Ion-acoustic waves in the solar wind. Progress report

Technical Report · Tue Mar 01 04:00:00 EST 1977

OSTI ID:7100271

Gurnett, D A; Frank, L A

Plasma wave measurements on the Helios 1 and 2 spacecraft have revealed the occurrence of electric field turbulence in the solar wind at frequencies between the electron and ion plasma frequencies. Wavelength measurements with the IMP 6 spacecraft now provide strong evidence that these waves are short wavelength ion-acoustic waves which are Doppler shifted upward in frequency by the motion of the solar wind. Comparison of the Helios results with measurements from the earth-orbiting IMP 6 and 8 spacecraft shows that the ion-acoustic wave turbulence detected in interplanetary space has characteristics essentially identical to bursts of electrostatic turbulence generated by protons streaming into the solar wind from the earth's bow shock. In a few cases enhanced ion-acoustic wave intensities have been observed in direct association with abrupt increases in the anisotropy of the solar wind electron distribution. This relationship strongly suggests that the ion-acoustic waves detected by Helios far from the earth are produced by an electron heat flux instability, as suggested by Forslund. Possible related mechanisms which could explain the generation of ion-acoustic waves by protons streaming into the solar wind from the earth's bow shock are also considered.

• Research Organization: Iowa Univ., Iowa City (USA). Dept. of Physics and Astronomy
• OSTI ID: 7100271
• Report Number(s): AD-A-039092; U-OF-IOWA-77-10
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ELECTRIC FIELDS
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
ION ACOUSTIC WAVES
ION WAVES
KINETICS
LEPTONS
PLASMA WAVES
SOLAR ACTIVITY
SOLAR WIND
TURBULENCE