可变比冲磁等离子体火箭原理与研究进展

介绍了VASIMR的基本组成(螺旋波等离子体源、离子回旋共振加热系统I-CRH、磁喷嘴)及工作原理。可变比冲磁等离子体火箭(VASIMR)是一种基于可控核聚变思想发展的先进高功率电推进方式,具有高比冲、比冲可变等特点。通过分析系统的效率及关键技术,指出VASIMR研制最关键的问题是研制高性能的螺旋波等离子体源和提高ICRH的效率等,最后评估了VASIMR在空间任务中的优势。     

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.