What happens at the X-point ?
The plasma current that is induced at the X-point by Faraday's law as
reconnection proceeds is carried out with moving electrons. Here, we have to
recall that electrical resistivity was brought into the MHD theory to dissipate
the X-point current which blocks magnetic reconnection by its repulsive
forces
against a newly incoming plasma into that region. Hence, no necessity of such
an artificial term if other mechanism of reducing the X-point current exists,
and it really does, as it was shown by my macro-particle simulations.
History Repeats Itself？
For the sake of impartiality, we refer to a pre-existing theory by Dr.Speicer.
In late 1960s he thought of electrons as the agent to carry out the X-point
current, which was termed electron inertia resistivity. However, his theory relied
on several assumptions, and because of criticism by H.Alfven and uprising
popularity of anomalous resistivity - direct conversion of magnetic fusion theory,
Speicer's theory was forgotten. Many researchers studied plasma instabilities
and anomalous resistivity in 1970s. Ironically, I was engaging in the
study of
the LHD (lower-hybrid drift) instability as a possible origin of dissipation
in my
PhD thesis work. Ten years later, I came back to the subject, and proved the
origin of the dissipation for magnetic reconnection using my macro-particle
simulation code.
References：
First proof of collisionless magnetic reconnection
Phys.Plasmas 2, 2920 (1995).
Roles of protons and electrons in magnetic reconnection
Phys.Plasmas, 3, 4010 (1996).
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