INFLUENCE OF HIGHER ORDER TOROIDICITY ON COUPLING OF TEARING MODES

he general dispersion relation for toroidally coupled tearing mode including pressure and other O(ε²) order corrections is naturally derived based on the structure of ideal magnetohydro-dynamic solutions in the outer region. It is found that the inclusion of the O(ε²) order terms in the diagonal element of E-matrix does not change physical properties of the toroidally coupled tearlng mode and only make negligible contribution to the magnitude of growth rate.     

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     

磁驱动滑移弧的放电特性研究

讨论了被外磁场驱动的滑移弧。磁驱动滑移弧的放电频率随磁感应强度增大而增大,测得的放电频率约在46～517Hz之间;当外加磁感应强度为0.4829T时,用光电倍增管测得滑移弧运动的平均速度为26.4m·s-1;从磁驱动滑移弧的放电电压曲线可以看出,电弧运行在电极平行段时,电压增加缓慢,当电弧运动到电极顶部时,电压上升较快,从1778V迅速增加到约4000V。     

Propagation of Fast Magnetoacoustic Waves in Stratified Solar Atmosphere

The characteristics of magnetohydrodynamic fast wave propagation in the solar stratified atmosphere are studied by the ray tracing method. The propagation behaviour of the wavefronts is described in detail. A magnetic field incorporating the characteristics field spreading expected in flux tubes is used, which represents the main feature of an active region. Partly ionization is considered beside the stratified solar atmosphere consisting chromosphere, transition region and corona. The study may explain the characteristics in observations of Moreton and extraultraviolet image telescope （EIT） waves. The wavefront incurred by the disturbance initialized at the base of the transition region propagates fast initially due to strong magnetic field, and it slows down when arriving beyond the region of flux-tube. Meanwhile, the wave propagates in the corona with a more consistent speed, as seen in the observation of EIT waves. The speeds and propagated characteristics in chromosphere and corona of the wavefronts are in agreement with those observed in H~ Moreton and EIT waves, respectively.     

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讨论了在相距25.0mm长度40.0mm的平行电极间的由强度可达6040Gs的外磁场驱动的滑移弧功率变化过程,分析了滑移弧等离子体所处的状态。当电弧运行在电极平行段时,电弧功率在0.65kW附近剧烈振荡;当电弧接近平行电极顶端时,电弧功率由约0.65kW迅速增加到约2.0kW。在一个放电周期内,电弧功率基本上是从小到大持续增加的,由弧电源提供能量来维持滑移弧等离子体的平衡状态。根据Ozlem Mutaf-Yardimici等人的理论,此时滑移弧等离子体仍处于平衡态。