  We consider a fast magnetosonic multifluid shock as a representation of the
solar-wind termination shock. We assume the action of the transition happens in
a three-step process: In the first step, the upstream supersonic solar-wind
plasma is subject to a strong electric field that flashes up on a small
distance scale $\Delta z\simeq U_1/ \Omega _{\mathrm e}$ (first part of the
transition layer), where $\Omega_{\mathrm e}$ is the electron gyro-frequency
and $U_1$ is the upstream speed. This electric field both decelerates the
supersonic ion flow and accelerates the electrons up to high velocities. In
this part of the transition region, the electric forces connected with the
deceleration of the ion flow strongly dominate over the Lorentz forces. We,
therefore, call this part the demagnetization region. In the second phase,
Lorentz forces due to convected magnetic fields compete with the electric
field, and the highly anisotropic and energetic electron distribution function
is converted into a shell distribution with energetic shell electrons storing
about 3/4 of the upstream ion kinetic energy. In the third phase, the plasma
particles thermalize due to the relaxation of free energy by plasma
instabilities. The first part of the transition region opens up a new
thermodynamic degree of freedom never before taken into account for the
electrons, since the electrons are usually considered to be enslaved to follow
the behavior of the protons in all velocity moments like density, bulk
velocity, and temperature. We show that electrons may be the downstream plasma
fluid that dominates the downstream plasma pressure.
