Compression in Magnetized Shocks

Compression across a magnetic shock as a function of the fast magnetosonic Mach number for an ideal monoatomic gas when the incident magnetic field lies entirely in the plane of the shock (theta = 90 degrees). The f = 0 line corresponds to the nonmagnetic case. When the shock velocity greatly exceeds both the Alven speed V_A and the sound speed C_S, the compression approaches 4, while C --> 1 for the weakest shocks.