Geoscience Reference
In-Depth Information
contribute to the understanding of the plasma supply and loss mechanisms
associated with ion waves.
2.2.4.
Search for transient radiation belts in the hectometric
radio range
No stable radiation belts are expected around Mercury. But, synchrotron
transients could be produced from transient radiation belts with MeV elec-
trons. Synchrotron radiation might peak near a few MHz.
2.3.
Energy transfer and scale coupling
2.3.1.
Nature of substorms
Because of the much smaller magnetosphere, the time scale of substorms
at Mercury will be shorter. Thus, a better understanding of the loading-
unloading process will be gained by comparison with substorms at Earth.
Electric fields associated with fast reconfigurations of the magnetosphere
will accelerate charged particles.
2.3.2.
Reconnection
Reconnection of the magnetosphere plays important roles in energy trans-
fer from the solar wind to the magnetosphere. The process of reconnection
involves coupling of microscale and mesoscale phenomena such as various
types of beam or current driven instabilities resulting in heating and accel-
eration of electrons and ions, which excite various types of plasma waves
through nonlinear wave-particle interaction, dissipating the energy of the
accelerated particles.
2.3.3.
Identification of auroral processes
Current closure may require acceleration of particles along the magnetic
field. Thus, a large electric field enhancement similar to the auroral accel-
eration region may be expected. In the case the auroral radio emissions
exist, their source regions are expected to be very close to the planet polar
surface. Therefore, we can estimate their frequency range is around 20 kHz.
The scaling law predicts an auroral radio power of 10
6
-
7
W.
2.4.
Wave-particle interactions
2.4.1.
Nonlinear kinetic processes
In the dayside, the solar wind plasma sometimes interacts with the pho-
toelectron cloud above the Mercury surface directly, and leads to current
