Magnetic Fluctuation Power Near Proton Temperature Anisotropy Instability Thresholds in the Solar Wind

被引：417

作者：

Bale, S. D. ^{[1
,2
]}

Kasper, J. C. ^{[3
]}

Howes, G. G. ^{[4
]}

Quataert, E. ^{[1
,5
]}

Salem, C. ^{[2
]}

Sundkvist, D. ^{[2
]}

机构：

[1] Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA

[2] Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA

[3] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA

[4] Univ Iowa, Dept Phys & Astron, Iowa City, IA 52242 USA

[5] Univ Calif Berkeley, Dept Astron, Berkeley, CA 94720 USA

来源：

PHYSICAL REVIEW LETTERS | 2009年 / 103卷 / 21期

关键词：

PLASMA; FIELD; MAGNETOSHEATH; CONSTRAINT; TURBULENCE; WAVES; BETA;

D O I：

10.1103/PhysRevLett.103.211101

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

The proton temperature anisotropy in the solar wind is known to be constrained by the theoretical thresholds for pressure-anisotropy-driven instabilities. Here, we use approximately 1x10(6) independent measurements of gyroscale magnetic fluctuations in the solar wind to show for the first time that these fluctuations are enhanced along the temperature anisotropy thresholds of the mirror, proton oblique firehose, and ion cyclotron instabilities. In addition, the measured magnetic compressibility is enhanced at high plasma beta (beta(vertical bar)greater than or similar to 1) along the mirror instability threshold but small elsewhere, consistent with expectations of the mirror mode. We also show that the short wavelength magnetic fluctuation power is a strong function of collisionality, which relaxes the temperature anisotropy away from the instability conditions and reduces correspondingly the fluctuation power.

引用

页数：4

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