Observations of Langmuir ponderomotive effects using the Solar TErrestrial RElations Observatory spacecraft as a density probe
Abstract
Langmuir ponderomotive effects are nonlinear effects that enable to couple the electron and ion dynamics in space plasmas. The main difficulty to provide observational evidence of such nonlinear coupling is to simultaneously observe both fluctuations of plasma density and electric field. We have thus developed a new method to measure and to calibrate in situ small scale density fluctuations. Density fluctuations in the solar wind are measured using the observed quasistatic fluctuations of the STEREO spacecraft floating potential in the frequency range, where the spacecraft floating potential is in quasistatic equilibrium between photoionization and electron attachment, whereas the potential of the antenna, of much longer equilibrium time scale, is blind to the density fluctuations. Density fluctuations and Langmuir waves are thus directly and simultaneously measured using a dataset of more than three years of STEREO/WAVES measurements. We present here the first observational evidence for ponderomotive effects in the solar wind that nonlinearly couple density fluctuations to high energy Langmuir waves ((ɛ0E2)/(nkBT)>10-4).
- Publication:
-
Physics of Plasmas
- Pub Date:
- August 2011
- DOI:
- 10.1063/1.3622667
- Bibcode:
- 2011PhPl...18h2308H
- Keywords:
-
- antennas in plasma;
- astrophysical plasma;
- Langmuir probes;
- photoionisation;
- plasma density;
- plasma fluctuations;
- plasma Langmuir waves;
- plasma nonlinear waves;
- solar wind;
- 52.35.Mw;
- 52.40.Fd;
- 52.70.Ds;
- 52.35.Fp;
- 52.25.Jm;
- 52.25.Gj;
- Nonlinear phenomena: waves wave propagation and other interactions;
- Plasma interactions with antennas;
- plasma-filled waveguides;
- Electric and magnetic measurements;
- Electrostatic waves and oscillations;
- Ionization of plasmas;
- Fluctuation and chaos phenomena