Electrostatic bursts generated by electrons trapped in whistler mode chorus wave fields
Recent studies of wideband plasma wave data from the ISEE-1 and ISEE-2 spacecraft have revealed that whistler mode chorus emissions in the Earth's outer magnetosphere are often accompanied by high frequency bursts of electrostatic waves with a frequency below the electron plasma frequency. Investigations have shown that in some cases the electrostatic waves are found to be modulated at the chorus frequency. Further studies indicate through use of LEPEDEA data on ISEE-1 that there bursts are being produced by a ''beam'' of electrons trapped in Landau (longitudinal) resonance in effective potential wells of chorus wave and thus moving at the chorus phase velocity. There seems to be a lower threshold in chorus intensity, below which the electrostatic bursts do not appear. The high frequency electrostatic waves appear to be caused by a type of two-stream instability called the resistive-medium instability, produced by these trapped electrons. The reduction in the electrostatic burst frequency to below the plasma frequency is a characteristic of the resistive-medium instability. The instability is applicable only in the regime where (V/sub 0/)/(V/sub T/) is on the order of 1, where V/sub 0/ is the velocity of the beam and V/sub T/ is the averaged thermal velocity of the plasma electons. The derivation assumes cold ions but warm electrons in the plasma. The instability requires Landau damping to operate, and thus the beam velocity must be in the steep slope region of the plasma electron distribution function rather than the high velocity tail region. In examined cases from LEPEDEA data the electron thermal energies are on the order of a few hunder eV.
- Research Organization:
- Iowa Univ., Iowa City (USA)
- OSTI ID:
- 6913695
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
MAGNETOSPHERE
PLASMA WAVES
LANDAU DAMPING
LANGMUIR FREQUENCY
TRAPPED ELECTRONS
TWO-STREAM INSTABILITY
VELOCITY
WHISTLERS
DAMPING
EARTH ATMOSPHERE
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
INSTABILITY
LEPTONS
NOISE
PLASMA INSTABILITY
PLASMA MICROINSTABILITIES
RADIATIONS
RADIO NOISE
RADIOWAVE RADIATION
640203* - Atmospheric Physics- Magnetospheric Phenomena- (-1987)