Ion and electron heating in the earth's bow shock region

Ion and electron heating in the earth's bow shock region is studied in terms of the modified two stream instability by treating the electron's response to be electromagnetic and that of ions to be electrostatic. The modified two stream flute mode, driven unstable by the density and temperature gradients, can heat the ions to about 50 times their upstream temperature. However, the electrons are heated mainly by the non-flute mode and their temperature can be increased by a factor of 1·5 or more. Consequently the ions will be hotter than the electrons downstream of the shock, as observed by satellites.