近几十年来,星载仪器的成功发射为太阳过渡区的研究打开了新纪元。工作回顾了太阳过渡区紫外光谱的观测历史和各类星载仪器,特别介绍了近十几年几种重要的光谱仪器。详细阐述了过渡区紫外光谱的发生率、电子密度和电子温度的诊断原理。讨论了过渡区紫外谱线的形状,并以SOHO/SUMER光谱仪为例介绍了表征谱线的几种重要参量及其物理意义。