  Efficiency of electron heating through microinstabilities generated in the
transition region of a quasi-perpendicular shock for wide ange of Mach numbers
is investigated by utilizing PIC (Particle-In-Cell) simulation and model
analyses. In the model analyses saturation levels of effective electron
temperature as a result of microinstabilities are estimated from an extended
quasilinear (trapping) analysis for relatively low (high) Mach number shocks.
Here, MTSI (modified two-stream instability) is assumed to become dominant in
low Mach number regime, while BI (Buneman instability) to become dominant in
high Mach number regime, respectively. It is revealed that Mach number
dependence of the effective electron temperature in the MTSI dominant case is
essentially different from that in the BI dominant case. The effective electron
temperature through the MTSI does not depend much on the Mach number, although
that through the BI increases with the Mach number as in the past studies. The
results are confirmed to be consistent with the PIC simulations both in
qualitative and quantitative levels. The model analyses predict that a critical
Mach number above which steep rise of electron heating rate occurs may arise at
the Mach number of a few tens.
