Is the Near-Earth Current Sheet Prior to Reconnection Unstable to Tearing Mode

• Published in: Chinese physics letters 2010-02, Vol.27 (2), p.330-333
• Main Author: 魏新华 曹晋滨 周国成 符慧山
• Format: Article
• Language: English
• Subjects: 不稳定性; 功率谱密度; 数值结果; 电流片; 稳定性理论; 等离子体片; 触发条件; 重联
• ISSN: 0256-307X; 1741-3540
• DOI: 10.1088/0256-307X/27/2/029401

The tearing mode instability plays a key role in the triggering process of reconnection. The triggering collisionless tearing mode instability has been theoretically and numerically analyzed by many researchers. However, due to the difficulty in obtaining the observational wave number, it is still unknown whether the tearing mode instability can be excited in an actual plasma sheet prior to reconnection onset. Using the data from four Cluster satellites prior to a magnetospheric reconnection event on 13 September 2002, we utilized the wave telescope technique to obtain the wave number which corresponds to the peak of power spectral density. The wavelength is about 18RE and is consistent with previous theoretic and numerical results. After substituting the wave vector and other necessary parameters of the observed current sheet into the triggering condition of tearing mode instability, we find that the near-Earth current sheet prior to reconnection is unstable to tearing mode.