Electromagnetic ion cyclotron resonance heating in the VASIMR

Plasma physics has found an increasing range of practical industrial applications, including the development of electric spacecraft propulsion systems. One of these systems, the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) engine, both applies several important physical processes occurring in the magnetosphere. These processes include the mechanisms involved in the ion acceleration and heating that occur in the Birkeland currents of an auroral arc system. Auroral current region processes that are simulated in VASIMR include lower hybrid heating, parallel electric field acceleration and ion cyclotron acceleration. This paper will focus on using a physics demonstration model VASIMR to study ion cyclotron resonance heating (ICRH). The major purpose is to provide a VASIMR status report to the COSPAR community. The VASIMR uses a helicon antenna with up to 20 kW of power to generate plasma. This plasma is energized by an RF booster stage that uses left hand polarized slow mode waves launched from the high field side of the ion cyclotron resonance. The present setup for the booster uses 2–4 MHz waves with up to 20 kW of power. This process is similar to the ion cyclotron heating in tokamaks, but in the VASIMR the ions only pass through the resonance region once. The rapid absorption of ion cyclotron waves has been predicted in recent theoretical studies. These theoretical predictions have been supported with several independent measurements in this paper. The ICRH produced a substantial increase in ion velocity. Pitch angle distribution studies show that this increase takes place in the resonance region where the ion cyclotron frequency is equal to the frequency on the injected RF waves. Downstream of the resonance region the perpendicular velocity boost should be converted to axial flow velocity through the conservation of the first adiabatic invariant as the magnetic field decreases in the exhaust region of the VASIMR. In deuterium plasma, 80% efficient absorption of 20 kW of ICRH input power has been achieved. No evidence for power limiting instabilities in the exhaust beam has been observed.     

Preliminary results of fair-weather atmospheric electric field in the proximity of Main Boundary Thrust,Northern Pakistan

The atmospheric electric Potential Gradient (PG) variation of fair-weather days at Muzaffarabad (MZF, Northern Pakistan) station is presented for the period of January 2015–October 2017. The present investigations focus on the diurnal variation of atmospheric PG on the seasonal and annual time scale. The fair-weather seasonal and annual average PG variation has revealed two peaks, i.e. a primary maximum peak and a secondary maximum peak. The average maximum PG value found is ～410?Vm^?1. The results are then compared with the well-known standard oceanic Carnegie curve. The diurnal curve of PG is found to deviate from the Carnegie curve. The seasonal PG variation at MZF shows lower values during the summer (monsoon) and autumn (post-monsoon) as compared to the winter and spring (pre-monsoon) which could be due to local aerosol concentration. Global comparison of PG (%) values of the annual mean at different longitude, with MZF observatory, shows local morning and evening peaks depicting local sunrise and sunset effects on the PG. The overall outcomes will certainly contribute to further investigate the Global Electric Circuit (GEC).     

战术导弹发动机无线电干扰滤波器可靠性验证试验

战术导弹发动机无线电子干扰滤波器是确保导弹发动机战勤安全的一个重要电子产品。为了评价它的可靠性，需对其进行可靠性验证试验。据此，结合一种导弹发动机无线电干扰滤波器的可靠性验证试验，讨论了其可靠性验证试验的数学模型，试验方案设计和试验方面的有关问题。     

电动车跷跷板系统的设计与实现

系统采用一块单片机AT89S52作为跷跷板检测和电动车控制的核心,实现了电动车在不同状态下的往返行驶、起始和停止位置的判断,以及行驶时间的显示以及跷跷板平衡点的寻找等功能。     

Solar filament eruptions and their physical role in triggering coronal mass ejections

Solar filament eruptions play a crucial role in triggering coronal mass ejections (CMEs). More than 80% of eruptions lead to a CME. This correlation has been studied extensively during the past solar cycles and the last long solar minimum. The statistics made on events occurring during the rising phase of the new solar cycle 24 is in agreement with this finding. Both filaments and CMEs have been related to twisted magnetic fields. Therefore, nearly all the MHD CME models include a twisted flux tube, called a flux rope. Either the flux rope is present long before the eruption, or it is built up by reconnection of a sheared arcade from the beginning of the eruption.     

静电效应及其防护

静电放电是两个具有不同电位的物体,由于直接接触或静电场感应而引起的两物体间电荷的转移,静电放电产生宽带干扰。本文分析了静电干扰的机理,并介绍了飞机及机上的燃油、电爆装置、信息技术设备的静电防护措施和电子产品静电放电敏感度测试方法。     

电火花加工放电位置检测的电测量法

介绍了应用于电火花加工放电点位置检测中的信号检测和电磁信号检测法 ,同时指出它们各自的特点。在实际应用中 ,应根据不同的加工要求来选取不同的检测方法 ,实现电火花加工的最优控制 ,从而达到最好的加工效果。     

场致发射电推力器发射尖端理论模型及机理

为了研究铟场致发射电推力器的发射过程及机理,对椭球顶喷流柱模型离子发射区流柱的形状及尺寸进行了数学描述并通过数值计算加以验证,结果表明,椭球顶喷流柱模型具有合理性,从Taylor理论出发,结合电磁场理论、流体力学理论以及场致发射理论,讨论了离子形成的机理,发现场蒸发是离子产生的重要原因。     

一种热电势的简易表达法

当具有不同温度分布的多种导体连接在一个环路中时,按照帕尔贴电势和汤姆逊电势分析环路中的总的热电势是困难的。选择一些导体作为标准电极,就能把总的热电势分成一系列单一导体的独立热电势,用这个方法,分析工作将变得十分简单。     

航天电连接器的选用

为确保航天系统工程广泛使用的重要配套接口元件－－电连接器的使用可靠性，详细介绍了其选用的一般要求和特殊要求，各项技术参数（电参数、安全参数、环境参数等）的选择方法，最后讨论了电连接器在使用前和使用过程中的注意事项。