Geoscience Reference
In-Depth Information
Fig. 1. (
Right; from top to bottom
) Final altitude, energy, minimum adiabaticity param-
eter
κ
, and time of flight of solar wind H
+
as a function of initial longitude and latitude
at the magnetopause. Test H
+
are traced until they reach the model boundary (i.e., the
magnetopause or a radial distance of 6
R
M
) or precipitate onto Mercury's surface. (
left
)
Examples of (
top
) resonant and (
bottom
) non-resonant particles (adapted from Ref. 6).
In the right panels of Fig. 1, a prominent structuring of the precipi-
tating ion energy and time of flight can also be seen, that directly follows
from non-adiabatic transport in the mid-tail. Indeed, in their analysis of
non-linear particle dynamics in a field reversal, Chen and Palmadesso
7
put
forward that, for some values (smaller than 1) of the
κ
parameter, particles
preferentially execute Speiser-type orbits whereas, for other
κ
values, most
of the particles experience prominent magnetic moment scattering and are
temporarily trapped inside the current sheet. This feature was interpreted
as the result of resonance between the fast meandering motion about the
mid-plane and the slow gyromotion about the normal field component. To
characterize these resonances, Chen and Palmadesso
7
derived the follow-
ing empirical relationship:
κ
n
≈
0
.
8
/
(
n
+0
.
6), where
n
is an integer
≥
1.
These resonances coincide with the quasi-adiabatic regime put forward by
